by Ann » Sun Jul 29, 2012 8:40 pm
neufer wrote:The
Westerlund 1 super star cluster has never gotten an APOD
![Exclamation :!:](./images/smilies/icon_exclaim.gif)
http://en.wikipedia.org/wiki/Westerlund_1 wrote:
Wd1 is too remote for direct measurement of the distance via parallax measurements, and the distance must be estimated from the expected absolute magnitude of the stars and estimates of the extinction towards the cluster. This has been done for both the yellow hypergiant[2] and Wolf–Rayet[6] populations, yielding estimates around 5 kpc in both cases, while a determination from the main-sequence population suggests 3.6 kpc.[7]
These estimates all place Wd1 near the outer edge of the Galactic bar, which may be significant in determining how such a massive cluster formed.
Interesting. It is not uncommon for barred galaxies to show enhanced star formation near one or both ends of the bar. Two such examples are
NGC 1530 and
NGC 7496. An even more perfect example is
NGC 6217 by Hubble. Please note the huge cluster at the lower left, right at one end of the bar.
© Kuiper Airborne Observatory NASA-714
But an even more fascinating example is, in fact, R136 itself, the massive cluster in today's APOD. While not situated exactly
at the end of the bar of LMC, it is clearly situated
near the end of the bar of LMC.
It is interesting to think that Westerlund 1 may be the R136 cluster of the bar of the Milky Way.
Ann
[quote="neufer"]The [url=http://en.wikipedia.org/wiki/Westerlund_1]Westerlund 1[/url] super star cluster has never gotten an APOD :!:[/quote]
[quote]http://en.wikipedia.org/wiki/Westerlund_1 wrote:
Wd1 is too remote for direct measurement of the distance via parallax measurements, and the distance must be estimated from the expected absolute magnitude of the stars and estimates of the extinction towards the cluster. This has been done for both the yellow hypergiant[2] and Wolf–Rayet[6] populations, yielding estimates around 5 kpc in both cases, while a determination from the main-sequence population suggests 3.6 kpc.[7] [b][i][color=#FF8000][size=105]These estimates all place Wd1 near the outer edge of the Galactic bar[/size][/color][/i][/b], which may be significant in determining how such a massive cluster formed.[/quote]
Interesting. It is not uncommon for barred galaxies to show enhanced star formation near one or both ends of the bar. Two such examples are [url=http://www.naoj.org/Gallery/hdtv/ngc1530.jpg]NGC 1530[/url] and [url=http://citadel.pioner-samara.ru/ft/ngc7496c.jpg]NGC 7496[/url]. An even more perfect example is [url=http://www.nasa.gov/images/content/384938main_ero_teaser_ngc6217_4x3_946-710.jpg]NGC 6217[/url] by Hubble. Please note the huge cluster at the lower left, right at one end of the bar.
[float=left][img2]http://www.museevirtuel-virtualmuseum.ca/media/edu/EN/uploads/image/LO5DA24107316044984440236.jpg[/img2][c][size=80]© Kuiper Airborne Observatory NASA-714[/size][/c][/float]But an even more fascinating example is, in fact, R136 itself, the massive cluster in today's APOD. While not situated exactly [i]at[/i] the end of the bar of LMC, it is clearly situated [i]near[/i] the end of the bar of LMC.
It is interesting to think that Westerlund 1 may be the R136 cluster of the bar of the Milky Way.
Ann