NGC 300
Distance: 6.5 Million Light Years

Right Ascension: 00 : 54.9 (hours : minutes)
Declination: -37 : 41 (degrees : minutes)

text copyright Robert Gendler

The Sculptor group is the nearest galactic group to the local group and has five major spiral galaxies including NGC 300, NGC 253, NGC 247, NGC 55, and NGC 7793. It also contains some 20 dwarf galaxies. NGC 300 is a bright nearly face-on spiral similar to M33. Because of its proximity and face-on orientation much is known about NGC 300. The outer regions of NGC 300 show a very large mass to luminosity ratio suggesting a massive halo of dark matter sustains the rotational curve of the outer disk.

NGC 300 has been the subject of exhaustive searches for extragalactic Wolf-Rayet stars. Wolf-Rayet stars (WR) are of interest to astronomers as they represent a late evolutionary phase of very massive O type giants with masses greater than 25 suns. They are extremely hot and luminous with temperatures exceeding 50,000 degrees K. and some with luminosities approaching one million suns. WR stars are a rare and exotic breed of stars, dominated by helium rather than hydrogen. Only one in ten million stars is a WR star. Astronomers search for WR stars in other galaxies by detecting specific helium emission lines. Perhaps the most defining feature of Wolf-Rayet stars is their immense stellar winds. The fierce stellar winds can drive extraordinary mass loss rates of one millionth to one hundred thousandth of a solar mass per year (equivalent to an earth sized planet), a rate 3 or 4 time greater than typical O type giants and 10 billion times stronger than our suns stellar wind.

Over a dozen WR candidate stars have been identified within NGC 300. Despite their limited numbers (one in ten million stars is a WR star) they contribute substantially to the ecology of galaxies. WR stars inject the elemental products of their hydrogen and helium burning into the interstellar medium. In this way WR stars contribute to the chemical enrichment of a galaxy by infusing the galactic disk with heavier elements such as carbon, oxygen, neon, nitrogen, and magnesium. These elements will then become incorporated into subsequent generations of stars and possibly their planet progeny. Heavier elements are essential to the evolution of living organisms so its not far fetched to think that ancient WR stars might have played a role in the establishment of life on earth.

(See NGC 2359 for more information on Wolf-Rayet stars)