APOD: Messier 101 (2011 Apr 15)

APOD Robot · Post by **APOD Robot** » Fri Apr 15, 2011 4:06 am

Messier 101

Explanation: Big, beautiful spiral galaxy M101 is one of the last entries in Charles Messier's famous catalog, but definitely not one of the least. About 170,000 light-years across, this galaxy is enormous, almost twice the size of our own Milky Way galaxy. M101 was also one of the original spiral nebulae observed by Lord Rosse's large 19th century telescope, the Leviathan of Parsontown. This mosaic of M101 was assembled from Hubble Legacy Archive data. Additional ground-based data was included to further define the telltale reddish emission from atomic hydrogen gas in this gorgeous galaxy's star forming regions. The sharp image shows stunning features in the galaxy's face-on disk of stars and dust along with background galaxies, some visible right through M101 itself. Also known as the Pinwheel Galaxy, M101 lies within the boundaries of the northern constellation Ursa Major, about 25 million light-years away.

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Ann · Post by **Ann** » Fri Apr 15, 2011 5:04 am

This is a very, very beautiful image of a remarkable galaxy. The Hubble telescope worked its magic to acquire the data, and Robert Gendler used his wonderful skill to process the data and create a stunning image out of it.

Ann

nstahl · Post by **nstahl** » Fri Apr 15, 2011 10:02 am

Great image! And thanks for bringing up the fascinating story of the Leviathan of Parson(s)town. By going to Google Images I was able to find some better pictures than the one in that link.

neufer · Post by **neufer** » Fri Apr 15, 2011 11:16 am

http://asterisk.apod.com/viewtopic.php?f=9&t=23318#p146263 wrote:
Messier 74 ... has the second lowest surface brightness of all the Messier objects.

(M101 has the lowest.)

orin stepanek · Post by **orin stepanek** » Fri Apr 15, 2011 11:48 am

With it's arms spread loosely; it looks like a galaxy interrupted!

emc · Post by **emc** » Fri Apr 15, 2011 1:08 pm

reckon it could have gobbled up other galaxies over time… that might that explain the interrupted look

biddie67 · Post by **biddie67** » Fri Apr 15, 2011 1:22 pm

I was fascinated by the little cluster of stars off the end of the arm towards the lower left of the photo. If there were cognizant life on a planet around one of the stars higher up in the plane of the disk, they might have a wonderful view of their galaxy!

What does the phrase " Hubble Legacy Archive data" refer to?

owlice · Post by **owlice** » Fri Apr 15, 2011 1:27 pm

biddie: http://hla.stsci.edu/

The Hubble Legacy Archive (HLA) is designed to optimize science from the Hubble Space Telescope by providing online, enhanced Hubble products and advanced browsing capabilities. The HLA is a joint project of the Space Telescope Science Institute (STScI), the Space Telescope European Coordinating Facility (ST-ECF), and the Canadian Astronomy Data Centre (CADC).

Anyone can download Hubble data from the archive and play with it.

Psnarf · Post by **Psnarf** » Fri Apr 15, 2011 2:17 pm

I'm intrigued by the dust patterns at the center of the galaxy. Looking head on, those dust lanes would be above the object at the center. Imagining a 3D image, the two lanes on the top of the central globe appear to originate at the top of the sphere and spiral down away from the center. Either that, or the dust spirals remain in the same plane on the top, presenting a bit of a conundrum. (Friction from the rotating central globe?)

neufer · Post by **neufer** » Fri Apr 15, 2011 2:35 pm

Psnarf wrote:
I'm intrigued by the dust patterns at the center of the galaxy. Looking head on, those dust lanes would be above the object at the center. Imagining a 3D image, the two lanes on the top of the central globe appear to originate at the top of the sphere and spiral down away from the center. Either that, or the dust spirals remain in the same plane on the top, presenting a bit of a conundrum. (Friction from the rotating central globe?)

http://www.mpia.de/Public/menu_q2.php?Aktuelles/Bild_des_Monats/old_picture/2005/08-05/08-05_en.html wrote:
Multi-wavelength image of the Spiral Galaxy Messier 101
<<Three color composite image of the nearby spiral galaxy M101. The green color represents emission from neutral hydrogen (HI), emitted at 21 cm. The HI observations are part of VLA The HI Nearby Galaxy Survey (THINGS) which is based at MPIA (image credit: Fabian Walter, MPIA).

Blue shows UV emission due to recent (<10⁸ yr) star formation as seen by the Galaxy Evolution Explorer (GALEX).

Red indicates warm dust emission as traced by infrared emission at 24 microns as seen by SPITZER (image credit: Karl Gordon, Steward Observatory).>>

Multiwavelength Astronomy

Starswarm Magellan · Post by **Starswarm Magellan** » Fri Apr 15, 2011 8:24 pm

M101 may be the model for an object in the center of the "Starry Night" painting by van. His friends call him van.

biddie67 · Post by **biddie67** » Fri Apr 15, 2011 9:51 pm

Thanks, Owlice!!

owlice · Post by **owlice** » Fri Apr 15, 2011 10:20 pm

You're welcome, biddie!

How's the bicycling coming along? Been riding?

Jerry1 · Post by **Jerry1** » Fri Apr 15, 2011 10:33 pm

I remember pointing my Criterion RV6 telescope at this object on a cold Colorado night in the early 80's and not being able to see a thing. I kept going back and checking the charts and repositioning my telescope. About this time I was thinking to myself, "It's supposed to be right there, dammit!" Suddenly, it dawned on me that something very dim was completely filling the field of view of my 25mm eyepiece.

Mactavish · Post by **Mactavish** » Sat Apr 16, 2011 4:14 am

Typical of Gendler's work. Absolutely magnificent!

biddie67 · Post by **biddie67** » Sat Apr 16, 2011 6:02 am

Owlice - unfortunately, no. Been recovering from a knee injury ....

Ann · Post by **Ann** » Sat Apr 16, 2011 6:49 am

This sort of galaxy is what you get if you have only a small central population of old stars and an incredibly widespread, intrinsically bright but widely scattered population of young stars. The galaxy goes on and on, but it just doesn't get very bright anywhere!

Ann

owlice · Post by **owlice** » Sat Apr 16, 2011 11:32 am

Ouch, biddie; sorry to read that. I wish you a speedy recovery!

Starship Asterisk*

APOD: Messier 101 (2011 Apr 15)

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