Found images: 2016 October

[starsurfer]

NGC 1316-7
http://www.pbase.com/tango33/image/162738449
Copyright: Kfir Simon

[Ann]

The Toucan and the Cluster (NGC 299)
ESA Hubble Picture of the Week | 2016 Oct 17

[b][i]Credit: ESA/Hubble & NASA[/i][/b]

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[hr][/hr]

It may be famous for hosting spectacular sights such as the Tucana Dwarf Galaxy and 47 Tucanae (heic1510), the second brightest globular cluster in the night sky, but the southern constellation of Tucana (The Toucan) also possesses a variety of unsung cosmic beauties.

One such beauty is NGC 299, an open star cluster located within the Small Magellanic Cloud just under 200 000 light-years away. Open clusters such as this are collections of stars weakly bound by the shackles of gravity, all of which formed from the same massive molecular cloud of gas and dust. Because of this, all the stars have the same age and composition, but vary in their mass because they formed at different positions within the cloud.

This unique property not only ensures a spectacular sight when viewed through a sophisticated instrument attached to a telescope such as Hubble’s Advanced Camera for Surveys, but gives astronomers a cosmic laboratory in which to study the formation and evolution of stars — a process that is thought to depend strongly on a star’s mass.

I, too, love this image.

It's very tempting trying to date the cluster's age just from the appearance of it. Three red giants - make that supergiants - are very prominent, but there are many smaller hot blue stars in the cluster, too.

The fact that the cluster is very rich means that it is massive. It also means that its most massive stars boast a lot of heft. And that means that these heavyweights will turn into red supergiants in just a few million years.

Click to view full size image

The Double cluster in Perseus. Photo: Roth Ritter(?).

A slightly weird thing about NGC 299 is that its brightest red giants look so much brighter than the brightest blue stars. That is unusual. Compare NGC 299 with the Double Cluster in Perseus. Like NGC 299, the two components of the Double Cluster, NGC 869 and NGC 884, are rich, massive and young. There are also bright red supergiants found among the young blue stars. But although the red supergiants are very bright, they don't look obviously brighter than the brightest blue-white and yellow-white stars.

The reason why the red giants of NGC 299 look so bright is probably a consequence of the filters used for the image, 555 nm (yellow-green) and 814 nm (infrared). Red giants will look bright through both filters, whereas blue stars will look very faint through the 814 nm filter, and not look their best through the 555 nm filter. I'd say that the filters used enhance the red stars and suppress the blue ones.

Nevertheless, I think that NGC 299 is sufficiently similar in appearance to the Double Cluster in Perseus that we might guess that NGC 299 is relatively similar in age to the Double Cluster, ~10-15 million years or so. Maybe NGC 299 is even a little older than the brilliant clusters of Perseus. It does look less massive than NGC 869 and 884, suggesting that its most massive stars are also less massive than the heavyweights of the Double Cluster. Therefore these red giants may also be older and fainter than the sparkling citrines of Perseus.

Ann

[bystander]

Youthful NGC 362
ESA Hubble Picture of the Week | 2016 Oct 24

[c][attachment=0]potw1643a[1].jpg[/attachment][/b][/c][hr][/hr]

Globular clusters offer some of the most spectacular sights in the night sky. These ornate spheres contain hundreds of thousands of stars, and reside in the outskirts of galaxies. The Milky Way contains over 150 such clusters — and the one shown in this NASA/ESA Hubble Space Telescope image, named NGC 362, is one of the more unusual ones.

As stars make their way through life they fuse elements together in their cores, creating heavier and heavier elements — known in astronomy as metals — in the process. When these stars die, they flood their surroundings with the material they have formed during their lifetimes, enriching the interstellar medium with metals. Stars that form later therefore contain higher proportions of metals than their older relatives.

By studying the different elements present within individual stars in NGC 362, astronomers discovered that the cluster boasts a surprisingly high metal content, indicating that it is younger than expected. Although most globular clusters are much older than the majority of stars in their host galaxy, NGC 362 bucks the trend, with an age lying between 10 and 11 billion years old. For reference, the age of the Milky Way is estimated to be above 13 billion years.

This image, in which you can view NGC 362’s individual stars, was taken by Hubble’s Advanced Camera for Surveys (ACS).

[Ann]

Youthful NGC 362
ESA Hubble Picture of the Week | 2016 Oct 24

[c]potw1643a[1].jpg[/c][hr][/hr]

Globular clusters offer some of the most spectacular sights in the night sky. These ornate spheres contain hundreds of thousands of stars, and reside in the outskirts of galaxies. The Milky Way contains over 150 such clusters — and the one shown in this NASA/ESA Hubble Space Telescope image, named NGC 362, is one of the more unusual ones.

As stars make their way through life they fuse elements together in their cores, creating heavier and heavier elements — known in astronomy as metals — in the process. When these stars die, they flood their surroundings with the material they have formed during their lifetimes, enriching the interstellar medium with metals. Stars that form later therefore contain higher proportions of metals than their older relatives.

By studying the different elements present within individual stars in NGC 362, astronomers discovered that the cluster boasts a surprisingly high metal content, indicating that it is younger than expected. Although most globular clusters are much older than the majority of stars in their host galaxy, NGC 362 bucks the trend, with an age lying between 10 and 11 billion years old. For reference, the age of the Milky Way is estimated to be above 13 billion years.

This image, in which you can view NGC 362’s individual stars, was taken by Hubble’s Advanced Camera for Surveys (ACS).

Interestingly, for such a comparatively metal-rich cluster, NGC 362 does contain blue horizontal branch stars. Such stars are an indicator of of an extremely metal-poor composition of the globular that they belong to.

M13. Photo: Hubble.

147 Tuc. Photo: Hubble.

However, while blue horizontal stars are undoubtedly present in NGC 263, they appear to be comparatively rare. In the typically metal-poor cluster M13, the blue stars are really numerous, as even this low-resolution version of Hubble's great image at left demonstrates. 147 Tuc, by contrast, is metal-rich and devoid of blue horizontal stars.

NGC 362 may be richer in metals than M13 but poorer in them than 147 Tuc. If NGC 362 is indeed "intermediate", then perhaps it is harder than in M13, but not impossible like in 147 Tuc, for stars to evolve into blue horizontal stars.

Alternatively, perhaps the stars evolve into BHS in NGC 362 as well as in M13, but perhaps they spend less time on the blue horizontal branch the more metal-rich they are.

Ann

[starsurfer]

RCW 16
http://cosmicphotos.com/gallery/image.p ... lbum_id=11
Copyright: Jason Jennings

This nebula is also catalogued as Sh2-311 and NGC 2467.

[starsurfer]

NGC 3521
http://www.billionsandbillions.com/ngc_3521.html
Copyright: Warren Keller/SSRO

Click to view full size image

[starsurfer]

Rosette Nebula (NGC 2237-9)
http://www.tvdavisastropics.com/astroim ... 00003a.htm
Copyright: Thomas Davis

[starsurfer]

NGC 5363-4
http://www.distant-lights.at/ngc5363-2016_05_07.htm
Copyright: Thomas Henne

Click to view full size image

[starsurfer]

NGC 4214
https://www.noao.edu/image_gallery/html/im1280.html
Copyright: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF

[starsurfer]

Fg 1
http://www.pbase.com/strongmanmike2002/fleming_1
Copyright: Michael Sidonio

[starsurfer]

NGC 55
http://www.atacama-photographic-observa ... .php?id=53
Copyright: Thierry Demange, Richard Galli and Thomas Petit

[starsurfer]

Abell 61
http://www.cxielo.ch/gallery/v/nebulae/ ... x.jpg.html
Copyright: Martin Rusterholz

[Ann]

Lovely images, starsurfer. I particularly love the picture of galaxies NGC 5363 and 5364 (I knew it is a spiral stunner, but what a fantastic portrait of it this picture is!!!).

Ann

[starsurfer]

B22 and IC 2087
http://www.straightontillmorning.me/Ast ... 9v8twqm/X2
Copyright: Hytham Abu-Safieh

IC 2087 is the small reflection nebula and B22 is the larger dark nebula.

[starsurfer]

Taurus Molecular Cloud
http://www.nightpixels.net/ic2087_barnard7.htm
Copyright: Richard Galli

Somewhere in this image, B22 and IC 2087 can be found!

[starsurfer]

NGC 1097
http://www.astro-pics.com/1097m.html
Copyright: Wolfgang Promper

Click to view full size image

[starsurfer]

Patchick 58
http://www.pbase.com/skybox/image/164311136
Copyright: Kevin Quin

[Ann]

NGC 4100

Click to view full size image

NGC 4100. Jack Burgess/Adam Block/NOAO/AURA/NSF

Hooray! Adam Block has posted a new galaxy image, this time of galaxy NGC 4100!

Unfortunately, I haven't found a version of his new image that is even close to being small enough to post here. So instead I'm posting his old picture of NGC 4100 (where he collaborated with Jack Burgess to take the picture).

I think the old image is beautiful in itself. And Adam's (and Jack's) old picture of NGC 4100 is a reminder of Adam Block's amazing dedication to producing great pictures of so many galaxies.

Want to see a picture of an NGC galaxy? Chances are that Adam Block has portrayed it. If he hasn't photographed it, there may very well not exist a good picture of it at all.

Thanks a million for all your splendid galaxy portraits, Adam!

Ann