Blogs / Bad Astronomy

I’ve been getting email and tweets about the American Astronomical Society meeting going on right now in Long Beach California, so I thought I’d make a coupla quick comments:

1) I am not there. Long story, but it just didn’t work out this year. I love going to the meetings — and I’ll be honest here — because it’s my annual chance to get together with a lot of friends, both new and old. I can’t believe I’ll miss the clubbing night this year… but anyway, I’m not there, and I’m doing any writing about it from home. I’ll preface each post title with "AAS #XX" to let you know it’s from the meeting.

2) You can participate vicariously in the press conferences by going to the Astronomy Cast live stream. Whenever there is a press conference (three times a day, usually) or some other live event, you can watch it there. They have a live chat room on that page as well, so you can actually participate!

That’s it. I’ll post what I can about the meeting, as well as the usual nonsense. But expect to hear a lot of astronomy news this week! And remember, those yellow Digg buttons at the tops of my posts work pretty well.

I’ll be on TV tonight and all this week: The History Channel is airing a show called "Seven Signs of the Apocalypse" at 21:00 Eastern (US) time (but check your local listings). I did what I call a "stand-up interview" for this show: me standing in front of some interesting background while I talk astronomy. In this case, it was asteroid impacts and gamma-ray bursts, two of my fave death-from-the-skies scenarios.

I’ve seen some of the graphics from the show, and they are spectacular. It should be pretty cool, even if couched in an "End Times" framework.

Astronomers using the Hubble and Spitzer Space Telescopes have just released an incredible image of the center of the Milky Way:

Hubble and Spitzer map of Milky Way Center. Credit: NASA, ESA, and Q.D. Wang (University of Massachusetts, Amherst), Jet Propulsion Laboratory, and S. Stolovy (Spitzer Science Center/Caltech)

Wow. Click to get access to much higher-res versions that will embiggen your brain. They have HUGE versions too.

The image is in the infrared, showing piles of warm gas and dust that litter the galactic center. The weird structures are carved out by massive star winds, supernova explosions, bursts of star formation, and more. Lurking in this image, far too small to be seen, is the supermassive black hole at the heart of our galaxy. Even though our past and future are intertwined — the black hole formed around the same time the galaxy did, and evidence is that they helped shape each other — the black hole is invisible. It’s smaller than our solar system, and this map is millions of times wider (300 x 115 light years); the black hole is far smaller than a pixel on this scale.

To get an idea of the scale of this image, here’s a closeup on the lower left portion:

There’s so much to see! The fingers of stalagmite-looking gas on the left are actually columns of gas light years long being eroded by the winds of massive stars, probably that bright cluster to the right of the fingers. On the right is a bright star surrounded by a halo of gas. What’s that? I’m not sure; it’s probably another just-born massive star carving out a bubble of gas around it. That bubble is several light years across!

And just look at the sheer number of stars in the image! It’s hard to grasp just how big a number 200 billion is, but that’s how many stars are in the galaxy. There are countless thousands in this one image, and it represents a tiny, tiny fraction of our galaxy.

Wow.

1) Black holes succor!

So we live in a spiral galaxy, right? That means it’s a flat disk, with spiral arms, a bulge of stars in the middle, and right at the center sits a black hole — all big galaxies appear to have one. The monster in our middle tips the cosmic scales at over 4 million times the mass of the Sun. That sounds like a lot, but remember there are about 200 billion stars in the Milky Way, so in reality the black hole is 0.002% of the mass of the galaxy, more or less.

Artist’s concept of young stars near the galactic center. Credit: NASA, ESA, and A. Schaller (for STScI)

Near the black hole, you’d think the environment is not exactly nurturing. The gravity of the hole is enormous, of course. Stars can orbit it in stable paths that last for billions of years, but big objects like gas clouds can be shredded; the black hole pulls on one side more strongly than the other, which can tear the clouds apart.

So we don’t expect to see young stars near the very center of the Milky Way — yet that is precisely what astronomers have found using the radio telescopes in the Very Large Array in New Mexico!

Young stars being born cry out in radio wavelengths, and the VLA is exceptional at precisely pinpointing post-partum protostars. The astronomers found two such young stars still in the act of forming. Incredibly, this means their cocoon of gas must survive being so close to the black hole — in this case, just seven and ten light years away! Since most gas clouds are light years across, this means these clouds must be smaller and more dense than usual.

This study means that stars can form in relatively hostile environments, and that in turn tells more about how stars form, which is cool, and what things are like very close to the maw of the supermassive black hole lurking at the galactic center, which is very cool indeed.

2) Our Galaxy is beefier than thought

Sitting as we do off to one side of the Milky Way, it’s really hard to get a good census of it. Dust clouds block our view, for example, and the Sun is rushing around the center of the galaxy along with the hundreds of billions of others.

Map of the galaxy, showing the center, the arms, and the locations of the gas clouds used to get the data. Our location is the red dot. Credit: Robert Hurt, IPAC; Mark Reid, CfA, NRAO/AUI/NSF

However, astronomers have used a collection of radio telescopes strung across the Earth to get better data than ever before on our home galaxy. And what they found is pretty interesting: we thought the Sun was going around the center at about 220 km/sec, but it turns out we’re actually moving at closer to 270 km/sec!

The speed of the Sun depends on the combined mass of all the stars, gas, and dust between us and the center. The gravity of all that stuff is what determines our speed. If we’re moving faster than we thought, then the galaxy itself must be more massive. This increase in speed indicates the Milky Way is actually 50% more massive than we previously thought!

That’s a big difference. That means we’re the equal of the Andromeda Galaxy, which we thought was the big boy of the local collection of galaxies. Now we don’t have to hang our head in shame any more.

Even cooler, the astronomers discovered the Milky Way appears to have four spiral arms, and not just two!

So we’re as massive as Andromeda, and we have four arms. Hmmmm. The obvious conclusion: we can easily take Andromeda on and beat it up! In a couple of billion years, we’ll get our chance, when the two galaxies collide and eventually merge. Sadly, after that, we’ll most likely be an elliptical puffball galaxy, with no arms at all. But until then, it looks like we’re king of the hill.

Richard and me in front of an Alaskan glacier

Heh. Everybody waits until the new year to put up their ‘casts. I have three more now: one rather short, one longer, and one that’s Greek to me.

1) My friend and Aussie skeptic Richard Saunders asked me for a 30 second blurb for whatever I wanted, so I sent him a rapid-fire rundown of the blogs I write for. That’s up at SkepticZone.tv, with my blurb at about 25:30 (here’s a direct link to the MP3). SkepticZone is the #1 podcast in Australian iTunes for social sciences, and is doing very well globally for skeptical and scientific podcasts too.

2) I was interviewed by John Hockenberry (I remember him from MSNBC many years ago!) who does a radio show called The Takeaway. We talked about Obama’s mixed signals for NASA (they contacted me after reading what I wrote on the subject). That was a fun interview; I had to drive to a local radio station to use their ISDN line, so it felt more official. Check out the cool media player they have on their site! Very cute. My part starts at 1:03:50.

3) I was interviewed about the book by Katerina Economakou for the Greek newspaper Eleftherotypia. The piece is online, but — in the "duh" category — it’s in Greek. The cool thing is that apparently my name is spelled Φίλιπ Πλέιτ in Greek. κοολ!

This week is the meeting of the American Astronomical Society, where lots of cool news is released. I am not attending, but I’ll be reporting on some of the news released during the event. You can watch the press conferences live at the AstronomyCast live stream.

This morning we have two interesting results coming from the orbiting infrared observatory Spitzer Space Telescope.

1) Baby Jupiters kicked out of the crib early

Spitzer observations show that planets have to form quickly, before they run out of food.

Stars form from clouds of gas and dust, which collapse into disks (called protoplanetary disks). The star forms in the center of the disk, and planets form farther out. We have a gazillion examples of this; I worked on Hubble observing quite a few such systems. A big question in this field is, how long does it take for the planets to form? Eventually, the star’s winds blow away the gas disk, and at that point the big gas giant planets are done; there’s no more material for them to eat allowing them to grow. It’s a bit like trying to get a building put together on a construction site before the foreman blows the whistle and tells you to go home.

Spitzer view of the young cluster NGC 2362; click to embiggen.

Now we have an idea! Astronomers took a look at the young star cluster NGC 2362, known through previous observations to be about 5 million years old. What they found is pretty cool: stars with a mass of about the Sun’s or higher don’t have their big protoplanetary disks anymore, and only a few with less mass still have those disks.

Assuming the Sun and most stars form under similar conditions, this puts an upper limit on how quickly gas giant planets like Jupiter and Saturn planets can form: 5 million years. If they took longer, they’d never make it before the raw building materials were blown away.

I have to say, that’s pretty fast! Objects like Jupiter are pretty beefy, and having it collect all that material in 5 million years (or less!) means it grows rapidly. The rate at which materials collect must heat those planets unimaginably hot!

Interestingly, the astronomers found that while the bulk of the gas disk gets blown away after 5 million years, there is still evidence of rocky material existing, which means that there is still some leftover bricks with which to build planets. These would probably help planets like Earth form, so it looks like gas giants form most of their bulk early, and while they can still grow some using that rocky material, that’s not a big deal compared to the early growth. But Earth-like planets need not be so rushed; there is still plenty of material left over to form them.

So Jupiter may be more than Earth’s big brother due to its size; it may actually have formed first, too! Just so you know, it has 300 times the Earth’s mass, so it must have grown incredibly quickly. And now that it’s so big, I’m glad it doesn’t give us cosmic wedgies or anything like that. As big brothers go, Jupiter’s pretty cool.

2) Astronomers using Spitzer Space Telescope have found that dead stars eat their kids.

Stars like the Sun eventually run out of fuel. When they do, they expand into red giants and shed their outer layers. After a few hundred million years all that’s left is the exposed core of the star, compressed into an object called a white dwarf; a ball the size of the Earth with the mass of a star.

If the star had planets, it may have eaten the inner ones (like Mercury and Venus) during the red giant phase. But even long after the star is dead, it still feeds on the living: astronomers have detected white dwarfs consuming asteroids. Any of these rocky denizens that survived their star’s death paroxysms may yet have a fiery fate. Gravitational interactions with other asteroids or any surviving planets can send the rock down to the star, where the ferocious gravity tears the asteroid apart, grinding it into dust. This dust can be detected in infrared spectra of the star.

Spitzer provides that sort of data, and astronomers have found eight such examples: white dwarfs that have clearly been feasting on asteroids. Two had been known previously, but this new result indicates that this event is common. It also shows that many stars have asteroid belts, itself an important result! Also, the asteroids orbiting these stars appear to be low in carbon, which is similar to the asteroids in our own solar system. That means that events leading to the formation of the Earth and other planets is likely common throughout space… something that indicates there may be more Earths out there.

So both Spitzer results show us that planets like Earth may be out there, forming commonly around Sun-like stars! Every day, we get a little bit closer to finding another blue-green planet like our own.

I stumbled on a fascinating video. It’s an evolutionary allegory told in modern methods with a focus on the gestalt…

… oh, who am I kidding? It has a freakin’ STEAMPUNK T-REX! Hawesommmmme! I suggest you go to the YouTube page itself and click the "Watch in HD" link under the video to the right. This deserves good resolution.

That was totally cool. Man, I love that kind of animation.

The video is actually a commercial in German, of course. I don’t know what "Wir hassen teuer" means, because it sounds colloquial to me. Haben wir BABloggees wer Deutsches sprechen? I think I got that right. Well, you’ll let me know.

Tip o’ the mechanical goggles to Fark.