Stars and Dust through Baade's Window (APOD 19 Dec 2007)

Case · Post by **Case** » Wed Dec 19, 2007 11:04 am

http://antwrp.gsfc.nasa.gov/apod/ap071219.html

The description isn't very clear on what section of the image is designated as Baade's Window. Is it one of these sections drawn in below, or yet another region?

Prospero_at_work · Post by **Prospero_at_work** » Wed Dec 19, 2007 1:59 pm

just to say I found myself puzled by exactly the same point as Case, trying to see if I could spot the window in the picture, and following the links to see if they helped. (They didn't). I'd love to know too!

13 Rabbit · Post by **13 Rabbit** » Wed Dec 19, 2007 3:23 pm

Use the "Search" function at the bottom of APOD. Search for "Baade"

Indigo_Sunrise · Post by **Indigo_Sunrise** » Wed Dec 19, 2007 3:25 pm

I was wondering if the 'window' was actually one of those darker dust areas...? (They sort of remind me of Bok's globules.)
Hopefully someone will be along to clarify.

Prospero_at_work · Post by **Prospero_at_work** » Wed Dec 19, 2007 3:46 pm

Thanks 13 rabbit, but i tried that and am none the wiser! That seems to explain what the window is, tho the science in the paper is a bit opaque for me, it was more to identify the area of the window on the fantastic photo!

Qev · Post by **Qev** » Wed Dec 19, 2007 6:36 pm

This site seems to do a nice job of pointing out where the Window is:

http://migall.fastmail.fm/astronomy/sta ... es_w02.htm

It's apparently about four degrees south of the galactic center in Sagittarius.

DavidLeodis · Post by **DavidLeodis** » Thu Dec 20, 2007 12:09 pm

I am also very confused as to what is Baade's Window in the image. Is it the small dark area just below a bright object in the centre about a quarter of the way in from the right edge? The description with the image in Stephane Guisard's website however only adds to my confusion. This APOD is a good example of when an annotated image would be a great help.

Nice picture though.

geonuc · Post by **geonuc** » Thu Dec 20, 2007 1:15 pm

I must be dense. I'm still not sure where the window is, even after visiting the site Qev linked.

Qev · Post by **Qev** » Thu Dec 20, 2007 7:37 pm

I can't quite figure out what the reference to the "right side" of the image is about in the writeup for that APoD, since unless I'm completely off-base, Baade's Window comprises the area within about half a degree around NGC 6522. It's basically just a low-density region in the gas clouds in the plane of the Milky Way, allowing us to see into the bright, star-packed region very close to the galactic center.

On the other site I linked to in my previous post, bear in mind the images there are rotated 180 degrees from the APoD picture, so 'up' there is 'down' here. I've stuck a version of the APoD image with a couple labels on it to make comparing the two a bit easier, here. Zoom levels 4 and 5 annotated on the other site give the best idea of where it is.

geonuc · Post by **geonuc** » Fri Dec 21, 2007 12:35 pm

Qev wrote:I can't quite figure out what the reference to the "right side" of the image is about in the writeup for that APoD, since unless I'm completely off-base, Baade's Window comprises the area within about half a degree around NGC 6522. It's basically just a low-density region in the gas clouds in the plane of the Milky Way, allowing us to see into the bright, star-packed region very close to the galactic center.

On the other site I linked to in my previous post, bear in mind the images there are rotated 180 degrees from the APoD picture, so 'up' there is 'down' here. I've stuck a version of the APoD image with a couple labels on it to make comparing the two a bit easier, here. Zoom levels 4 and 5 annotated on the other site give the best idea of where it is.

Thanks for the annotated image, Qev. I guess the reason I was (am) a bit confused is that I expect to see 'something' that differentiates the window from the region immediately adjacent and I don't see that.

The only unusual thing I see on the right side of the APOD image is a small, completely dark butterfly shape, but that would be an opaque region, right? In other words, the opposite of a window.

NoelC · Post by **NoelC** » Thu Dec 27, 2007 2:37 pm

I had thought that in general Baade's window was the larger area where the brightest overall light from the stars in the galaxy center is being seen. Essentially the lightest parts in Stephanie's image. However, the more I search the more it appears it's just the region right around NGC 6522.

So now the question is: How did astronomers (e.g.,Walter Baade), differentiate the brightening there as being able to see deep into the galaxy's core vs. the brightening nearby? Or is there a difference?

-Noel

NoelC · Post by **NoelC** » Thu Dec 27, 2007 5:24 pm

I've gone ahead and made a 1 degree square image out of the high resolution data in the STScI Digitized Sky Survey. The red plate was from POSS2 data captured in 1996 through the UK Schmidt telescope, and the blue plate was from POSS1 data captured in 1958 through the Palomar Schmidt telescope. Not too many stars have moved.

One thing I noticed is a slight shift in the color toward blue overall of stars in the general area identified as Baade's Window (and running roughly upper-left to lower-right in this image). Perhaps that's key.

Click on the small image below to see a big image. Warning: Large file.

-Noel

Mushhushshu13 · Post by **Mushhushshu13** » Mon Dec 31, 2007 3:37 pm

Probaby the darker area to the bottom right.

Indigo_Sunrise · Post by **Indigo_Sunrise** » Fri Jan 04, 2008 12:03 pm

From here:

http://astro.umsystem.edu/apml/ARCHIVES ... 00221.html
Hi all,

One of the richest star clouds in the Milkyway is not really an isolated
star cloud, but a window to the Milkyway beyond:
http://www.psiaz.com/schur/astro/filmim ... aade1.html
comments?

Chris Schur
Astrophotograpy site: http://www.PSIAZ.com/schur/astro/index.html

So now I'm gonna guess it's the "star cloud" area in the image, if that makes any more sense...?

NoelC · Post by **NoelC** » Sat Jan 05, 2008 11:20 am

It's definitely an area of star clouds, which describes most of the light areas in the image. The question is which part?

The more I review this the more I believe it to be the small red square Case put up, and which is shown in my closeup.

-Noel

Starship Asterisk*