PDA

View Full Version : Two of the Milky Way's Spiral Arms Go Missing



01101001
2008-Jun-03, 05:55 PM
Heard at the live AAS press conference (in progress here (http://www.ustream.tv/channel/astronomy-cast-live-%3A-press-conference-coverage), availability announced here (http://www.badastronomy.com/bablog/2008/06/03/tuesday-aas-presscon-2-the-milky-way/)):

At Spitzer/Caltech: Two of the Milky Way's Spiral Arms Go Missing (http://www.spitzer.caltech.edu/Media/releases/ssc2008-10/release.shtml) see the latest portrait of our galaxy.


For decades, astronomers have been blind to what our galaxy, the Milky Way, really looks like. After all, we sit in the midst of it and can't step outside for a bird's eye view.

Now, new images from NASA's Spitzer Space Telescope are shedding light on the true structure of the Milky Way, revealing that it has just two major arms of stars instead of the four it was previously thought to possess.

http://www.spitzer.caltech.edu/Media/releases/ssc2008-10/images/ssc2008-10a1_200.jpg (http://www.spitzer.caltech.edu/Media/releases/ssc2008-10/release.shtml)

Bigger Pictures (one annotated with sun's location and our vantage point's major visible features) (http://www.spitzer.caltech.edu/Media/releases/ssc2008-10/visuals.shtml)

Yesteryear's version:

8024

Edit: 17 past the hour. Press conference over.

Edit: Additional source for same stuff: NASA Spitzer Mission :: Multimedia: Our Milky Way Gets a Makeover (http://www.nasa.gov/mission_pages/spitzer/multimedia/20080603a.html)

weatherc
2008-Jun-03, 06:10 PM
Uh-oh.

EVERYBODY PANIC! The Milky Way Galaxy is disappearing! First, we lost half of the Galaxy's mass. (http://www.bautforum.com/astronomy/74730-milky-way-slimmer.html) Now, we're losing entire spiral arms!! By the end of 2012, our Galaxy will be gone! The Mayans knew it all along!

Sorry, I went into woo-woo mode for a second there. Actually, it's pretty interesting to think we're living in a barred spiral galaxy.

redshifter
2008-Jun-03, 06:15 PM
I knew those Masons were up to something...

01101001
2008-Jun-03, 06:19 PM
Actually, it's pretty interesting to think we're living in a barred spiral galaxy.

And someone in the chat room asked about how MW fits in and one presenter declared us a pretty normal barred spiral galaxy. Whew.

(I just think it's so cool to be able to ask such questions at an astronomy-discovery press conference.)

Swift
2008-Jun-03, 06:21 PM
Uh-oh.

EVERYBODY PANIC! The Milky Way Galaxy is disappearing! First, we lost half of the Galaxy's mass. (http://www.bautforum.com/astronomy/74730-milky-way-slimmer.html) Now, we're losing entire spiral arms!! By the end of 2012, our Galaxy will be gone! The Mayans knew it all along!

Don't worry, galaxies, like starfish, can grow their arms back. :whistle:

Iron Sun 254
2008-Jun-03, 06:44 PM
They didn't disappear. They just got downgraded to minor arms. At least Pluto won't feel lonely any more.

01101001
2008-Jun-03, 06:48 PM
They didn't disappear. They just got downgraded to minor arms. At least Pluto won't feel lonely any more.

Does Orion's Arm (Wikipedia (http://en.wikipedia.org/wiki/Orion's_Arm)) have to change its name to Orion's Spur?

Iron Sun 254
2008-Jun-03, 07:07 PM
Does Orion's Arm have to change its name to Orion's Spur?

I believe the new name will be "The Orion Suburb."

Tacitus
2008-Jun-03, 08:59 PM
Does that mean that the Milky Way can now be reclassified as "Mostly Armless?"

(yeah, I just used the same line over on the UT site, but why waste a good good one-liner, I say!)

Kaptain K
2008-Jun-04, 12:23 AM
Does that mean that the Milky Way can now be reclassified as "Mostly Armless?"

OUCH!

RalofTyr
2008-Jun-04, 05:05 AM
The Andromadeans will think we are easy prey. After all, we are unarmed.

parallaxicality
2008-Jun-04, 10:16 AM
I think our galaxy looks nicer now. Much more elegant and feminine.

AndreasJ
2008-Jun-04, 11:55 AM
I think our galaxy looks nicer now. Much more elegant and feminine.

Losing a trillion solar masses would do wonders for anyone's figure.

eburacum45
2008-Jun-05, 05:45 AM
Does Orion's Arm (Wikipedia (http://en.wikipedia.org/wiki/Orion's_Arm)) have to change its name to Orion's Spur?
Orion's Spur? I think not.

Sir Real
2008-Jun-06, 07:43 PM
Orion's Spur? I think not.

That's funny (odd funny, not 'haha' funny). I've been using the Orion Spur as part of my address for a number of years now...

Latitude: 34 xx' xx" N
Longitude: 117 xx' xx" W
Planet: Terra (Earth)
Star: Sol
Arm: Orion Spur
Galaxy: Milky Way
Verse: Uni

eburacum45
2008-Jun-07, 10:48 AM
Note that this survey does not actually affect the significance of the Orion Arm, or Spur, directly; it is mainly concerned with the status of the Sagittarus and Norma Arms, which have both been relegated to minor arm status. The Orion Arm (or Spur) was already a minor arm, so its status is unchanged.

Discussions at Celestia so far have gone against changing the representation of the galaxy in that program yet, as the shapes of the spiral arms in the model are based on the COBE and 2MASS surveys, which don't seem to suggest that the Sagittarius and Norma arms should, in fact, be relegated. Yet.

parallaxicality
2008-Jun-07, 10:52 AM
You just wait. Soon people will be clamoring about their demotion, claiming that the vote wasn't representative, and that they will still refer to them as fully fledged arms regardless of what any pompous astronomers think.

Jerry
2008-Jun-08, 02:37 AM
First Pluto is demoted, then the galaxy. Next thing we know, the entire universe will be relegated to some locker in a train station.

Acolyte
2008-Jun-08, 04:06 AM
Don't worry, galaxies, like starfish, can grow their arms back. :whistle:I wish you were right but I think we're barred!

geonuc
2008-Jun-09, 09:24 AM
I don't know if the Spitzer site has it, but APOD published an annotated version of the image:

http://antwrp.gsfc.nasa.gov/apod/ap080606.html

It seems that one of the minor arms - the 'Outer Arm' - is the longest, although it's broken up in places. Very cool stuff.