Detail View: NASA Hubble Space Telescope Collection: Hubble Finds 'Dorian Gray' Galaxy

Hubble Finds 'Dorian Gray' Galaxy

I Zw 18

*Credit:* NASA [ http://www.nasa.gov/ ], ESA [ http://www.spacetelescope.org/ ], and A. Aloisi (Space Telescope Science Institute [ http://www.stsci.edu/ ] and European Space Agency [ http://www.spacetelescope.org/ ], Baltimore, Md.)

Technical facts about this news release: About the Object Object Name: I Zwicky 18, I Zw 18 Object Description: Galaxy Position (J2000): R.A. 09h 34m 1s.90 Dec. +55° 14' 26 ".00 Constellation: Ursa Major Distance: Approximately 60 million light-years (18 Megaparsecs) away. Dimensions: This image is roughly 1.7 arcminutes (29,000 light-years or 9 kiloparsecs) wide. About the Data Data Description: The Hubble image was created from HST data from proposal 10586: A. Aloisi (STScI/ESA), G. Clementini (Astronomical Observatory of Bologna), M. Marconi and I. Musella (Astronomical Observatory of Capodimonte, Italy), A. Saha (National Optical Astronomy Observatories/AURA), M. Sirianni (STScI/ESA), M. Tosi (Astronomical Observatory of Bologna), and R. van der Marel (STScI). The science team comprises A. Aloisi and M. Sirianni (STScI/ESA), F. Annibali, J. Mack, and R. van der Marel (STScI), A. Saha (National Optical Astronomy Observatories/AURA), and G. Clementini, R. Contreras, G. Fiorentino, M. Marconi, I. Musella, and M. Tosi (Italian National Astrophysics Institutes in Bologna and Naples). Instrument: ACS/WFC Exposure Date(s): October 2005 - January 2006 Exposure Time: 15 hours Filters: F660W (V) and F814W (I) About the Image Image Credit: NASA, ESA, and A. Aloisi (STScI/ESA) Release Date: October 16, 2007 Color: This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope. Two filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: F660W (V) cyan F814W (I) orange Orientation/Scale: Hubble Finds Mature Galaxy Masquerading as Toddler [ http://imgsrc.hubblesite.org/hu/db/2007/35/images/a/formats/compass_large_web.jpg ]

*Description*: NASA's Hubble Space Telescope quashed the possibility that what was previously believed to be a toddler galaxy in the nearby universe may actually be considered an adult. Called I Zwicky 18, this galaxy has a youthful appearance that resembles galaxies typically found only in the early universe. Hubble has now found faint, older stars within this galaxy, suggesting that the galaxy may have formed at the same time as most other galaxies. I Zwicky 18 is classified as a dwarf irregular galaxy and is much smaller than our Milky Way Galaxy. The concentrated bluish-white knots embedded in the heart of the galaxy are two major starburst regions where stars are forming at a furious rate. The wispy blue filaments surrounding the central starburst regions are bubbles of gas that have been blown away by stellar winds and supernovae explosions from a previous generation of hot, young stars. This gas is now heated by intense ultraviolet radiation unleashed by a new generation of hot, young stars. A companion galaxy lies just above and to the left of I Zwicky 18. The companion may be interacting with I Zwicky 18 by gravitationally tugging on the galaxy. The interaction may have triggered the galaxy's recent star formation that is responsible for the youthful appearance. Besides the bluish-white young stars, white-reddish stars also are visible in both I Zwicky 18 and its companion. These stars may be as old as 10 billion years. The reddish extended objects surrounding I Zwicky 18 and its companion are ancient, fully formed galaxies of different shapes that are much farther away. Hubble data also allowed astronomers for the first time to identify Cepheid variable stars in I Zwicky 18. These flashing stellar mile-markers were used to determine that I Zwicky 18 is 59 million light-years from Earth, almost 10 million light-years more distant than previously believed. The observations of I Zwicky 18 were taken in 2005 and 2006 with Hubble's Advanced Camera for Surveys. Astronomers made this image by combining observations taken with blue and red filters. The science team consists of Alessandra Aloisi and Marco Sirianni of the Space Telescope Science Institute and the European Space Agency; Francesca Annibali, Jennifer Mack, and Roeland van der Marel of the Space Telescope Science Institute; Abhijit Saha of the National Optical Astronomy Observatories; and Gisella Clementini, Rodrigo Contreras, Giuliana Fiorentino, Marcella Marconi, Ilaria Musella, and Monica Tosi of the Italian National Astrophysics Institutes in Bologna and Naples.

Advanced Camera for Surveys

I Zwicky 18

2005

2005

SPD-HUBBLE-STScI-2007-35a

http://hubblesite.org/newscenter/archive/releases/2007/35/image/a/

October 16, 2007 10:00 AM (EDT)