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Stellar Fireworks Are Ablaze in Galaxy NGC 4449
On July 4, fireworks blaze over the skies of American cities in the annual Independence Day celebrations.
But nearly 12.5 million light-years away in the dwarf galaxy NGC 4449 stellar "fireworks" are going off all the time.
Hundreds of thousands of vibrant blue and red stars blaze in this image taken by NASA's Hubble Space Telescope. Hot bluish-white clusters of massive stars are scattered throughout the galaxy, interspersed with numerous dustier, reddish regions of current star formation. Massive dark clouds of gas and dust are silhouetted against the starlight.
NGC 4449 has been forming stars for several billion years, but currently it is experiencing a star formation event at a much higher rate than in the past. This unusually explosive and intense star formation activity qualifies as a starburst. At the current rate, the gas supply that feeds the stellar production would only last for another billion years or so.
Starbursts usually occur in the central regions of galaxies, but NGC 4449 has more widespread star formation activity, since the very youngest stars are observed both in the nucleus and in streams surrounding the galaxy.
A "global" starburst like NGC 4449 resembles primordial star forming galaxies, which grew by merging with and accreting smaller stellar systems. Since NGC 4449 is close enough to be observed in great detail, it is the ideal laboratory for the investigation of what may have occurred during galactic formation and evolution in the early universe.
It's likely that the current widespread starburst was triggered by interaction or merging with a smaller companion. NGC 4449 belongs to a group of galaxies in the constellation Canes Venatici. Astronomers think that NGC 4449's star formation has been influenced by interactions with several of its neighbors.
Hubble's Advanced Camera for Surveys observed the NGC 4449 in blue, visible, infrared, and H-alpha light.
About the Object
- R.A. PositionR.A. PositionRight ascension – analogous to longitude – is one component of an object's position.12h 28m 10.96s
- Dec. PositionDec. PositionDeclination – analogous to latitude – is one component of an object's position.44° 5' 33.39"
- ConstellationConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.Canes Venatici
- 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.Approximately 13 million light-years (4 Mpc) away.
- DimensionsDimensionsThe physical size of the object or the apparent angle it subtends on the sky.This image is 5 arcminutes (19,000 light-years or 6 kiloparsecs) wide.
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.The Hubble image was created from HST data from proposal 10585: A. Aloisi (STScI/ESA), F. Annibali, C. Leitherer, and J. Mack (STScI), M. Sirianni (STScI/ESA), M. Tosi (INAF, Astronomical Observatory of Bologna), and R. van der Marel (STScI). - InstrumentInstrumentThe science instrument used to produce the data.HST>ACS/WFC
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.November 2005, Exposure Time: 5.3 hours
- FiltersFiltersThe camera filters that were used in the science observations.F435W (B), F555W (V), F658N (Halpha+[N II]), and F814W (I)
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.NGC 4449
- Object DescriptionObject DescriptionThe type of astronomical object.Magellanic dwarf irregular galaxy
- Release DateJuly 3, 2007
- Science ReleaseStellar Fireworks Are Ablaze in Galaxy NGC 4449
- Credits
This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope using several different filters. Three filters were used to sample broad wavelength ranges. One filter was used to sample narrow wavelength emission. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: Blue: F435W (B) Green: F555W (V) Red: F658N (Halpha+[N II]) + F814W (I)
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
