A new color image of the nearby irregular galaxy NGC 6822 shows a myriad
of hot blue massive stars and several famous nebulae in impressive
detail.
NGC 6822 is located approximately 1.6 million light-years from Earth, in
the constellation Sagittarius. A member of the Milky Way galaxy’s Local
Group, it was discovered by E.E. Barnard in the early 1880s. Edwin P.
Hubble conducted the first detailed investigation of the galaxy in 1925,
using the new 100-inch telescope on Mount Wilson. An analysis of these
plates by then-graduate student Susan E. Kayser in 1966 has remained
the most complete study of this galaxy until now.
New images of NGC 6822 in eight filters were taken using the National
Science Foundation’s Blanco 4-meter telescope at Cerro Tololo
Inter-American Observatory (CTIO) near La Serena, Chile, by CTIO staff
members Knut Olsen and Chris Smith.
The images were obtained as part of the NOAO Local Group Galaxies
Survey, one of 13 active survey projects fostered by the National
Optical Astronomy Observatory.
Led by Principal Investigator Phil Massey of Lowell Observatory,
Flagstaff, AZ, the goal of this survey is to obtain comprehensive
imaging of all nearby galaxies in which active star formation is
occurring, enabling studies of the galaxies’ stellar populations and
their gas content. Follow-up spectroscopic studies are planned using
the Gemini North and Gemini South telescopes, the WIYN telescope, and
the Multiple Mirror Telescope.
The 199th meeting of the American Astronomical Society (AAS) in
Washington, DC, marks the first public release of data from the survey.
The images have been processed at Lowell Observatory, a process that
takes many months. This special color rendition of NGC 6822 was made
by Travis Rector of the National Radio Astronomy Observatory.
Shay Holmes, an undergraduate at the College of Charleston, SC,
presents a poster paper at the AAS meeting today on the number of
Hydrogen-II regions in NGC 6822, which have been observed by the survey
with greater area coverage and considerably greater sensitivity than
any previous efforts.
Other members of the Local Group survey team include Paul Hodge
(University of Washington), George Jacoby (WIYN), Nichole King (STScI),
and Abi Saha (Kitt Peak National Observatory/NOAO).
NOAO Image Credit: Local Group Galaxies Survey Team/NOAO/AURA/NSF
This image is available in various electronic file sizes on the
Internet at:
http://www.noao.edu/outreach/press/pr02/0202images.shtml
Detailed information on the Local Group survey (and science-quality
data) is available at:
http://www.lowell.edu/users/massey/lgsurvey.html
Detailed images of the nebulae at the top center edge of the galaxy,
known as Hubble-X and Hubble-V, were released by the Space Telescope
Science Institute’s Hubble Heritage Project on January 4, 2001, and
December 6, 2001, respectively.
CTIO is part of NOAO, which is operated by the Association of
Universities for Research in Astronomy (AURA), Inc., under a
cooperative agreement with the National Science Foundation.
IMAGE CAPTION: [http://www.noao.edu/outreach/press/pr02/0202images.shtml]
A new color image of the nearby irregular galaxy NGC 6822 shows a myriad
of hot blue massive stars and several famous nebulae in impressive detail.
NOAO Image Credit: Local Group Galaxies Survey Team/NOAO/AURA/NSF