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Collection:
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NASA Spitzer Space Telescope Collection
Collection
NASA Spitzer Space Telescope Collection
Collection
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Title:
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Messier 81
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Description:
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The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this NASA Spitzer Space Telescope image. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years.
Because of its proximity, M81 provides astronomers with an enticing opportunity to study the anatomy of a spiral galaxy in detail. The unprecedented spatial resolution and sensitivity of Spitzer at infrared wavelengths show a clear separation between the several key constituents of the galaxy: the old stars, the interstellar dust heated by star formation activity, and the embedded sites of massive star formation. The infrared images also permit quantitative measurements of the galaxy's overall dust content, as well as the rate at which new stars are being formed.
The infrared image was obtained by Spitzer's infrared array camera. It is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (yellow) and 8.0 microns (red). Winding outward from the bluish-white central bulge of the galaxy, where old stars predominate and there is little dust, the grand spiral arms are dominated by infrared emission from dust. Dust in the galaxy is bathed by ultraviolet and visible light from the surrounding stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles, composed of silicates (which are chemically similar to beach sand) and polycyclic aromatic hydrocarbons, trace the gas distribution in the galaxy. The well-mixed gas (which is best detected at radio wavelengths) and dust provide a reservoir of raw materials for future star formation.
The infrared-bright clumpy knots within the spiral arms denote where massive stars are being born in giant H II (ionized hydrogen) regions. The 8-micron emission traces the regions of active star formation in the galaxy. Studying the locations of these regions with respect to the overall mass distribution and other constituents of the galaxy (e.g., gas) will help identify the conditions and processes needed for star formation. With the Spitzer observations, this information comes to us without complications from absorption by cold dust in the galaxy, which makes interpretation of visible-light features uncertain.
The white stars scattered throughout the field of view are foreground stars within our own Milky Way galaxy.
Description
The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this NASA Spitzer Space Telescope image. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years.
Because of its proximity, M81 provides astronomers with an enticing opportunity to study the anatomy of a spiral galaxy in detail. The unprecedented spatial resolution and sensitivity of Spitzer at infrared wavelengths show a clear separation between the several key constituents of the galaxy: the old stars, the interstellar dust heated by star formation activity, and the embedded sites of massive star formation. The infrared images also permit quantitative measurements of the galaxy's overall dust content, as well as the rate at which new stars are being formed.
The infrared image was obtained by Spitzer's infrared array camera. It is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (yellow) and 8.0 microns (red). Winding outward from the bluish-white central bulge of the galaxy, where old stars predominate and there is little dust, the grand spiral arms are dominated by infrared emission from dust. Dust in the galaxy is bathed by ultraviolet and visible light from the surrounding stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles, composed of silicates (which are chemically similar to beach sand) and polycyclic aromatic hydrocarbons, trace the gas distribution in the galaxy. The well-mixed gas (which is best detected at radio wavelengths) and dust provide a reservoir of raw materials for future star formation.
The infrared-bright clumpy knots within the spiral arms denote where massive stars are being born in giant H II (ionized hydrogen) regions. The 8-micron emission traces the regions of active star formation in the galaxy. Studying the locations of these regions with respect to the overall mass distribution and other constituents of the galaxy (e.g., gas) will help identify the conditions and processes needed for star formation. With the Spitzer observations, this information comes to us without complications from absorption by cold dust in the galaxy, which makes interpretation of visible-light features uncertain.
The white stars scattered throughout the field of view are foreground stars within our own Milky Way galaxy.
Description
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Release Date:
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2003/12/18
Release_Date
2003/12/18
Release Date
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Press Release:
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Press_Release
Press Release
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Release Credit:
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NASA/JPL-Caltech/S. Willner (Harvard-Smithsonian Center for Astrophysics)
Release_Credit
NASA/JPL-Caltech/S. Willner (Harvard-Smithsonian Center for Astrophysics)
Release Credit
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Image Credit:
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NASA/JPL-Caltech/S. Willner (Harvard-Smithsonian Center for Astrophysics)
Image_Credit
NASA/JPL-Caltech/S. Willner (Harvard-Smithsonian Center for Astrophysics)
Image Credit
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Object name:
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M81
Object_name
M81
Object name
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Object name:
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NGC 3031
Object_name
NGC 3031
Object name
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Object name:
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Messier 81
Object_name
Messier 81
Object name
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Object name:
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UGC 5318
Object_name
UGC 5318
Object name
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Object type:
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Spiral galaxy
Object_type
Spiral galaxy
Object type
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Position (J2000):
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*RA: *09h55m33.20s *Dec: *69d03m55.00s
Position_(J2000)
*RA: *09h55m33.20s *Dec: *69d03m55.00s
Position (J2000)
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Distance:
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12,000,000 light-years (3.6 Mpc)
Distance
12,000,000 light-years (3.6 Mpc)
Distance
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Constellation:
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Ursa Major (the Big Bear)
Constellation
Ursa Major (the Big Bear)
Constellation
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Wavelength:
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3.6 (blue), 4.5 (green), 5.8 (yellow), 8.0 (red) microns
Wavelength
3.6 (blue), 4.5 (green), 5.8 (yellow), 8.0 (red) microns
Wavelength
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Image scale:
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23.3 x 17.8 arcmin
Image_scale
23.3 x 17.8 arcmin
Image scale
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Observers:
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Karl D. Gordon, Principal Investigator (University of Arizona)
Steven P. Willner, Principal Investigator (Harvard-Smithsonian Center for Astrophysics)
Almudena Alonso-Herroro (University of Arizona)
Philip Appleton (SSC/Caltech)
Matthew L. N. Ashby (Harvard-Smithsonian Center for Astrophysics)
Pauline Barmby (Harvard-Smithsonian Center for Astrophysics)
Chad Engelbracht (University of Arizona)
Giovanni G. Fazio (Harvard-Smithsonian Center for Astrophysics)
David Frayer (SSC/Caltech)
George Helou (SSC/Caltech)
Joannah Hinz (University of Arizona)
Robert Kennicutt (University of Arizona)
Karl Misselt (University of Arizona)
Michael A. Pahre (Harvard-Smithsonian Center for Astrophysics)
Pablo Perez-Gonzalez (University of Arizona)
George Rieke (University of Arizona)
Marcia Rieke (University of Arizona)
Susan Stolovy (SSC/Caltech)
Lisa Storrie-Lombardi (SSC/Caltech)
Observers
Karl D. Gordon, Principal Investigator (University of Arizona)
Steven P. Willner, Principal Investigator (Harvard-Smithsonian Center for Astrophysics)
Almudena Alonso-Herroro (University of Arizona)
Philip Appleton (SSC/Caltech)
Matthew L. N. Ashby (Harvard-Smithsonian Center for Astrophysics)
Pauline Barmby (Harvard-Smithsonian Center for Astrophysics)
Chad Engelbracht (University of Arizona)
Giovanni G. Fazio (Harvard-Smithsonian Center for Astrophysics)
David Frayer (SSC/Caltech)
George Helou (SSC/Caltech)
Joannah Hinz (University of Arizona)
Robert Kennicutt (University of Arizona)
Karl Misselt (University of Arizona)
Michael A. Pahre (Harvard-Smithsonian Center for Astrophysics)
Pablo Perez-Gonzalez (University of Arizona)
George Rieke (University of Arizona)
Marcia Rieke (University of Arizona)
Susan Stolovy (SSC/Caltech)
Lisa Storrie-Lombardi (SSC/Caltech)
Observers
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Instrument:
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IRAC
Instrument
IRAC
Instrument
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Exposure Date:
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November 6, 2003
Exposure_Date
November 6, 2003
Exposure Date
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Exposure Time:
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50 seconds per position
Exposure_Time
50 seconds per position
Exposure Time
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Orientation:
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North is rotated 91 degrees clockwise from the vertical
Orientation
North is rotated 91 degrees clockwise from the vertical
Orientation
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Magnitude:
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7.9
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facet_what:
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Spitzer Space Telescope
facet_what
Spitzer Space Telescope
facet_what
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facet_what:
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Visible Light
facet_what
Visible Light
facet_what
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facet_what:
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TRACE
facet_what
TRACE
facet_what
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facet_what:
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Ursa Major
facet_what
Ursa Major
facet_what
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facet_what:
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Opportunity
facet_what
Opportunity
facet_what
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facet_what:
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Messier
facet_what
Messier
facet_what
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facet_what:
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Messier 81
facet_what
Messier 81
facet_what
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facet_what:
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Infrared Array Camera (IRAC)
facet_what
Infrared Array Camera (IRAC)
facet_what
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facet_where:
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Arizona
facet_where
Arizona
facet_where
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facet_where:
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Milky Way Galaxy
facet_where
Milky Way Galaxy
facet_where
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facet_where:
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M81
facet_where
M81
facet_where
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facet_where:
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NGC 3031
facet_where
NGC 3031
facet_where
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facet_where:
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Chad
facet_where
Chad
facet_where
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facet_where:
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Jet Propulsion Laboratory (JPL)
facet_where
Jet Propulsion Laboratory (JPL)
facet_where
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facet_where:
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Washington, D.C.
facet_where
Washington, D.C.
facet_where
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facet_where:
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Stennis Space Center (SSC)
facet_where
Stennis Space Center (SSC)
facet_where
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facet_when:
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November 6, 2003
facet_when
November 6, 2003
facet_when
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facet_when_year:
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2003
facet_when_year
2003
facet_when_year
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Image #:
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ssc2003-06c
Image_#
ssc2003-06c
Image #
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original url:
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original_url
original url
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UID:
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SPD-SPITZ-ssc2003-06 c
UID
SPD-SPITZ-ssc2003-06 c
UID
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