Dwarf galaxies in Pisces

The NASA/ESA 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' colours reveals that the galaxies contain about 20 to 30 bright blue stars. The blue colour 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 centre 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 30 October, 2014, by Hubble's Advanced Camera for Surveys. The image of Pisces B was taken on 8 November, 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.

Links:

Credit:

NASAESA, and E. Tollerud (STScI)

About the Image

NASA press release
NASA caption
Id:opo1629a
Type:Collage
Release date:12 August 2016, 12:49
Size:3000 x 2400 px

About the Object

Name:Pisces
Type:Local Universe : Galaxy : Type : Irregular
Local Universe : Galaxy : Size : Dwarf
Category:Galaxies

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Colours & filters

BandWavelengthTelescope
Optical
V
606 nm Hubble Space Telescope
ACS
Infrared
I
814 nm Hubble Space Telescope
ACS

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