NASA's Hubble Space Telescope has captured the glow of new stars in these small, ancient galaxies. Pisces A is on the left and Pisces B is on the right.
Astronomers estimate that less than 100 million years ago both galaxies doubled their star-formation rate. An analysis of the stars' colors reveals that the galaxies contain about 20 to 30 bright blue stars. The blue color is a sign they are young, less than 100 million years old. Each galaxy contains about 10 million stars.
In the image of Pisces A, at left, the bright object at the top of the image is a distant background galaxy. Other distant background galaxies are visible as bright dots.
In the image of Pisces B, at right, the bright object with the diffraction spikes below left of center is a foreground star in our Milky Way galaxy. Several distant background galaxies are also visible.
Hubble observations suggest that Pisces A and Pisces B should have produced the bulk of their stars long ago. But the puny galaxies dwelled for billions of years in the Local Void, a region of the universe sparsely populated with galaxies. Now the galaxies have moved into a region packed with galaxies and intergalactic gas. This dense environment is triggering star birth.
Pisces A is roughly 19 million light-years away and Pisces B about 30 million light-years away.
The image of Pisces A was taken on Oct. 30, 2014, by Hubble's Advanced Camera for Surveys. The image of Pisces B was taken on Nov. 8, 2014, by Hubble's Advanced Camera for Surveys.
The science team consists of Erik J. Tollerud, Space Telescope Science Institute (STScI), Baltimore, Maryland; Marla C. Geha, Yale University, New Haven, Connecticut; Jana Grcevich, American Museum of Natural History, New York, New York; Mary E. Putman, Columbia University, New York, New York; Daniel R. Weisz, University of Washington, Seattle; and Andrew E. Dolphin, Raytheon Co., Tucson, Arizona.
Credits
NASA, ESA, and E. Tollerud (STScI)| About The Object | |
|---|---|
| Object Name | Pisces A (left), Pisces B (right) |
| Object Description | Dwarf galaxy |
| R.A. Position | 00h 14m 46.0s (Pisces A), 01h 19m 11.7s (Pisces B) |
| Dec. Position | +10° 48' 47.01" (Pisces A), +11° 07' 18.22" (Pisces B) |
| Constellation | Pisces |
| Distance | 18.4 million light-years (Pisces A), 29.0 million light-years (Pisces B) |
| About The Data | |
| Data Description | Data were provided by HST proposal : E. Tollerud (STScI), M. Geha (Yale University), J. Grcevich (AMNH), M. Putman (Columbia University), and D. Stern (JPL). The science team also includes D. Weisz (University of Washington) and A. Dolphin (Raytheon). |
| Instrument | HST>ACS/WFC |
| Exposure Dates | October 30, 2014, Exposure Time: 2,132 seconds (Pisces A), November 8, 2014, Exposure Time: 2,092 seconds (Pisces B) |
| Filters | F606W (wide V), F814W (I) |
| About The Image | |
| Color Info | These images are each composites of separate exposures acquired by the ACS/WFC instrument. Two filters were used to sample different wavelength bands. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Cyan-blue: F606W (wide V) Red-orange: F814W (I) |
| Compass Image |  |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The 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. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
