| NASA Center: |
Hubble Space Telescope Center |
|---|
| Image # : |
PR99-19 |
|---|
| Date : |
05/01/1999
|
|---|
|
Title
Variable Stars in a Distant Spiral Galaxy
Full Description
A NASA Hubble Space Telescope (HST) view of the magnificent spiral
galaxy NGC 4603, the most distant galaxy in which a special class of
pulsating stars called Cepheid variables have been found. It is
associated with the Centaurus cluster, one of the most massive
assemblages of galaxies in the nearby universe.
The Local Group of galaxies, of which the Milky Way is a member, is
moving in the direction of Centaurus at a speed of more than a million
miles an hour under the influence of the gravitational pull of the
matter in that direction. Clusters of young bright blue stars highlight
the galaxy's spiral arms. In contrast, red giant stars in the process
of dying are also found. Only the very brightest stars in NGC 4603 can
be seen individually, even with the unmatched ability of the Hubble
Space Telescope to obtain detailed images of distant objects. Much of
the diffuse glow comes from fainter stars that cannot be individually
distinguished by Hubble. The reddish filaments are regions where clouds
of dust obscure blue light from the stars behind them.
This galaxy was observed by a team affiliated with the HST Key Project
on the Extragalactic Distance Scale. Because NGC 4603 is much farther
away than the other galaxies studied with Hubble by the Key Project
team, 108 million light-years, its stars appear very faint from the
Earth, and so accurately measuring their brightness, as is required for
distinguishing the characteristic variations of Cepheids, is extremely
difficult. Determining the distance to the galaxy required an
unprecedented statistical analysis based on extensive computer
simulations.
Keywords
Hubble Space Telescope HST Spiral Galaxy NGC 4603 Pulsar Cepheid Centaurus Milky Way
Subject Category
Deep Space Studies, Hubble,
Reference Numbers
- Center:
HSTI
- Center Number:
PR99-19
- GRIN DataBase Number:
GPN-2000-000940
Source Information
- Creator/Photographer: NASA, HST Key Project Team
- Original Source: DIGITAL
| Resolution | Format | Width
(Pixels) | Height
(Pixels) | Size
(KBytes) |
Thumbnail |
.jpg |
82 |
46 |
9 |
Small |
.jpg |
584 |
324 |
168 |
Medium |
.jpg |
1368 |
760 |
957 |
Large |
.jpg |
1368 |
760 |
955 |
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Updated October 31, 2002
• History Questions: NASA History Office
• Responsible NASA Official: Steve Garber
• Author: Michael Hahn. Editor: Dwayne A. Day
• Curator & Technical Questions: Erin Needham
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