Okay Hubble, You're Safe To Go

The AAVSO has your back.

It's not always obvious why I find observing cataclysmic variables particularly fun and exciting. I admit some nights it seems like a lot of effort for little return. Other nights a whole slew of stars I monitor will all be in outburst at the same time, like so many thermonuclear explosions ignited in space for my viewing pleasure. Occasionally, we get asked to monitor specific stars as part of an AAVSO campaign, in collaboration with professional astronomers in need of specific data.

That was the case early this week. Paula Szkody, an astronomer from the University of Washington, and her team had been approved for time on the Hubble Space Telescope. They planned to observe the cataclysmic variable GW Librae on Wednesday in ultraviolet wavelengths with the Cosmic Origins Spectrograph (COS). What they needed from us was pretty simple, but very important. They wanted to be absolutely sure the star was in its faint state, quiescence. The COS is the most sensitive ultraviolet spectrograph ever flown on Hubble. They can't look at anything as bright as 14th magnitude with it without risking damage to the detector. If GW Lib suddenly erupted while HST was pointed at it very bad things could happen, and there are no more scheduled servicing missions.

A handful of observers, including me, were able to observe the system in advance of the HST run, and we reported it was safely inactive at the time. This enabled the mission team to give the go ahead for the HST observations. Me, personally, I dragged myself out of bed at 3AM to get my early morning observation of GW Lib, a star I don't normally monitor because it is so far south, at -25 degrees declination. But, I am well aware of the fact that there aren't that many observers out there willing to do this kind of stuff, and on any given night I might be the only one anywhere looking at the star I am observing. I didn't expect any big reward; just the satisfaction of knowing I did my little part to enable science to push the boundary of our knowledge another inch forward.

Today, I got an email from Paula Szkody, addressed to all seven of the observers who contributed data, thanking us for enabling the team to get the HST COS observation they wanted. She wrote:

"Hi -
I just wanted to thank all you great observers for the data you took in the last few days on GW Lib (esp last night when it was critical to get a magnitude to HST this morning). Your observations enabled HST to give the go-ahead for the COS UV observation to proceed tonight. THANK YOU! "

You mean they wouldn't have pointed that big ole satellite at GW Lib without us telling them it was okay?

That's right. Pretty cool, eh?

New and Improved! The Hubble Sequence Revised

File this one under "one more thing that requires us to re-learn what we learned in school about galaxies". You've probably seen the "Hubble sequence" in astronomy books. It looks like a tuning fork, and has been thought of as a way not only to describe and classify galaxies, but possibly explain their evolutionary tracks as well. The original scheme, named for Edwin Hubble, was based on galaxies relatively close by in space.

With more powerful modern telescopes able to image galaxies at much greater distances, and further back in time, astronomers have been constructing a new Hubble sequence for populations of galaxies that existed when the Universe was much younger, and find it to be remarkably different. The image below demonstrates the differences in galaxy morphology and the proportion of types between local galaxies and those six billion light years away.

Image credit: NASA, ESA, Sloan Digital Sky Survey, R. Delgado-Serrano and F. Hammer (Observatoire de Paris)

(Click on the image to enlarge)

The two sections show how many more peculiar shaped galaxies (marked Pec) are seen among distant galaxies, as opposed to local galaxies. Researchers found that 3 percent of galaxies were elliptical (marked E), 15 percent lenticular (marked S0), 72 percent spiral (marked Sa to Sd, or SBb to SBd) and 10 percent peculiar (marked Pec) among local (younger) galaxies.

The bottom half of the image represents the make up of the distant galaxies (six billion years ago), and shows much larger fraction of peculiar galaxies. The census found 4 percent of distant galaxies were elliptical, 13 percent lenticular, 31 percent spiral and 52 percent peculiar. 

This implies that many of the peculiar galaxies ultimately become large spirals. This is contrary to the widely held opinion that galaxy mergers result in the formation of elliptical galaxies. According to the 'spiral rebuilding' hypothesis, devised by the astronomers François Hammer, Rodney Delgado-Serrano and their group, this is due to the large number of major, gas-rich galaxy mergers between galaxies that were previously labeled 'peculiar' in the distant Universe. They believe the Andromeda galaxy formed in this manner. 

Collisions and mergers between galaxies give rise to enormous new galaxies and, although it was commonly believed that galaxy mergers decreased significantly eight billion years ago, this new result also suggests that mergers were still occurring frequently after that time; up to as recently as four billion years ago.

Another example of the scientific process at work. Our ideas, and the things we thought we knew before, get revised and improved as more and better data becomes available. And publishers must continuously update text books to reflect today's understanding of the Universe we live in.

Impressions from the 215th AAS Meeting in Washington, DC

The American Astronomical Society held its 215th annual meeting in Washington DC January 3-7. Now with the talks all done, the posters taken down and the tables and chairs packed away, I thought I’d give a brief overview of my own impressions from the meeting.

I think everyone who went to the meeting was eagerly anticipating the first results from the Kepler mission. They did not disappoint. Five new exoplanets, a mysterious, possibly new type of object too hot to be a planet, but not a star, (or is it?), reports on the excellent performance of the detectors and space craft, and asteroseismological results, all from the first months of observations.

"Kepler is working so amazingly well," says Berkeley's Geoff Marcy, a member of the Kepler science team, "that the light curves look like they come from a textbook, not a real instrument."

What I found even more impressive was the immediate release of science papers by the team, with a dozen significant papers hitting the astro-ph server within hours of being announced at the AAS meeting. The mission scientists were ready and loaded for bear right out of the shoot. We are gong to be hearing about results from this exciting mission for years and years.

The Hubble Space Telescope is in good hands. Dr. John M. Grunsfeld was appointed Deputy Director of the Space Telescope Science Institute (STScI) in Baltimore, Md. on January 4th. STScI is the science operations center for NASA's Hubble Space Telescope and the James Webb Space Telescope planned for launch in 2014.

If John’s name sounds familiar it’s because he’s a veteran of five space flights, including three servicing missions to the Hubble. He’s logged over 835 hours in space, including eight space walks, totaling nearly 60 hours. He succeeds Dr. Michael Hauser, who stepped down in October.

There were plenty of new science results presented at AAS demonstrating that Hubble has been reborn again, and is in fact better than ever. Images of the earliest galaxies ever recorded were among the hot Hubble news this week. "We're just at the beginning of this story," said Grunsfeld. "It's incredibly thrilling to see these new instruments working and delivering results."

One of my favorite 2009-2010 stories is the enigmatic variable star epsilon Aurigae. Epsilon Aur made the news at AAS on several fronts. Talks from some of my colleagues on results from the Citizen Sky project were given on Tuesday, and results from observations in the far ultra-violet using the Spitzer Space Telescope were also big news.

Observations by Dr. Don Hoard and collaborators using Spitzer revealed the presence of a disk about 8 astronomical units in diameter, as expected. What was unexpected was that it consists of relatively large particles mostly the size of sand grains, not the usual microscopically fine space dust. Observations also indicate the presence of a smaller, very hot star at the center of the disk, probably spectral type B.

Hoard and his colleagues have proposed a new model to explain these observations. A key element is that the primary, a bright F supergiant, is much less massive than previously thought. In their model the primary started off at around 10 solar masses (as opposed to the 15 or 20 previously assumed) and has since blown off much of that via its stellar wind. The B star companion has only about 6 solar masses, and shines much dimmer. According to Hoard and colleagues, the dark disk is not that of a newborn star still accreting material. The disk is made of material that the B star gravitationally captured from the evolved primary’s wind.

"It was amazing how everything fell into place so neatly," said collaborator Steve Howell of the National Optical Astronomy Observatory. "All the features of this system are interlinked, so if you tinker with one, you have to change another. It's been hard to get everything to fall together perfectly until now."

There is some controversy about this and still a lot to be learned. Arne Henden, director of the American Association of Variable Star Observers, (and my boss), emphasizes that the mystery of epsilon Aurigae has not been solved yet. “We’re nearing the middle of the eclipse, and lots of interesting things will happen over the next year. There are still things about this system we don’t understand.”

The blogosphere was alive and kicking throughout the meeting. New media coverage of the fast breaking news was phenomenal. First and foremost, I have to thank and congratulate Pamela Gay and Fraser Cain for the excellent coverage of the press conferences and many of the invited talks on Astronomy Cast Live. I wasn’t able to attend the meeting, but thanks to the live coverage I feel like I got to see a lot of the events I would have wanted to cover if I was there in the flesh. I was able to watch new NASA Deputy Director, John Grunsfeld, live and share in the audience’s approval and excitement. The 21st century will see a lot more remote coverage of science news, and Astronomy Cast Live is showing the way.

Twitter was also abuzz with tweets coming directly from attendees. There was a wave of tweets rolling in as Charlie Bolden, the new NADSA administrator, gave the keynote address to a packed house. Every time he made an applause-worthy or controversial statement, Twitter lit up with quotes and comments from people in the conference room.

Bloggers from Universe Today and elsewhere covered all the big stories and had blogs posted by the end of the day on everything exciting and new.

The print press was also there in full force. I have to admit, Bob Naeye, the Editor in Chief of Sky and Telescope magazine impressed me at the press conferences with his knowledgeable and penetrating questions. He appeared well versed in what ever the topic of the moment was, from Gamma-Ray Bursts to stellar evolution to exoplanet searches and results. Bob was everywhere, asking multiple questions of numerous speakers at just about every press conference I witnessed.

By and large, scientists are doing better than ever at getting the word out about the scientific method, the universe we live in and the ‘secret lives of astronomers’. There are still those PhDs who can’t give a presentation, and should take a public speaking 101 course, but every discipline has people who just suck in front of a microphone. I give a big Simo-wag-of-the-finger to those astronomers who come ill prepared to give a talk or stammer through press conferences; you know who you are. Fortunately, they are the small minority.

I think the 3,000 people attending this meeting would agree that most of these astronomers are succeeding admirably informing the public and each other in entertaining and enlightening ways. The AAS is not a bunch of geeky nerds with pocket protectors in lab coats. They are real people doing real science in the real world, really well. Really!

Hubble's Amazing Rescue

PBS sent me an advance copy of the NOVA program 'Hubble's Amazing Rescue' which airs Tuesday, October 13, 2009 at 8PM Eastern time on PBS. At first I thought, "Great, another hour-long show of guys practicing space walks in a swimming pool". I couldn't have been more wrong.

What you get is truly an insider view to the preparation, dedication and innovation required to carry out the most sophisticated set of space walks and tasks ever performed by human beings in space. These astronauts spent two years of their lives preparing to repair and upgrade mankind's favorite telescope for the last time ever. Like Super Bowl contenders, when game day comes you get one chance, that's it.

The stars of the show are undoubtedly the two astronauts who made the space walks and Hubble herself. But like any great team, it takes dozens to hundreds of people to make it all work. I actually enjoyed the underwater practice sessions. We got to see how they made a plan, ran through it underwater, made corrections based on practice experience and revised the plans. The engineers who were designing and redesigning the special tools sometimes worked day and night to get things ready for the next practice session.

I'd never thought much about it before, probably because I didn't realize just how long some of these space walks lasted, but these astronauts spend up to eight hours floating around in those suits and you can't take a ham sandwich with you for lunch. There are no potty breaks either. All this reminded me of one of my favorite captions of all time.

In space you wear some mighty thick, clumsy gloves. Yet these people were tasked with removing dozens and dozens of little screws without dropping a single one. A loose screw inside the space telescope would be a disaster.

Speaking of disasters, just going up in the space shuttle takes a special kind of person. You have a one in seventy chance of not coming back.

The movie takes us through the two year preparation. We get to know these brave astronauts and many of the ground team. Finally, launch day comes and everyone is ready to go. Once in space, the shuttle crew wastes no time grabbing Hubble and gets down to business. Seeing the giant space telescope sitting in the cargo bay of the shuttle always surprises me. The Hubble Space Telescope is gigantic! I don't know why, but I never think of it as being that huge. After all, it's a satellite right?

As with all the best laid plans of men, not everything goes off without a hitch. Obviously, we are beginning to see the results of this servicing mission in new images from Hubble, so you know they completed the job and made it back home safely; but there are some suspenseful moments in the mission that I will not spoil for you. Watch the movie Tuesday, or make sure you record it on your DVR. You won't be sorry. It's an amazing story about amazing people doing amazing things to keep our most amazing telescope ever going for a few more amazing years. Two big thumbs up from the Simostronomer.