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APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:06 am
by APOD Robot
At the Core of NGC 6752
Explanation: This sharp Hubble Space Telescope view looks
deep into NGC 6752. Some 13,000 light-years away toward the southern constellation Pavo, the globular star cluster
roams the halo of our Milky Way galaxy. Over 10 billion years old,
NGC 6752 holds over 100 thousand
stars in a sphere about 100 light-years in diameter, but the Hubble image frame spans the central 10 or so light-years and resolves stars near the
dense cluster core. In fact the frame includes some of the cluster's
blue straggler stars, stars which appear to be too young and massive to exist in a cluster whose stars are all expected to be at least twice as old as the Sun.
Explorations of the NGC 6752 have also indicated that a remarkable fraction of the stars near the cluster's core, are multiple star systems, supporting
arguments that star mergers and collisions in the dense stellar environment can create the cluster's
blue straggler stars.
[/b]
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 6:04 am
by Boomer12k
Oooooh! Sparkly!!!
:---[===] *
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 6:11 am
by Ann
It is a sharp picture, as we expect from Hubble. No blue filter has been used, as I half-expect from ESA. The filters used were infrared, yellow-orange and yellow-green, which shouldn't be optimal if you are looking for blue stars. Of course, it could well be that many of the blue straggler stars aren't blue, but peak in the yellow-green part of the spectrum, where you would have expected them to peak in the yellow-orange part instead. Besides, it is equally possible that the search for blue stragglers wasn't a top priority here, but that the main purpose was to resolve as many little red dwarfs as possible.
Ann
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 7:30 am
by Sandstone
Ann wrote:The filters used were infrared, yellow-orange and yellow-green
Ann, how can you tell what filters were used? Just curious & wanting to learn.
Mark
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 7:32 am
by bystander
Young Stars at Home in an Ancient Cluster (NGC 6752)
ESA/HEIC Hubble Picture of the Week (2012 Jan 30)
http://www.spacetelescope.org/images/potw1205a/
NASA Goddard Photos and Videos on Flickr (2012 Feb 08)
http://www.flickr.com/photos/gsfc/6841443637/
http://asterisk.apod.com/viewtopic.php?f=29&t=26950
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 10:30 am
by Baldwin504
If one could look into the maw of a worm hole, what would it look like?
Could it possibly look like NGC 6752?
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 11:05 am
by Ann
Sandstone wrote:Ann wrote:The filters used were infrared, yellow-orange and yellow-green
Ann, how can you tell what filters were used? Just curious & wanting to learn.
Mark
Each APOD usually contains a link called "This image" or something like that. This time there was no such link, so I tried the first link,
deep into NGC 6752. That link takes you to the Hubble/ESA page where you can read about this particular image. This page also gives you facts about how, when and with what telescope the image was taken. You can see (look at the right side of the page), that three filters were used, an infrared filter centered at 814 nm, a optical filter centered at 606 nm, and another optical filter centered at 555 nm.
To me it is important to realize that 606 nm is a yellow-orange color, since 580 nm represents a very pure yellow, and longer waves means redder colors. Therefore 606 nm is a redder color than 580 nm, which is a pure yellow color. 555 nm is a yellowish green color, more like grass than traffic light green.
The picture that was taken through an infrared filter was shown as red. That is why the word
infrared is shown as red on the Hubble/ESA page. The
606 nm optical filter is shown as green, meaning that the picture that was taken through the yellow-orange filter (and which detected yellow-orange light) is shown as a green image. The
555 nm optical picture is shown as blue, meaning that the picture that was taken through the yellow-green filter (and which detected yellow-green light) is shown as a blue image.
An interesting consequence of the choice of filters is that there will be very small color differences between the stars in the image. All stars in a globular cluster (except, perhaps, some young white dwarfs and some hot horizontal branch stars) can be expected to emit quite a lot of yellow-green light and quite a lot of yellow-orange light, too. Not all stars can reasonably be expected to emit a lot of infrared light, but only those stars whose spectra peak far into the infrared can be expected to emit so much more infrared than visual light that they look reddish at all through the filters that were used for this image. Also, only the stars that are considerably hotter than the Sun can be expected to to look at all bluish. All other stars can be expected to emit so much infrared, yellow-orange and yellow-green light that their apparent color will be more or less white in an image like this one.
If one of the filters had been a
blue one, centered at, say, 450 nm, then most reddish stars in this globular cluster would have looked much redder than they do in this image. Most reddish stars emit a reasonable amount of yellow-green light, but they don't emit a lot of blue light at all. Therefore these red stars would only have been detected by the middle (yellow-green or yellow-orange) filter and the long-wave (red or infrared) filter. Similarly, the truly hot stars would have stood out better than they do in this image, because they would have been strongly detected by the blue filter and therefore they would have looked very noticeably bluer than the other stars in this cluster.
Ann
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 1:01 pm
by Fossilman
As a longtime viewer of APOD I sometimes see things in the images that look weird or non-random. Looking at today's image, I see strings of stars throughout the cluster. Has anyone ever commented on this or am I just having a post-60's flashback ?
Best to all, M
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 1:37 pm
by KEVINDWYER
Yes I was ging to ask the same question as Fossilman. In this photo as in many other photos of starfields there seen to be too many short strings of stars than I would expect to see in a random distribution. Is something going on here apart from my uninformed ideas about randomness?
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 1:43 pm
by orin stepanek
There appears to be a lot of blue stars in this cluster! Maybe it's more the norm than not.
![Confused :?](./images/smilies/icon_confused.gif)
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 1:53 pm
by neufer
.
http://en.wikipedia.org/wiki/Connect_the_dots wrote:
<<Connect the dots, also known as dot to dot or join the dots is a form of puzzle containing a sequence of numbered dots. When a line is drawn connecting the dots the outline of an object is revealed. The puzzles often contain simple line art to enhance the image created or to assist in rendering a complex section of the image. Connect the dots puzzles are generally created for children. The use of numbers can be replaced with letters or other symbols.
In adult discourse the phrase "connect the dots" can be used as a metaphor to illustrate an ability (or inability) to associate one idea with another, to find the "big picture", or salient feature, in a mass of data.
Reuven Feuerstein features the connection of dots as the first tool in his cognitive development program.>>
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 2:54 pm
by jshirey
100 thousand stars within 100 light years. Here, near Sol, it is the only star within 4.6 light years. There are 1,000 stars/1 light year there and 1 star/9 light years here.....9,000 times more stars in that region of space than ours! I wonder what the night sky would look like there......
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 3:13 pm
by Chris Peterson
Baldwin504 wrote:If one could look into the maw of a worm hole, what would it look like?
Could it possibly look like NGC 6752?
No. I've prepared a highly accurate rendering of the view directly into a black hole:
![blackhole.jpg](./download/file.php?id=6257&sid=a2da28cf52b8d75eb4c9e36150182b7d)
- blackhole.jpg (3.52 KiB) Viewed 7664 times
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 3:23 pm
by Guest
What would the night sky look like from inside that cluster????
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 3:39 pm
by NoelC
Guest wrote:What would the night sky look like from inside that cluster????
I'm reminded of an old classic Asimov short story, "Nightfall" I think it was, where people evolved in a world where there is always light, and they all go mad from fear of the dark when they get an ever-so-rare simultaneous eclipse of all the suns lighting their planet.
-Noel
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:22 pm
by Flibberty Giblets
jshirey wrote:100 thousand stars within 100 light years. Here, near Sol, it is the only star within 4.6 light years. There are 1,000 stars/1 light year there and 1 star/9 light years here.....9,000 times more stars in that region of space than ours!
At the "
dense cluster core" link
http://heritage.stsci.edu/2003/21/caption.html in the image caption it says "Here, the stars are jam-packed together. The stellar density is about a million times greater than in our Sun's stellar neighborhood. The stars are only a few light-weeks apart, while the nearest star to our Sun is over four light-years away."
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:26 pm
by Beyond
Chris Peterson wrote:Baldwin504 wrote:If one could look into the maw of a worm hole, what would it look like?
Could it possibly look like NGC 6752?
No. I've prepared a highly accurate rendering of the view directly into a black hole:
blackhole.jpg
Highly accurate rendering
![Question :?:](./images/smilies/icon_question.gif)
Gee, i always thought of black holes as being kinda roundish. Oh well.
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:34 pm
by Chris Peterson
Beyond wrote:Highly accurate rendering :?: Gee, i always thought of black holes as being kinda roundish. Oh well.
Not when you're "look[ing] into the maw" of one! <g>
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:40 pm
by Ann
Beyond wrote:
Highly accurate rendering
![Question :?:](./images/smilies/icon_question.gif)
Gee, i always thought of black holes as being kinda roundish. Oh well.
Black hole here
Ann
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:46 pm
by Beyond
Chris Peterson wrote:Beyond wrote:Highly accurate rendering
![Question :?:](./images/smilies/icon_question.gif)
Gee, i always thought of black holes as being kinda roundish. Oh well.
Not when you're "look[ing] into the maw" of one! <g>
Gads! I forgot the 'open sesame' part. So when you see them kinda roundish, you're pretty well safe. When you see them rather squarish, you're about to be recycled.
ha-ha, i clicked the submit button and a picture of a horse popped up in my face and i said what the.... then i realized that Ann beat me to the posting line by a nose
![Exclamation :!:](./images/smilies/icon_exclaim.gif)
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 5:50 pm
by Chris Peterson
Ann wrote:Beyond wrote:
Highly accurate rendering :?: Gee, i always thought of black holes as being kinda roundish. Oh well.
Black hole here :?: :arrow:
Ann
Well, that's one of them...
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 7:49 pm
by Donnageddon
What struck me in the description is that NGC 6752 is "Over 10 billion years old". That got me to asking "How old is the Milky Way?"
Wikipedia informs it is 13.2 billion years old.
http://en.wikipedia.org/wiki/Milky_Way
I am so used to seeing fuzzy red blobs in deep space images of galaxies that formed not long after the Big Bang, that I never thought our own galaxy was formed
only ~500 million after the creation of the universe.
But then if there are any astronomers on those far away galaxies looking at the Milky Way, they are going to see MW as it was long ago, and wonder at how old our galaxy is.
Its all relative.
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 7:51 pm
by Donnageddon
Chris Peterson wrote:Ann wrote:Beyond wrote:
Highly accurate rendering
![Question :?:](./images/smilies/icon_question.gif)
Gee, i always thought of black holes as being kinda roundish. Oh well.
Black hole here
Ann
Well, that's one of them...
Yes, when I think of a horse's black hole (which is not too often) I usually think of the other end.
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 8:06 pm
by Chris Peterson
Donnageddon wrote:I am so used to seeing fuzzy red blobs in deep space images of galaxies that formed not long after the Big Bang, that I never thought our own galaxy was formed only ~500 million after the creation of the universe.
Probably, all galaxies formed in the first billion years or so of the Universe- although they continued to evolve long after that (and continue to do so now).
Re: APOD: At the Core of NGC 6752 (2012 Feb 10)
Posted: Fri Feb 10, 2012 8:14 pm
by bystander
Donnageddon wrote:Yes, when I think of a horse's black hole (which is not too often) I usually think of the other end.
If there is stuff coming out of it, wouldn't that be a
white hole?
And wouldn't a
wormhole be a bridge between a black hole (entrance) and a white hole (exit)?