LSST: mining the sky in 4D

The Large Synoptic Survey Telescope (LSST) is going to be a unique astronomical instrument.
“Unlike a lot of other telescopes around the world, LSST is actually aptly named,” joked Dr. David Reiss of the University of Washington at a recent gathering of Astronomy on Tap Seattle at Peddler Brewing Company in Ballard. Reiss and Dr. John Parejko, two UW astronomers involved in the project, gave an overview of the telescope, which is under construction in Chile.

John Parejko (left) and David Reiss, research scientists at the
University of Washington, discussed the Large Synoptic Survey
Telescope at an Astronomy on Tap Seattle event October 28 at
Peddler Brewing Company in Ballard. Photo: Greg Scheiderer.

As for the name, Parejko noted the scope will be truly large. It will have an 8.4-meter mirror, a 3.2-gigapixel camera, and will take an image of the night sky every 30 seconds.

“We’re going to generate 15 terabytes of data every single night,” Parejko noted. “That means by the end of the survey we’ll have 30 trillion database entries, and over half an exabyte of data and images being catalogued.”

“That’s a lot of data even for those of you who work at Amazon,” he quipped.

Synoptic is the word even the scientists say they have to look up every time. Essentially it means that the instrument will look at everything as a whole and provide a synopsis.

“Unlike a lot of other telescopes, the LSST has been designed to serve thousands of astronomers with interests ranging from supernovae or exploding stars, to planets and asteroids, to the universe as a whole,” Reiss explained.

It’s a survey because LSST will not look at just one object.

“Not only is it covering all kids of different science, it’s actually covering the whole sky,” Parejko said. They hope to start observing in 2022, and the 10-year survey will photograph the entire sky every three nights. They expect to discover 37 billion stars and galaxies.

Lastly, it’s a telescope, but it’s much more.

“The main thing that LSST is going to produce is lots and lots of data,” Reiss said, “images and catalogs and databases of all of the objects in the sky that are going to be shared with everybody in real time.” With new information coming in constantly, they’ll be effectively creating a 10-year, multi-color, ultra high-resolution movie of the night sky.

The building

Parejko described the facility, which is being built on the Cerro Pachón ridge at 8,700 feet elevation, not far from town of La Serena in the mountain desert of Chile. It’s a good site for an observatory, with high elevation and low humidity. The building has been designed with a lab for working on the mirror and other parts of the telescope so that they don’t have to send things off the mountain for repairs.

“That means we minimize our down time; we can spend as much time as possible taking data,” Parejko said. You can watch progress of the construction on the LSST webcam.

An artists’ concept of the Large Synoptic Survey Telescope.
Image: LSST.

The telescope itself will be short, squat, and compact, with the secondary mirror and camera located out at the end. They’re building it short to reduce wobble when it moves—another measure for minimizing down time. They were able to keep it short by using a different shape on the outside of the primary mirror than on the inside. Light will come into the scope, reflect off the outside of the primary to the secondary mirror, back down to the inside of the primary, which will beam it up to the camera.

“That’s how we can keep the telescope so short and compact, by folding the light like that,” Parejko explained.

The camera, about the size of a Smart Car, will have three lenses and space for five filters. The detector will feature 21 “rafts” each with nine CCDs. If one raft breaks, they’ll just pull it out, plug in another, and keep imaging.

The building will also include a major computer lab. That’s still under design.

LSST software

Reiss explained that, with so much data being collected, computing will be important. Essentially, they’re building, “sort of a Google index of the entire night sky over the course of ten years.” To do that, they’re creating a high-speed network to connect the telescope in Chile to a supercomputing center in Illinois. There, they’ll look for things that move or blow up, and expect to spot some 10 million events every night. Information about these discoveries will go out in nightly alerts to interested users.

“We’re basically providing the equivalent of astronomical Twitter, Google, and Amazon Web Services to the community,” Reiss said.

“We’re going to be sending out nearly 600 gigabytes worth of simply just these alerts every night,” he added. “If one of you were going to subscribe to these you’re going to max out your Comcast monthly allocation in one night.”

Researchers will be able to upload their software or algorithms into the LSST computing cluster and do calculations in the cloud, rather than having to download all of that data. Many institutions will receive the alerts and write algorithms that will help users pick and choose data. There will likely be smartphone apps that will allow users to, say, track their favorite asteroid, and people will be able to use the data to learn about the universe or do citizen science. Reiss noted that, by keeping a constant eye on the sky, we will be able to spot lots of the sorts of things that we only find today through the luck of looking in the right place at the right time.

LSST goals

The main science goals of the LSST are to learn about dark matter and dark energy, catalog the solar system, watch how things change, and learn about the structure and formation of the Milky Way.

The LSST team includes 39 institutional members, among them 21 colleges and universities. The UW is a founding member. The project employs 200 astronomers and engineers from 19 different countries. The total cost of getting LSST up and running by 2022 will be about $400 million. That sounds like a lot of money, but Reiss and Parejko pointed out, given the season, that it’s about what Americans spend on Halloween costumes for their pets in a typical year. Funding for the project has come from the National Science Foundation, the U.S. Department of Energy, and through fundraising by the nonprofit LSST Corporation.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. The events are free, but you can help them cover the costs of creating them by donating online to the Friends of Astronomy Fund at the UW.

Learning about LIGO at Astronomy on Tap

The most recent gathering of Astronomy on Tap Seattle brought to town two scientists working in one of the most groundbreaking areas of astronomy: detection of gravitational waves.

Nature was kind to us

Jeff Kissel, a control systems engineer at the LIGO Hanford Observatory, talked about how exciting it was when they switched on advanced LIGO back in September 2015.

“Boom! Right out of the gate we saw this whopper of an event,” Kissel said, detecting gravitational waves from the merger of a pair of stellar-mass black holes. “Nature was very kind to us.”
What they spotted at Hanford and at LIGO in Livingston, Louisiana was a match.

“Inside our data, which is almost always noise, we saw this very characteristic wave form that was predicted by general relativity,” Kissel recalled. They found gravitational waves from a couple of other black-hole mergers in the following months.

“This is the beginning of gravitational wave astronomy,” Kissel said.

Gravitational waves oscillate through spacetime in a way
demonstrated by this animation. Credit: ESA–C.Carreau

Kissel pointed out that LIGO only detects a small part of the gravitational wave spectrum. As with light, gravitational waves can come in a wide range of wavelengths with periods ranging from milliseconds to billions of years. Longer-length waves might come from the mergers of galactic nuclei, or even from quantum fluctuations from the early universe.

“There’s a whole zoo of things to find out there,” Kissel said. He anticipates more ground-based observatories as well as some space LIGOs that could have detector arms millions of kilometers long.

How LIGO works

LIGO sounds awfully complicated, but, broken down, the idea is pretty simple. Jenne Driggers
is a Caltech postdoctoral scholar stationed at the LIGO Hanford Observatory, where her gig is improving the sensitivity of the interferometers. Driggers explained that, essentially, they shoot a laser beam into a splitter that sends beams down two equal arms four kilometers long. The beams reflect from mirrors and return to be put back together.

A simplified look at how LIGO works. A laser beam is split and sent down two equal
arms four kilometers long, then reflected back by mirrors. When they return to be
recombined, they will usually cancel each other out and no light will get to the detector.
But if a gravitational wave distorts the system, the light will be spotted by the detector.Credit: T. Pyle, Caltech/MIT/LIGO Lab

“When they recombine they can be exactly out of phase, and then there’s no laser light (at the detector),” Driggers said. “They cancel each other out totally. Or the lengths will change and these two electromagnetic waves can add up, and so we do get some light.”

When that happens it means that a gravitational wave has distorted the LIGO arms ever so slightly. They measure the light received at the detector to learn more about the wave.

In practice it’s a lot more complicated. It all happens in a total vacuum to avoid any distortion from air. The mirrors are suspended from a system of four pendulums, which helps to eliminate vibration. The mirrors are highly reflective pieces that each weigh around 100 pounds and cost half a million dollars. The laser is about the best there is.

“The laser wavelength itself is our ruler that we’re using to measure the distance between those two mirrors,” Driggers said, “and we need to be able to measure that distance to 10^-19 meters.”

“This is one of the highest-power, frequency stable, power-stable lasers on the planet,” she added.
Driggers invited people to tour LIGO Hanford. Public tours are held twice each month, and groups of 15 or more can arrange for a private tour.

Up next: LSST

Astronomy on Tap Seattle is presented and organized by astronomy graduates students at the University of Washington. Their next event is planned for Friday, October 28 at Peddler Brewing Company in Ballard and will feature UW scientists Dr. John Parejko and Dr. David Reiss, who are working on the Large Synoptic Survey Telescope project. The events are free. Enjoy beer and astronomy!

Space oddities at Astronomy on Tap Seattle

Things got a little strange at the most recent gathering of Astronomy on Tap Seattle, and not just because we were all drinking beer at Hilliard’s Beer Taproom in Ballard and enjoying eats from the Cave Man Food Truck parked outside. The event, organized by astronomy graduate students at the University of Washington, took on space oddities like Hanny’s Voorwerp and Thorne-Żytkow Objects.

Seattle Astronomy gets all sentimental about Hanny’s Voorwerp because it has a cool name and it was a subject of our third post ever when we started this effort in January 2011. The Voorwerp was noticed by Hanny van Arkle, a Dutch schoolteacher who was categorizing galaxies in Sloan Digital Sky Survey images as part of the Galaxy Zoo project. The object (voorwerp is Dutch for thing or object) appeared as a blue blob near the galaxy IC 2497.

What’s a voorwerp?

Ruan

During his talk titled, “Citizen Discovers Strange Black Hole Echoes: The Science Behind Hanny’s Voorwerp,” UW graduate student John Ruan said there were four ideas about what it was. All of them were wrong.

Imaging artifact. It could have been just a blip on the camera, Ruan said, but other observers were able to spot it.

Unknown solar system object. Ruan said solar system objects move rapidly, but the Voorwerp was found on photographic plates made more than 50 years ago, and it hadn’t budged.

Distant, high-redshift galaxy. The redshift was not high enough for the Voorwerp to be at great distance.

Milky Way nebula. Conversely, it wasn’t something in our own galaxy, either, this time because the redshift was not great enough.
It was in examining the spectra, though, that Ruan said a clue was found. The emission lines were strong.

“To get emission lines that are this strong, you need a really, really bright source that emits a lot of high-energy light,” Ruan said, the kind of light you get from gas falling onto a black hole. “This is evidence that this object was produced by a quasar.”

Hanny’s Voorwerp appears as a green blob
in this photo by NASA, ESA, W. Keel
(University of Alabama), and the Galaxy Zoo Team.

There was just one small problem with the idea. There’s no quasar in any of the photos. Ruan said the quasar was probably created when the galaxy merged with a smaller one.

“It disturbs the gas in this larger galaxy, and this gas, some of it, because it’s disturbed it will fall into the center of the galaxy and fall into the black hole,” Ruan explained. This ignited the quasar, but at some point it literally ran out of gas.

“That quasar became quiet again, and it looked like just a normal galaxy, however the gas cloud that the quasar was shining on still appears to be lit up,” he said. “And that is Hanny’s Voorwerp.”

Similar objects have been discovered and are generally referred to as quasar ionization echoes. Ruan said Hanny’s Voorwerp will gradually fade as the ionization of the gas wears off.

The weirdest stars in the universe

Emily Levesque is just finishing her first year on the astronomy faculty at the University of Washington, and her research bailiwick fit perfectly into space oddity night.

Levesque

“I study weird stars, strange stars, the really oddball stars that we can’t easily explain,” Levesque said. Indeed, she started out looking at the odd couple of stars: red supergiants and neutron stars.
Red supergiants are enormous, massive, relatively cool stars. The largest one found so far is so big that it’s surface, if it were plunked into our solar system in place of the Sun, would reach almost out to the orbit of Saturn. Neutron stars are the small, dense remains of supernovae. They are no bigger than a city.

“There’s only one thing that I can do to red supergiants and neutron stars to make them weirder at this point,” Levesque said. “If we put a red supergiant and a neutron star into a binary, and we merge them, we get a very, very weird object.”

The TŻO

The weird object is called a Thorne-Żytkow Object (TŻO) because Kip Thorne of Caltech and Anna Żytkow of the University of Cambridge hypothesized just this sort of thing way back in 1977. Żytkow heard that Levesque was studying red supergiants, and sent an email asking if she’d like to give a shot at spotting a TŻO. It was quite a challenge.

“A neutron star is the size of the city of Seattle,” Levesque said. “A red supergiant is bigger than the orbit of Jupiter. If you embed a neutron star inside a red supergiant it’s virtually impossible to detect.”

As with Hanny’s Voorwerp, the spectra were the key. Inside a TŻO, convection pockets would circulate material and create bizarre chemical processes. As stuff nears the neutron star at the core it would be bombarded with protons, changing it into a different element. Then as it nears the surface of the star, it would decay into yet something else. The process repeats. If the spectrum reveals the presence of elements that you would not normally expect to see at the surface of a cold star, you may be onto something.

Two years ago Levesque and her team looked at 100 red supergiants, and 99 of them appeared normal. The spectrum of one of them, HV 2112, showed unusual concentrations of rubidium, lithium, and molybdenum.

“This was a signature that we’d actually found the first example of a Thorne-Żytkow Object in the universe,” Levesque said.

If true, it means a new way to make stars and a new way to make elements. Levesque said they’re still calling the star a candidate or possible TŻO because of the Sagan Standard that holds that extraordinary claims require extraordinary evidence.

“The evidence that we have is really compelling, but it’s three little blips in a spectrum,” Levesque said. “We desperately want to find more of these, we want to find other ways of detecting them. We’d ultimately love to have a whole set of Thorne-Żytkow Objects, and have a whole set of stars that we can look at that can hold the title of weirdest star in the universe.”

The universe is big, even in small spaces

The universe is pretty vast even in confined spaces. That was the lesson given on opposite ends of the size scale at the most recent Astronomy on Tap Seattle event hosted at Hilliard’s Beer Taproom by University of Washington graduate students in astronomy.

Ethan Kruse

Grad student Ethan Kruse was all set to give a talk that concluded we would never even get out of our solar system because it is way too big. Then a few weeks before the talk Stephen Hawking and friends announced their plan for getting all the way to neighboring star Alpha Centauri in 20 years through a project called Breakthrough Starshot.

“If I’m disagreeing with Stephen Hawking,” Kruse recalled thinking, “I should probably stop for a minute and reevaluate my thesis.”

Kruse remained on point about the mind-boggling scale of the universe. He said that if our Sun was the size of a basketball sitting on the stage of Hilliard’s, Earth would be the size of a sesame seed in the back of the room, 84 feet away, and the orbiting Moon would be the size of a grain of salt. At this scale Jupiter would be a golf ball on the Ballard Bridge and Pluto would be a grain of salt about a kilometer away—about the distance to Bad Jimmy’s Brewing Company, which served as the venue for Astronomy on Tap Seattle for its first year. Alpha Centauri, in this set-up, is some 4,400 miles away—in London or Tokyo.

Kruse pointed out that the fastest spacecraft we have built so far, New Horizons, took a decade to get to Pluto.

“We went from Hilliard’s to Bad Jimmy’s in ten years,” he observed. “Don’t worry guys, we’re going to go to London in 20 years!”

The idea behind Starshot is that a super-light craft with a light sail could be accelerated by lasers to up to 20 percent of the speed of light. Kruse outlined a litany of technological challenges with the concept, including the ability to generate sufficient laser power, creating an adequately reflective material for the sails, being able to accurately aim the lasers at great distances, and shielding the craft from possible collisions with space debris. Still, he concluded, the idea is worth exploring, especially since the same technology could be used to explore the solar system more quickly.

“This is honestly the most realistic thing that anyone has proposed so far for getting to any other star system,” Kruse said.

It will, however, take a great deal of research and development.

“Don’t necessarily count on this before you die,” Kruse concluded. “Space is big.”

Jessica Werk

Professor Jessica Werk, one of the newest hires onto the astronomy faculty at the University of Washington, also used sports equipment to illustrate her talk, “The History of You: The Rather Tumultuous Past of the Atoms in Your Body.” Werk pointed out that atoms are mostly empty space. If the nucleus of an atom were the size of a baseball, the nearest electrons would be a football field away.

After the Big Bang the universe was mostly light atoms: hydrogen and helium and a few others. Where did the carbon and calcium and other heavier stuff we’re made of come from?

“All evidence suggests that these atoms were fused in the cores of very, very massive stars twelve-and-a-half billion years ago,” Werk said. “Since then they have been on an absolutely crazy, long, sometimes violent journey to end up in your body 93 million miles from the Sun on this speck named Earth.”

Those atoms took a somewhat circuitous route to get here.

“Sixty percent of the atoms in your body we at one point outside of the galaxy in the circumgalactic or intergalactic medium,” Werk said. We don’t really know how they got here, but the best theory is that the atoms tend to cool off, and the gas rains back down on the galaxy, collapsing in star formation or becoming part of the debris disk out of which planets form.

There’s some mind-bending scale at the atomic level, too. Werk pointed out that there are 10²³ atoms in a breath of air.

“Each breath-full of air contains more atoms than the number of breath-fulls of air in the entire Earth’s atmosphere,” she said. “What that means is that it is very likely that the last breath of air you just took contained at least one oxygen atom from the first breath of air that you ever took as a human being on planet Earth.”

That reminds us of a recent post by Ethan Siegel on the blog Starts With a Bang, in which he concluded that we all probably share atoms that were once part of King Tut or any other historical figure you might name.

“The matter that makes up your physical body is part of a huge universe that is continually evolving and recycling the material in it into new forms,” Werk concluded.

AoT Seattle celebrates 1st birthday, announces move to larger venue

Astronomy on Tap Seattle last month celebrated its first year of of bringing the latest astronomical research and good beer to interested space geeks. The party was a little bittersweet, as they also announced that the series will be leaving Bad Jimmy’s Brewing Company for the larger Hilliard’s Beer Taproom, another Ballard watering hole.

Astronomy on Tap Seattle packed in the crowds in its first
year at Bad Jimmy’s. The series is moving to the larger
Hilliard’s Taproom in Ballard. Photo: Greg Scheiderer.

The move does not come entirely as a surprise. The early Astronomy on Tap events last spring were well attended, and they’ve grown in popularity to the point where nearly 140 people were sardined into Bad Jimmy’s for the monthly gatherings. Brett Morris, an astronomy graduate student at the University of Washington who is the emcee and one of the co-founders of Astronomy on Tap Seattle, hinted at a move in an interview we posted before the birthday event.

“It’s been a wild ride growing from our initially small size to something that we almost can’t handle,” said Morris. “We’re going to try our best to keep up with it as it grows through our second year.”

Kristin Garofali, another co-founder of AoT Seattle, thanked Bad Jimmy’s for their support over the first year, noting that they even let participants vote to name their imperial Scotch ale (The Big Sipper) and at the birthday party served up a delicious version of it that was aged for several months in rum barrels.

“To see how this has grown has been super amazing,” Garofali said. She added that they hope to keep doing smaller events at Bad Jimmy’s.

Supernova impostor

Breanna Binder gave an interesting talk at the March 23 birthday event, about a supernova impostor that turned out to be an x-ray binary system. An amateur astronomer spotted what looked like a supernova in 2010, but it kept churning out x-rays long after it faded visually. Binder said that’s not how it’s supposed to work.

“Supernova 2010da, not only is it not a true supernova, it may be the youngest possible x-ray binary,” Binder said, noting that it theoretically takes between four and five million years before an x-ray binary begins emissions. They’d seen none prior to 2010. “The 2010 eruption might have been the birth of a brand new x-ray binary, which is something that we had never witnessed before.”
The story was featured on the popular website IFLScience. Binder will give a talk about the supernova impostor at the UW Astronomy Colloquium at 4 p.m. Thursday, May 5 in room A102 of the Physics/Astronomy Building on the UW campus in Seattle.

Planet 9

One of the other more interesting mini-talks of the evening was made by Dave Fleming, who took a look at the possible Planet 9. Astronomers have recently speculated that there’s a ninth planet in our solar system, a so-called super-earth that is somewhere between Earth and Neptune in mass and about 700 astronomical units out. Fleming noted that a fair chunk of the exoplanets discovered so far are in that mass range.

“If there is one of these guys lurking in the solar system, if we could actually detect it with a telescope and send a probe to it, it would give us a huge insight into the planet-formation process,” Fleming said. “If this ninth planet does exist, maybe it’s some relic of the planet-formation process that got scattered out by Jupiter.”

Former planet 9, and more

Morris showed a large number of photos that New Horizons shot at Pluto. He had given a talk back in July, on the day of the mission’s fly-by, and shared the very first pictures it beamed back to Earth. Though it will continue transmitting data for quite some time, we already have a sizable collection of pics from the system. Among the most interesting discoveries from the new batch: a large canyon around the equator of Pluto’s moon Charon that may indicate an underground ocean.

Other talks at the birthday event covered supermassive black holes, fast gamma-ray bursts, how to find a Tatooine, and funky, planet-shaped megastructures.

Happy birthday to Astronomy on Tap Seattle

Astronomy on Tap Seattle has spent the last year confirming that astronomy and beer together make a great combination. We will celebrate AoT’s first year in operation with a gala event at 7 p.m. Wednesday, March 23 at Bad Jimmy’s Brewing Company in Ballard. The free astronomy talks have drawn good crowds from the beginning, and the most recent events have seen attendees packed shoulder-to-shoulder into Bad Jimmy’s.

“It’s been a wild ride growing from our initially small size to something that we almost can’t handle,” said Brett Morris, an astronomy graduate student at the University of Washington who is the emcee and one of the co-founders of Astronomy on Tap Seattle. “We’re going to try our best to keep up with it as it grows through our second year.”

Morris said they had a hunch before they started that the audience was out there. Astronomy on Tap started in New York and has spread to a total of eight cities, and events elsewhere have drawn big crowds. Austin, Texas, for example, regularly attracts 400 people to its events in an outdoor beer garden.

“We knew that there was a big drive for this kind of event, especially in nerdy cities like Seattle, so we knew that the availability of participants was good,” Morris said, “but we didn’t really know if we’d be able to scale up the way we wanted or to reach the number of people that we needed to.”

They set out in hopes of being able to attract 50 people who would attend regularly to hear astronomy talks and enjoy a brew. They’ve accomplished that without any sort of paid advertising.

Brett Morris
Photo: Greg Scheiderer

“It seems that word of mouth among nerds is really effective. The social networks have been all that we needed to get the word out,” Morris said. “The enthusiasm that we’ve had from the audience has been unbelievable and unrelenting, and the beer is quite delicious.”

There will be a special treat at the March 23 event. Astronomy on Tap Seattle participants named one of Bad Jimmy’s beers, a Scotch ale that popular vote dubbed “The Big Sipper.” Several months ago the brewers stowed some of that ale in old rum casks.

“We’re going to tap those barrels for the one-year anniversary and serve this barrel-aged imperial Scotch ale in special commemorative glasses, that you can also purchase, that have astronomy on Tap logos on them,” Morris said.

There will be a series of short talks at the anniversary with updates on astronomy discoveries made in the last year, including the latest photos from Pluto and the possibility of the existence of Planet 9. Morris said that one of the great things about being an astronomer is that when an idea such as Planet 9 comes out, there probably is an expert close by who can lead the discussion about how plausible it is. Astronomy on Tap is essentially an effort to take that discussion public.

“As an astronomer you get to meet a lot of people, daily, who think that astronomy is great and would love to talk to you about space, and would love to talk to you about life in the universe,” Morris said, “but it’s rare that you really encounter people who spend their free time trying to learn more about astronomy and physics, and that really is the core audience of Astronomy on Tap.”

“I am consistently surprised by how many people are passionately interested in learning astronomy and physics at a level deeper than you might find in an astronomy magazine,” he added.

It has been a boon for people who write about astronomy for fun. It’s great to have a monthly topic, and the discussions and trivia contests that are a part of Astronomy on Tap are fun and informative.
The March 23 event begins at 7 p.m. at Bad Jimmy’s in Ballard. You might want to arrive earlier than that to get a good seat! It’s free, but bring beer money.

BOSS and Pleiades figure out the universe

Astronomy these days is something of a tag-team event involving both observers and theorists. We got a look at how it works at the most recent Astronomy on Tap Seattle event at Bad Jimmy’s Brewing Company in Ballard.

Case in point: for a couple of decades cosmologists had been using the cold dark matter theory to explain how the universe evolved from a hot, dense, uniform place right after the Big Bang to the web of galaxies that we see today. The theory worked pretty well, but there were a couple of catches: it predicted that dwarf galaxies would have large central bulges of stars and increasingly dense dark matter at their cores. Neither prediction matched with the observations.

Figuring it out

Look! Up in the sky! Prof. Fabio
Governato makes a point during his
Astronomy on Tap talk Feb. 17 at
Bad Jimmy’s. Photo: Greg Scheiderer.

Dr. Fabio Governato, a research professor in the Department of Astronomy at the University of Washington, said he and a few colleagues, after downing several beers each during an escape from a boring conference, decided to figure out this anomaly. Governato‘s talk at Astronomy on Tap Seattle was titled, “Dark Matter, Black Holes, and other reasons to work with NASA’s fastest supercomputer: Pleiades.”

Eventually, they hit upon the idea that supernova explosions in the dwarf galaxies might push away gas and thus retard star formation, and may also blow dark matter away as well.

“This is very simple physics,” Governato said, “but the problem was to find a numerical experiment that you could run with computers that shows clearly” how it works. They used millions of hours on supercomputers, like NASA’s Pleiades, adding the supernovae into the mix and tweaking the idea until the computer simulation of the cold dark matter theory turned out dwarf galaxies that matched what we actually observe. Their paper about the work was published in the journal Nature, and Governato has some humorous tales about the twists and turns between the work, the publication, and ultimate acceptance of the findings.

His talk also used interesting and sometimes humorous animations to make points. Governato’s movie of a dwarf galaxy formation based on the work is posted below.

Observation

Dr. John Parejko, holding a sample of the
metal plates used in the BOSS survey,
answers questions after his talk. Even
pooches love Astronomy on Tap!
Photo: Greg Scheiderer.

Dr. John Parejko works on the observation side of the equation. Parejko recently was with the Sloan Digital Sky Survey out of New Mexico. His talk was titled, “Detect the Ancient Universe Like a BOSS.”

“BOSS is measuring distances to millions of galaxies to find wiggles from the early universe, but that doesn’t make a very good acronym,” Parejko quipped. BOSS actually stands for Baryon Oscillation Spectroscopic Survey.

The wiggles or oscillations are evidence of interactions that happened right after the Big Bang.

“Patterns in that hot, dense plasma persist to today in the distribution of galaxies in the universe,” Parejko said.

“These are not gravitational waves,” he noted, as the discoveries from LIGO were fresh in the news. “These are actually the interaction between the dark matter and the baryons very early in the universe.”

The process was simple enough, as they took spectra of galaxies and computed their redshifts to precisely determine distances. The challenge was that they had to look at a lot of galaxies, and over the years BOSS examined about a third of the sky and took images of about two million galaxies, measuring the redshifts of about half of those. Using the redshift to pin down distances to and between galaxies, and examining the patterns that emerge, helps astronomers figure out galaxy formation and learn how dark energy is causing the expansion of the universe to speed up.

Part of the tool that BOSS uses is made at the University of Washington, where telescope plates are created for the project. Each metal plate, about three feet wide, has a thousand holes drilled into it, each one corresponding to a specific object in the sky. Humans plug a fiberoptic cable into each hole by hand, and the cable collects the light from targeted galaxies.

Birthday party!

Astronomy on Tap Seattle is organized by astronomy graduate students at the University of Washington. The next event, scheduled for March 23, will celebrate the first birthday of the program. Speakers will update the subjects of their talks from the first year. Attendees will be able to purchase a commemorative AoT beer glass and sample Bad Jimmy’s barrel-aged Big Sipper, a Scotch ale named as a salute to Astronomy on Tap.

Radioactivity is good for you

While most of us tend to think that radioactivity is dangerous, experts say that, like beer, it’s actually good for you in moderation. We learned this while drinking radioactive beer at Bad Jimmy’s Brewing Company in Ballard on Wednesday during the “radioactive edition” of Astronomy on Tap Seattle.

Radioactive beer

UW prof. Rory Barnes makes a point about radioactive beer
during his Astronomy on Tap talk at Bad Jimmy’s Brewing
Company on Wednesday, Jan. 20, 2016. Photo: Greg Scheiderer.

University of Washington astrobiology professor Rory Barnes did the math on the beer. Figuring that a pint is about 90 percent water, carbon is about ten percent of the rest. That works out to 4.5 grams, or about 200 billion carbon-14 atoms. Carbon-14 has a half-life of 5,730 years, which Barnes said means that, in your glass, there’s about one atomic decay every second.

“You are all drinking radioactive beer,” he said. Nobody stopped. I was sipping on a red IPA which was delightful and may have been even a bit more radioactive than the others!

Barnes noted that while we think of Chernobyl or Fukushima when we think about radiation, the process of radioactive decay is pretty important.

Radioactivity is good

“If it weren’t for the radioactivity inside our planet we’d all be dead,” he said. Barnes explained that decay of uranium, thorium, and potassium inside the Earth produces about 50 terawatts of energy, or about 0.1 watt per square meter on the surface. That much energy could run our entire civilization if we could capture it. As it is, it drives geologic processes such as plate tectonics, which helps regulate the amount of carbon dioxide in our atmosphere.

“It’s really important that the planet does a good job of keeping it from building up to too high of a level or dropping down to too low of a level because then our Earth would not be habitable,” Barnes explained. “Without (plate tectonics) the carbon dioxide would either build up and our planet would roast or it would get drawn down and our planet would freeze.”

Earth is in a sweet spot as far as this internal energy goes. Mars generates less than half the energy Earth does and is geologically dead. Jupiter’s moon Io generates a whopping two watts per square meter and is wildly active volcanically. For life, conditions have to be just right.

Radioactivity may lead us to ET

Barnes said that this fact could help guide us to other planets that might be likely to harbor life. The trouble is that in order to determine a planet’s internal energy and radioactivity we would have to look inside a rock that is hundreds of light years away.

“It’s not really obvious how you do that, but that’s what we need to do,” he said. “I’m sorry to say that the answer is that we can’t at this point. This is the limit of our scientific research right now.”

The James Webb Space Telescope will be able to determine the elements in the atmospheres of distant planets. Barnes said it would make sense to use JWST to look at planets that are near where supernovae have occurred, because these stellar explosions spread the heavy elements needed for this sort of planetary energy generation.

Radioactivity and the ages of stars

UW postdoctoral research associate Charli
Sakari explains how the age of a star can
be determined by the presence of radioactive
elements. Photo: Greg Scheiderer.

UW astronomy post-doc Charli Sakari also uses radioactivity in her work. During her Astronomy on Tap talk she explained how she determines the makeup of stars by looking at spectra of the light they emit. Different elements leave a clear signature in the spectrum, absorption lines created when atoms in a star’s atmosphere absorb certain color wavelengths.

“If we measure how dark those lines are we can figure out how much of those elements is present in the atmospheres,” Sakari said.

It is especially informative to look for uranium and thorium.
“Uranium-238 has a half-life of 4.5 billion years, which is about the age of the Sun, whereas thorium-232 has a half life of 14 billion years,” Sakari explained. “These half-lives are long enough that we can use them to date the ages of the oldest stars in the universe.”

The oldest stars have few elements heavier than helium. Younger stars can contain many heavier elements fused in the cores of the generations of stars that preceded them.

Astronomy on Tap Seattle drew a big crowd to Bad Jimmy’s on a rainy Wednesday night. In fact astronomy and beer lovers were packed in so tightly, and were generating considerable warmth, that the staff popped the garage-type doors open to let in a little fresh air. One wag in the crowd speculated that the robust attendance may have been an indicator of the sorry state of network television. We would say that, in eleven months of events Astronomy on Tap, which is organized by astronomy graduate students at the UW, has delivered plenty of good information and tons of fun. The next gathering is scheduled for Feb. 24.

Exoplanets, killer stars, and beer

Astronomers are busy trying to figure out if and when an enormous flare from the Sun might fry us—or at least zap our mobile phones—and also are looking for planets like Earth in orbit around other stars. Those were the subjects of the talks at Astronomy on Tap Seattle last week at Bad Jimmy’s Brewing Company in Ballard. The Kepler Space Telescope figured in both talks.

Rodrigo Luger spoke about the hunt for
other Earths in a presentation at
Astronomy on Tap 5 last week.
Photo: Greg Scheiderer.

University of Washington astronomy graduate student Rodrigo Luger led off the evening’s festivities with a talk titled, “Syzygies in Silhouette: The Search for Alien Earths.” A syzygy is simply an alignment of three astronomical bodies, and when that happens we can detect a planet orbiting a distant star; the planet essentially casts its shadow on Earth, and we can measure the slight drop in brightness of the star.

Luger called Kepler “by far the most successful planet-detection mission.”

“We currently know of more than five thousand potential planetary objects around other stars, which is amazing,” Luger said, noting that, twenty years ago, we knew of maybe a couple. “It’s a fascinating time for exoplanet science.”

Luger pointed out that the number of discoveries is especially incredible when you consider that Kepler is staring at such a tiny patch of the sky.

“If there are thousands of planets (in that field), imagine how many there are in the entire Milky Way,” he marveled.

Where is Earth 2.0?

One frustration is that Kepler has yet to find an exoplanet that is a close match for Earth. Luger said planets our size are a bit tougher to tease out of the background noise that Kepler collects. That may change, he said, when NASA launches the Transiting Exoplanet Survey Satellite (TESS) in 2017.

“TESS is different; rather than looking at a tiny patch of the sky, it’s going to look at the entire sky,” Luger said.

“It’s going to focus primarily on smaller stars,” he added, noting that looking at these makes it “much easier when you want to detect Earth-like planets.”

By coincidence, the day after Luger’s talk the Kepler team announced the discovery of planet Kepler 452b, the closest match yet to Earth.

The Sun takes aim

James Davenport makes a point during his
 talk about solar activity. Photo: Greg Scheiderer.

James Davenport, who just earned his Ph.D. in astronomy at the UW, uses Kepler in his work as well. His main purpose is to better understand our own nearby star, the Sun, and figure out when it might aim a solar flare or coronal mass ejection at us.

Davenport’s talk, “How Stars Keep Active as They Age,” started with a history lesson. Back in 1859 English astronomer Richard Carrington was making daily sketches of his observations of the Sun. He was tracking a huge sunspot and, as he watched it, a couple of enormous bright patches appeared. It turns out that this was the first observation of a solar flare. About twelve hours later, people on Earth saw the most stunning aurorae in centuries.

“The sky lit up red and green, and you could see it as far south as Cuba,” Davenport said. “It was this magnificent, incredible event.” The penny dropped and scientists recognized that the solar flare was the cause of the aurora. The flare created such an electric surge that some telegraph operators suffered burns.

Don’t mess with that

“If a giant solar flare like the one that Carrington observed impacted the Earth today, it would cause trillions if not hundreds of trillions of dollars of damage,” Davenport observed, noting that TV, the Internet, and your mobile phone could get fried. “It could ruin the global economy. It would be a disaster of untold proportions, and there’s noting we can do about it. The sun is just going to hurtle these flares at us whenever it decides to.”

Davenport noted that this isn’t just an academic discussion; a flare of that magnitude barely missed Earth in July 2012.

“If it had been launched a few days earlier and it hit the Earth, we’d still be recovering,” he said.

The Sun is pretty unpredictable, Davenport said. Huge sunspots turn up about every 25 years, but there aren’t always giant flares that go with them. The good news is we’re learning more about the Sun all the time. Data from the Solar Dynamics Observatory is like an HD movie of the Sun that plays 24/7. There is always someone watching. Astronomers also are doing computer models of the Sun to try to figure out more about its processes. Kepler comes in to play by helping us look at thousands of stars of all ages. The younger ones tend to be more active, while older stars like the Sun are relatively serene. It wasn’t always that way for old Sol.

“The young Sun had bigger flares and more of them, and probably dumped out a hundred times more x-rays with every single flare,” Davenport said. “You don’t want to stand in the way of that.”

Cupcakes and beer

Mmmm. Cupcakes

A lifetime of soaking up astronomical minutiae finally paid off for Seattle Astronomy at Astronomy on Tap 5 as our team, the Wild Guessers, took home top honors in both Pluto trivia contests of the evening. The prize: treats from Trophy Cupcakes decorated with images of the highly active Sun. We learned that Bad Jimmy’s strawberry mango hefeweizen goes well with cupcakes. Just watch out for the CMEs: cupcake mass ejections.

Astronomy on Tap Seattle hosts events at Bad Jimmy’s monthly. The next one is scheduled for August 26.

Astronomy on Tap takes a look at the first Pluto pics from New Horizons

Back in the olden days of 1979 I took an undergraduate course in astronomy at the University of Washington. The Voyager spacecraft had just visited Jupiter and the astronomy faculty were positively giddy about the new photos, data, and knowledge coming in from the largest planet in our solar system. The excitement is perhaps even greater as we digest the first images from New Horizons, which buzzed Pluto earlier this week and got our first really close look at what used to be the ninth planet.

“It’s discovering a new planet that we already knew existed,” said Brett Morris, a UW graduate student in astronomy, at a special Pluto-palooza version of Astronomy on Tap Seattle Wednesday evening at Bad Jimmy’s Brewing Company in Ballard.

The icy mountains of Pluto. Photo: NASA-JHUAPL-SwRI.

Morris said the biggest discovery in the first batch of close-ups of Pluto is that, in a section of the dwarf planet’s “heart,” now named “Tombaugh Regio” after its discoverer, Clyde Tombaugh, there are no craters.

“This suggests that the surface is less than 100 million years old,” Morris said. While that may seem like a long time, it’s a mere blink of an eye astronomically and geologically.

“This is really young, and that was a huge surprise,” Morris said. “This is the biggest surprise of the day. The surface must be active.”

He added that we have no idea yet how this could be happening, and that scientists didn’t expect to find such a thing.

Another interesting finding were tall mountains in that photo.

UW grad student Brett Morris talked
about the history of Pluto and the first
photos from New Horizons at
Astronomy on Tap Seattle July 15.
Photo: Greg Scheiderer.

“We believe that these mountains are water-ice mountains eleven thousand feet tall,” Morris said, explaining that ice of methane or carbon monoxide would crumble at that height, but that water ice, in a place as cold as Pluto, would be as hard as rock.

“Imagine an ice cube the size of Mt. Rainier,” Morris said. “That’s what we’re looking at.”

Pluto’s largest moon, Charon, has material at its north pole that is darker than the rest of its surface which, like Pluto’s, also appears to be active. They’ve also spotted a large canyon on Charon.

“That canyon is twice as deep as the Grand Canyon, it stretches across a significant chunk of Charon,” Morris explained. “It’s either a really big crater or a valley carved out by something.”

The small moon Hydra appears to be made entirely of ice.

“This is a 30-mile hunk of ice sitting out there orbiting Pluto,” Morris said.

The photos returned by New Horizons are far better than any images of Pluto captured by the Hubble Space Telescope.

“The Hubble Space Telescope tried really hard to give us good images of Pluto, but that’s really difficult because it’s so far away,” Morris said. The telescope was able to see bright and dark regions on Pluto, but that was about it. Hubble also was used to search the Pluto system for rings, moons, and other objects that could be a hazard to the speeding spacecraft.

“At 15 kilometers a second, if there’s a piece of rice in your way it will destroy your spacecraft,” Morris noted. Four of Pluto’s five known moons were discovered by Hubble during this process.

Morris noted that it’s going to take a while for New Horizons to send us all the data it has collected during its flyby of Pluto. The spacecraft is equipped with what he says is essentially a 200-megabyte modem that only contacts Earth every once in a while.

“This is worse than AOL!” he quipped. We should keep receiving photos and data from New Horizons through November of 2016, so we have a lot of cool new discoveries to look forward to. May we be fortunate enough to enjoy a cold brew with each one of them!

Cannibal galaxies and asteroid mining

Our galaxy is a cannibal, and we have quite an appetite for resources in our own little corner of the Milky Way, too. That’s what we learned at the latest Astronomy On Tap event in Seattle, held last week at Bad Jimmy’s Brewing Company in Ballard.

John Lurie talked about the cannibal
Milky Way galaxy at Astronomy on
Tap Seattle. Photo: Greg Scheiderer.

John Lurie, a graduate student in astronomy at the University of Washington who studies the structure of the Milky Way, started his talk with a bit of history. For millennia, up until recently when light pollution made the Milky Way invisible to a great many of us, people saw it and made up stories about what it was. To Lurie’s mind, some of the violent images of Greek mythology seem fitting.

“Our Galaxy is actually a cannibal, and it likes to eat other galaxies,” he said. “Not only that, but the entrails of its victims are strewn across the heavens.”

We didn’t know much at all about the Milky Way until Galileo pointed his telescope at it four centuries ago and wrote down that he saw individual stars.

“Up until the beginning of the 20th century that was basically it,” Lurie said. “The entire universe, as far as we knew, was contained in the Milky Way.”

New learning

Fast forward to Edwin Hubble, who used a much larger telescope, the 100-inch at Mt. Wilson, to look at cepheid variables. Hubble calculated that what was then known as the “Andromeda nebula” was about 2.5 million light years distant—way too far away to be part of our galaxy. It was another galaxy.

If this ball were the Sun, the next nearest star would be in
New York. Photo: Greg Scheiderer.

Galaxies seem awfully far-flung to be cannibalizing each other, but Lurie explained that they’re actually relatively close together. He noted that if the Sun were a yellow ball a bit smaller than a pint beer glass (an apt analogy given the locale of the talk) our next nearest stellar neighbor would be in New York. However, if the disk of the Milky Way galaxy were represented by a frisbee, the next nearest major galaxy would be inside Bad Jimmy’s, a mere 20 feet away. In addition, between us and Andromeda are a number of dwarf galaxies. Astronomers have found streams of stars that are evidence that the Milky way has collided with one of them, the Sagitarius dwarf galaxy.

“That’s why I claim that our galaxy is actually a cannibal,” Lurie said. “It’s in the process of eating this galaxy. Gravitational tidal forces of the Milky Way are tearing the stars off of this dwarf galaxy and they’re being strewn out into space.”

Bigger fish

Lurie says that when it comes to cannibal galaxies there’s always someone bigger out there.
“The Andromeda galaxy is coming to get us,” he said. “It’s a little bit bigger than us, and we’re on a collision course.”

Not to worry. It won’t happen for another four billion years or so, and since individual stars are so spread out, the likelihood that two would collide is pretty small. Some stars could get flung out of the galaxy, but mostly the Milky Way and Andromeda will eventually coalesce into one big galaxy.

Mining asteroids

Matt Beasley of Planetary Resources
explained the best types of asteroids
for mining useful materials.
Photo: Greg Scheiderer.

Closer to home folks are thinking of mining nearby asteroids for the valuable materials they contain. Dr. Matthew Beasley, a senior engineer at Redmond-based Planetary Resources, gave a talk titled, “Resources on Asteroids: What’s There, How Much, and Why?”

Beasley noted that there are 872 known asteroids of about one-kilometer orbiting in near-Earth space, and perhaps as many as 20,000 smaller ones down to about 100 meters. That’s a lot of potential targets for asteroid mining.

Why go to the trouble?

“Asteroids are extremely rich in useful materials,” Beasley said.
There are three main types of asteroids. Beasley explained that the first ones Planetary Resources will target are C-type carbonaceous asteroids. These make up about 75 percent of all asteroids, but only about six percent of the known near-Earth asteroids. They’re hard to spot because they’re so dark in color, like a lump of black clay. C-type asteroids are around 20 percent water by mass, and that’s what makes them appealing. Water is handy for space explorers to drink, and it can be broken down into hydrogen and oxygen for spacecraft fuel.

“One 75-meter C-type asteroid full of water could have fueled all of the shuttle missions,” Beasley noted. It will cost a lot less to pick up water and fuel in space than it does to launch them into space from Earth.

The second target type of asteroid is the M-type, which is heavily metallic. M-type asteroids contain virtually no water, but are rich in metals such as nickel, iron, and platinum, and maybe some silicates.

“One 500-meter metallic contains more platinum than has ever been mined by humanity,” Beasley said, adding that all of the platinum on Earth probably got here through collisions with asteroids. Platinum-group metals are highly sought after for electronics and other manufacturing, and all of the metals could be useful for building things in space. As with the water, it’s a lot less expensive to find it out there than it is to take it with you.

A third common asteroid is the stony S-type. These contain no water, some metals, but basically are between 75 and 90 percent silicates.

“They’re a little light on volatiles and organics, lots of rock,” Beasley said, noting there’s little interest in this type of asteroid. “Basically, they’re fill dirt.”

Game of Thrones and black holes at latest Astronomy on Tap

The extreme seasons on the popular HBO series Game of Thrones and supermassive black holes were the subjects of talks at the most recent Astronomy on Tap event held at Bad Jimmy’s Brewing Company in Ballard.

AoT vs. GoT: Reasons for the (Extreme) Seasons

Russell Deitrick makes a point during his talk at Astronomy on
Tap II at Bad Jimmy’s Brewing Company. Photo: Greg Scheiderer.

Russell Deitrick is an graduate student in astronomy at the University of Washington, studying models of the dynamics of exoplanets in multi-planet systems. He is particularly interested in how interactions between planets with high eccentricity and high mutual-inclination might affect habitability of those planets. That, it would seem, makes him the perfect one to figure out what could cause the sort of long, severe, and unpredictable seasons the characters on Game of Thrones experience.

Deitrick started with a quick primer on what causes seasons. The main cause is the axial tilt, or obliquity, of the planet. Earth, for example, has an axial tilt of about 23 1/2 degrees, and when a pole is inclined toward the Sun its hemisphere enjoys summer.

There are several ways to mess with the seasons, Deitrick explained. Our Moon stabilizes precession—the wobble of the orbital axis like a top—so if a planet doesn’t have a large moon, precession would be greater and there would be more variance. You could alter the orbit itself, making it highly eccentric.

Other factors that can change climate include volcanism, solar variability, or having a planet in a binary star system.

Deitrick ran computer models in which all of these varied wildly. The simulations didn’t match the show.

“Eccentricity can’t really explain the duration of the seasons on Game of Thrones,” Deitrick said. “If you’re at high eccentricity, you may have a very long winter, but you’re going to have a correspondingly short summer, and the seasons are going to be the same length.”

He noted that changing the obliquity of the axis can explain everything except the long duration of the seasons. Volcanos can create long seasons, but Deitrick said that doesn’t fit in with the show.

“The problem with the volcanic winter is that it’s possibly too random,” he said. “The fact that the seasons are quasi-predictable suggests that it probably isn’t related to volcanos.”

He said solar variability takes to long to create climate change on the short time scale of a season, and a binary star system doesn’t appear to be part of the story in Game of Thrones.

“You’d think they’d mention somewhere in the series that there were two suns,” he said.

“None of these can explain that long night, that generation of darkness,” Deitrick added.

“The seasons on Game of Thrones probably can’t be explained by a single theory,” Deitrick concluded. “So they’re probably magic.”

Supermassive black holes: size matters

Michael Tremmel is working on figuring
out how supermassive black holes came to be.
Photo: Greg Scheiderer.

Michael Tremmel, another UW astronomy grad student, took on an equally mysterious if less fictional topic in his Astronomy on Tap talk: supermassive black holes.

Tremmel explained that an ordinary black hole—one of between one and 10 solar masses—is the result of simple stellar evolution.

“When a massive star runs out of fuel and explodes in a supernova, the core of the star continues collapsing and forms a black hole,” he said.

The problem is that supermassive black holes can be of billions of solar masses and could not have formed in the same way.

“It’s still an open question where these black holes came from,” Tremmel said, “but we think that they must have formed very, very early on in the universe when the first stars that exist were beginning to form. Before there were galaxies, before there were stars, there were supermassive black holes.”

We’ve never seen a black hole because they don’t emit light. Their gravity is such that even light can’t break free. But the evidence that they exist is plain. Tremmel explained that we have observed stars orbiting rapidly around the center of our own galaxy. By gauging the trajectories of these stars we reach one conclusion about what they are orbiting.

“This object must be really, massive, and really, really small,” he said. “The only thing this thing could be is a black hole that is a billion solar masses.”

We’ve seen the evidence of black holes in other galaxies by catching the glow of gas as it is consumed by supermassive black holes.

“This gas is flowing in, spiraling around, and becoming very, very hot,” Tremmel noted. “As that gas gets really hot it emits a lot of light.”

Tremmel said it’s an exciting time for his field of study, trying to figure out more about the formation of supermassive black holes.

“These relatively tiny objects within a galaxy are a true mystery still for astronomers,” he said.

Gamma ray bursts, galaxies, exoplanets, and beer

Back in 1979 when I was an undergraduate at the University of Washington I took an introductory course in astronomy to fulfill some science credit requirements. The two Voyager spacecraft had just visited Jupiter and the faculty in the astronomy department seemed practically giddy about all of the new data received and textbook re-writing to come. These days, given the number of exciting missions returning information from the near and far reaches of the solar system, it seems we’re learning something new about the cosmos almost every day.

Case in point: earlier this week a trio of UW astronomy graduate students put on the first Astronomy on Tap event in Seattle, each giving a mini-lecture about their current research. Two of them had news fresh out of the headlines.

Zapped by gamma rays

Kristen Garofali was first up with a talk titled “To GRB or Not to GRB.” The GRB in this case stands for gamma ray burst.

There was a full house Wednesday at Bad Jimmy’s in Ballard for
the first Seattle Astronomy on Tap event. Photo by @AoTSeattle.

“Gamma ray bursts are cosmic lighthouses,” directional beams that Garofali explained result from the formation of a black hole. “When the black hole forms there are two jets of energy emitted that are really high-energy.”

Last week, for the second time in less than a year, scientists thought they had detected a GRB from our closest galactic neighbor, M31, the Andromeda galaxy. This would have been a first; we’ve never detected a GRB so nearby before. The nearest have been billions of light years distant, while M31 is a mere 2.5 million light years away from Earth.

Both the event last May and the one last week turned out not to be GRBs. Garofali noted that there are other objects out there that emit gamma rays, but these don’t look at all like whatever was detected coming from the neighborhood of M31 last week.

“It’s too bright to be a transient or an ultraluminous x-ray source,” she said. “It’s too faint, however, to be a gamma ray burst.” Even so, Garofali finds the discovery and the mystery exciting. “It could open our eyes to some new process that we haven’t thought about before,” she said.

Garofali said the reason we should care about this is that gamma rays are nasty things. At the very least, one would foul up your cell phone reception, and a strong burst could cause mass extinction on Earth. In fact, there is some scientific speculation that a GRB may well be responsible for at least one of the mass extinctions that have hit our planet. However, to do that the GRB would have to come from relatively close by and be aimed right at us. The odds of that happening are extremely long, but not zero.

Astronomy porn

Talk number two by Nell Byler was titled “Andromeda, So Fly, So PHAT.” She wasn’t using dated slang, but rather was talking about the Panchromatic Hubble Andromeda Treasury, a key tool for her work studying stellar populations. PHAT has taken up a lot of the Hubble Space Telescope’s time; the treasury was created from some 7,400 Hubble images involving 936 exposure hours. The collected data has resolved more than 117 million stars in our neighboring galaxy. The UW’s Julianne Dalcanton is the principal investigator for PHAT.

This PHAT portrait of M31 is a mosaic of more than 7,000
Hubble Space Telescope images. Photo: NASA; ESA;
 J. DALCANTON, B.F. WILLIAMS, AND L.C. JOHNSON/
UNIV. OF WASHINGTON; THE PHAT TEAM; R. GENDLER.

Byler showed a great deal of “astronomy porn”—stunning Hubble images from the project. They’re more than just pretty pictures; Byler said PHAT has the potential to reveal much about star formation, stellar evolution, and a host of other questions about how galaxies work.

“Even though we’re looking at stars within another galaxy it provides a lot of insight for galaxies that we can’t resolve and for our own galaxy, which we think is pretty similar to Andromeda itself,” Byler said. “And there’s lots more science to be done.”

Little green men

Brett Morris closed the evening with a talk titled “Dear Grandpa.” Morris is an astrobiologist, which his grandfather thinks is a pretty fishy undertaking involving the cover-up of the existence of extraterrestrials. Morris is hoping to find ETs, though, and on the very day of Astronomy on Tap the news wires were abuzz with new information about subsurface oceans on Jupiter’s moon Ganymede and on Saturn’s moon Enceladus, both of which could be havens for life. Kenneth Chang’s article in the New York Times provides excellent coverage.

Water vapor geysers erupt from the south pole area of
Saturn’s moon Enceladus. Photo: NASA/JPL.

“Enceladus has what we call cryovolcanoes; they’re volcanos that shoot out water,” Morris said.

“I personally think that this is the best chance to look for life elsewhere in our solar system because we can send a spacecraft that just orbits this moon and picks up the water as it shoots out of the moon,” he said. “Could it get more convenient? We don’t need to dig at all!”

Morris explained how the Kepler Space Telescope hunted for planets around other stars, though he bristled a little at the fact that when one is discovered similar in size to our home world it is invariably called “Earthlike.”

“Those have very broad, flimsy definitions,” he said, noting that Venus, which is practically our twin in size and mass, could be called Earthlike, but it would not be a nice place to visit. Morris is excited for scientific advances that will help us get a better idea of what exoplanets are truly like, and to identify which ones might harbor life like us.

The Astronomy on Tap event was well attended, with more than 60 people jamming into Bad Jimmy’s Brewing Company in Ballard (which pours a lovely IPA, by the way). The talks were well received and games were enjoyed, even though our team, nicknamed “Hubble Trouble,” did not win any cupcakes donated by Trophy Cupcakes. The organizers plan to be back with more events. Follow them on Twitter at @AOTSeattle. Also watch Facebook, where they hope to set up a page soon.