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Tightly Wound Arms of Dust Encircle Nucleus of Galaxy NGC 2787
Tightly wound, almost concentric, arms of dark dust encircle the bright nucleus of galaxy NGC 2787 in this NASA Hubble Space Telescope image created by the Hubble Heritage Team.
In astronomer Edwin Hubble's galaxy classification scheme, NGC 2787 is classified as an SB0, a barred lenticular galaxy. These lens-shaped galaxies show little or no evidence of the grand spiral arms that occur in their more photogenic cousins, though NGC 2787 does sport a faint bar, not apparent in this image.
NGC 2787's seemingly bland qualities are, however, just what the doctor ordered for astronomer Marcella Carollo's investigation. Dr. Carollo (Swiss Federal Institute of Technology, Zurich) and team used Hubble to look at the center of these galaxies for clues about the process of galaxy formation including the role of galaxy collisions and central black holes.
Also visible in the Heritage image are about a dozen globular clusters hovering around NGC 2787. What appear to be stars are, in fact, gravitationally bound families of 100,000's of ancient stars orbiting the center of NGC 2787.
NGC 2787 lies roughly 24 million light-years (7.4 megaparsecs) from Earth in the constellation Ursa Major. Data was collected with the Wide Field Planetary Camera 2 in January 1999. This Heritage image was made by combining light from blue, green and infrared filters from the 1999 dataset.
About the Object
- R.A. PositionR.A. PositionRight ascension – analogous to longitude – is one component of an object's position.09h 19m 18.9s
- Dec. PositionDec. PositionDeclination – analogous to latitude – is one component of an object's position.69° 12' 11.9"
- ConstellationConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.Ursa Major
- DistanceDistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.About 24 million light-years (7.4 megaparsecs)
- DimensionsDimensionsThe physical size of the object or the apparent angle it subtends on the sky.The image is roughly 38 arcseconds (4400 light-years or 1300 parsecs) across.
About the Data
- Data DescriptionData DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.Principal Astronomers: M. Carollo (Swiss Federal Institute of Technology, Zurich) - InstrumentInstrumentThe science instrument used to produce the data.HST>WFPC2
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.January 29, 1999, Exposure Time: 1.2 hours
- FiltersFiltersThe camera filters that were used in the science observations.F450W (Wide B), F555W (V), F814W (I)
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.NGC 2787
- Object DescriptionObject DescriptionThe type of astronomical object.Galaxy with Spiral Arm Structure
- Release DateApril 4, 2002
- Science ReleaseA Galaxy That’s All Wound Up
- CreditNASA and The Hubble Heritage Team (STScI/AURA); Acknowledgment: M. Carollo (Swiss Federal Institute of Technology, Zurich)

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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov