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.

White spots on Ceres may be salt

The first big surprise as the Dawn spacecraft was approaching the dwarf planet Ceres earlier this year were bright white spots on its surface. Now that Dawn has been orbiting Ceres for six weeks, a theory has emerged about what the spots are: salt.

Dr. Tom McCord, a planetary physicist who is co-investigator on
the Dawn mission, spoke about the exploration of Ceres Saturday
during an Astronomy Day event at the Pacific Science Center
in Seattle. Photo: Greg Scheiderer.

Dr. Tom McCord, a co-investigator on the Dawn mission and director of the Bear Fight Institute, a research organization based in Winthrop, Wash., spoke at an Astronomy Day event Saturday at the Pacific Science Center in Seattle. Here’s why he thinks the spots could be salt.

McCord explained that Ceres is differentiated: it has a rocky core, a water-ice mantle layer, and a dirty crust. He noted that they’ve learned a lot from the early photographs.

“There’s a lot of evidence of activity; many craters, an older surface, but not as old as the object, so something obliterated the craters from early on,” McCord said. “Distorted features, so the surface had to have been warped.”

“There are domes, things pushing out from the inside,” he continued, “and bright spots that suggest that material from inside has come to the surface in some sort of volcanism.”

In addition, McCord explained that ground-based telescopes have detected water vapor that comes and goes in the area of Ceres. Liquid water from the interior of Ceres may be being ejected to the surface, where it wouldn’t last long.

This image was taken by NASA’s Dawn spacecraft of dwarf
planet Ceres on Feb. 19 from a distance of nearly 29,000
miles (46,000 kilometers). It shows that the brightest spot
on Ceres has a dimmer companion, which apparently lies
in the same basin.
Photo: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

“What that would do is leave a residual salt deposit, so these bright spots could be salt deposits that accumulated around vents—volcanos—where the water is coming through,” McCord speculated.

He stresses that the work on data from Ceres is still in its early phases, joking that, “We scientists don’t know entirely what we are seeing.”

McCord said the evidence of geological activity has been the most interesting finding so far at Ceres.

“It has been active and may well still be active today,” he said. “That’s exciting to a physicist because you really want to know whether these processes that you conjure up in your models really have happened and, we hope to learn, to what extent and over what time scale.”

Ceres is a great target for study because it may hold clues to how planets form. It is the only dwarf planet in the inner solar system and is the largest object in the asteroid belt. With a diameter of 590 miles, it’s about as big as Texas.

“This is a very large small planet,” McCord said. Ceres comprises about a third of the mass of all objects in the asteroid belt.

The Dawn spacecraft is unique, according to McCord.

“It is the only interplanetary spacecraft that uses ion propulsion, and that is the only reason we are able to orbit two different objects in the outer solar system and still have enough fuel to go on,” he said. Dawn launched in 2007 and studied the asteroid Vesta for 14 months in 2011 and 2012 before heading to Ceres.

“Dawn is really a pathfinder for this kind of multiple-object extended exploration,” McCord said.

Dawn will be collecting data at Ceres for another year to 18 months. McCord said the spacecraft has four momentum wheels and needs three of them to hold itself in stable position. However two of the wheels have failed, so mission scientists are using the craft’s thrusters as a substitute. The hydrazine fuel will eventually run out, and Dawn will tumble about in a stable orbit around Ceres for a long, long time.

Battle Point sundial project nearing completion

Seattle Astronomy was excited to get a note over the weekend announcing that the Battle Point Sundial Project is nearing completion. The Battle Point Astronomical Association (BPAA) reports that its spectacular, 12-foot-tall equatorial bowstring sundial should be installed near its Edwin E. Ritchie Observatory in Battle Point Park on Bainbridge Island within the next few weeks, depending on the delivery schedule of the sundial’s fabricator.

The foundation is prepared for the Battle Point Astronomical
Association equatorial bowstring sundial. From L-R: Dylan
 Sievertson (PHC Construction, built the foundation); Nels
Johansen (BPAA Vice Pres); David Browning (Sundial Engineer);
Bill Baran-Mickle (Sundial Artist/Designer). Once the
foundation was aligned and leveled, more concrete was
poured around it to lock it in place. The Edwin E. Ritchie
Observatory is in the background. Photo: Malcolm Saunders.

The BPAA has had this project on the drawing board for a long time. After slowly collecting funds over the years at their planetarium shows and other events, they reached a critical mass two years ago. Committed volunteers started to drive the project, and in late summer of 2013 they launched an Indiegogo campaign to raise $17,000 to bring their kitty up to the $30,000 they needed to build the sundial and install it in the park. The campaign drew some 75 donors, including Seattle Astronomy, and though it fell somewhat short of its goal, the attention the campaign attracted drew other outside funding, including a $1,000 grant from the North American Sundial Society, and BPAA amassed enough cash to move ahead with the project.

Their original goal was to have the sundial installed and dedicated by last spring, but they ran into some delays as sometimes happens with construction projects. They’re on track now with the foundation in place and ready for sundial delivery, and the sundial itself is fabricated and painted and ready to roll.

The sundial will be more than just a celestial timepiece. It will be a work of art and a conversation starter, and it will be a focal point for the BPAA’s facilities, which include the Ritchie Observatory, home of the 27.5-inch Ritchie Telescope and the John H. Rudolph Planetarium.

General relativity explained

Cool news from the Seattle Astronomical Society, which just announced that the program for its April meeting will be a talk by Dr. Jeffrey Bennett, author of What Is Relativity?: An Intuitive Introduction to Einstein’s Ideas, and Why They Matter (Columbia University Press, 2014).

Bennett has spent much of the last 30 years at the University of Colorado, where he remains an adjunct research associate with the Center for Astrophysics and Space Astronomy. These days he is mainly a writer and he has embarked on a “Relativity Tour” this year, celebrating the centennial of Einstein’s revolutionary ideas. Bennett’s basic premise is that general relativity is not all that difficult to grasp, and his goal is to bring relativity out of the realm of obscure science and help us understand it and the impact it has on our lives.

Oddly enough, it appears that my cats understand relativity. Followers of the Seattle Astronomy Facebook page recently saw the photo below of their demonstration. People trying to help others understand general relativity often ask them to imagine a bowling ball on a bed sheet. In this case Archie and Theodolinda used themselves as the massive objects, and the down comforter represents space-time. The green object in the background may be Neptune.

Bennett’s explanation may not be simple enough for cats to understand, but it is advertised as suitable for anyone from middle school on up. Bennett has taught young kids, and in addition to scholarly textbooks and science tomes for adults, he has written a series of children’s books featuring the outer space adventures of Max the dog. To gear up in advance of the talk pick up What Is Relativity? by clicking this link or the photo above. Links to Bennett’s other books are below.

The Seattle Astronomical Society talk will be at 7:30 p.m. Wednesday, April 15 in room A102 in the Physics/Astronomy Building at the University of Washington in Seattle. In addition to SAS, the Relativity Tour is sponsored by Big Kid Science, Columbia University Press, Fiske Planetarium, and Story Time From Space.

More materials

Jeffrey Bennett website

Books by Bennett

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.