Shychemist

Astronomy team discovers nearby dwarf galaxy

NGC 4449 and companion

A team led by UCLA research astronomer Michael Rich has used a unique telescope to discover a previously unknown companion to the nearby galaxy NGC 4449, which is some 12.5 million light years from Earth. The newly discovered dwarf galaxy had escaped even the prying eyes of the Hubble Space Telescope.

The research is published Feb. 9 in the journal Nature.

The larger, host galaxy, NGC 4449, may be “something of a living fossil,” representing what most galaxies probably looked like shortly after the Big Bang, Rich said. The galaxy is forming stars “so furiously” that it has giant clusters of young stars and even appears bluish — a sign of a young galaxy — to the eye in large amateur telescopes, he said.

NGC 4449 has a nucleus that may someday host a black hole and an irregular structure, lacking the spiral arms characteristic of many galaxies, he said. It is surrounded by a huge complex of hydrogen gas that spans approximately 300,000 light years, which may be fueling its burst of star formation.

Rich collaborated with Francis Longstaff, a professor of finance at the UCLA Anderson School of Management and an amateur astronomer, in acquiring and using a specialized telescope designed to take images of wide fields of the sky. Known as the Centurion 28 (the diameter of the mirror is 28 inches), the telescope, and the observatory the astronomers used, are located at the Polaris Observatory Association near Frazier Park, in Kern County, Calif.

With the C28 telescope, the astronomers discovered the companion dwarf galaxy, which has “evidently experienced a close encounter with the nucleus of NGC 4449,” Rich said. Dubbed NGC 4449B, the dwarf galaxy has been stretched into a comet-like shape by this gravitational encounter.

NGC 4449B had remained undetected because it is more than 10 times fainter than the natural brightness of the night sky and some 1,000 times fainter than our own Milky Way galaxy. The dwarf galaxy is in a “transient stage,” Rich said, and will soon — by astronomical standards — be dissolved.

The Milky Way has a similar companion, known as the Sagittarius Dwarf galaxy, which has been wrapped around our galaxy as it orbits and which loses its stars to the Milky Way’s gravitational tug.

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