WR 102ka
Encyclopedia
WR 102ka also known as the Peony Nebula Star or Peony star is a Wolf-Rayet star
that is one of several candidates for the most luminous known star in our Milky Way
Galaxy. Peony nebula star is a hypergiant
luminous blue variable star. The nearer star Eta Carinae, which was the second brightest star in the sky for a few years in the 19th Century, appears to be slightly more luminous than WR 102ka, but it is known to be a binary star system. There is also the more recently discovered Pistol star
which, like the Peony star, derives its name from the shape of the nebula it is embedded in and which has probably created through heavy mass loss via fierce stellar winds and perhaps also major "mini-supernova-like" eruptions as happened to Eta Carinae around the 1830s-1840s creating the lobes observed by the Hubble Space Telescope
.
The luminosities of the Pistol Star, Eta Carinae and WR 102ka are all rendered somewhat uncertain due to heavy obscuration by galactic dust in the foreground, the effects of which must be corrected for before their apparent brightness can be reduced to estimate their physical radiated power, or "bolometric luminosity".
Both Eta Carinae and WR 102ka are believed likely to explode as supernova
s or hypernova
s within the next few million years.
As is typical of such extremely massive and luminous stars, both have expelled a considerable portion of their initial mass, when originally formed, in dense, massive stellar wind
s.
Because WR 102ka lies near the Galactic Center, it is the more distant and heavily obscured of the two, and is essentially totally obscured in visible wavelengths. Thus it must be observed in longer wavelength infrared light, which is able to penetrate the dust. The Spitzer Space Telescope
observed WR 102ka at wavelengths of 3.6µm, 8µm, and 24µm on April 20, 2005. The observations were carried out by L. Oskinova, W.-R. Hamann, and A. Barniske of Potsdam University
, Germany.
WR 102ka was previously observed by the Two Micron All Sky survey (2MASS) in the near-infrared J, H, and Ks bands, at 1.2µm, 1.58µm, and 2.2µm, respectively.
Wolf-Rayet star
Wolf–Rayet stars are evolved, massive stars , which are losing mass rapidly by means of a very strong stellar wind, with speeds up to 2000 km/s...
that is one of several candidates for the most luminous known star in our Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
Galaxy. Peony nebula star is a hypergiant
Hypergiant
A hypergiant is a star with a tremendous mass and luminosity, showing signs of a very high rate of mass loss.-Characteristics:...
luminous blue variable star. The nearer star Eta Carinae, which was the second brightest star in the sky for a few years in the 19th Century, appears to be slightly more luminous than WR 102ka, but it is known to be a binary star system. There is also the more recently discovered Pistol star
Pistol Star
The Pistol Star is a blue hypergiant and is one of the most luminous known stars in the Milky Way Galaxy.It is one of many massive young stars in the Quintuplet cluster in the Galactic Center region....
which, like the Peony star, derives its name from the shape of the nebula it is embedded in and which has probably created through heavy mass loss via fierce stellar winds and perhaps also major "mini-supernova-like" eruptions as happened to Eta Carinae around the 1830s-1840s creating the lobes observed by the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
.
The luminosities of the Pistol Star, Eta Carinae and WR 102ka are all rendered somewhat uncertain due to heavy obscuration by galactic dust in the foreground, the effects of which must be corrected for before their apparent brightness can be reduced to estimate their physical radiated power, or "bolometric luminosity".
Both Eta Carinae and WR 102ka are believed likely to explode as supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
s or hypernova
Hypernova
Hypernova , also known as a type 1c Supernova, refers to an incredibly large star that collapses at the end of its lifespan...
s within the next few million years.
As is typical of such extremely massive and luminous stars, both have expelled a considerable portion of their initial mass, when originally formed, in dense, massive stellar wind
Stellar wind
A stellar wind is a flow of neutral or charged gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric.Different types of stars have...
s.
Because WR 102ka lies near the Galactic Center, it is the more distant and heavily obscured of the two, and is essentially totally obscured in visible wavelengths. Thus it must be observed in longer wavelength infrared light, which is able to penetrate the dust. The Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
observed WR 102ka at wavelengths of 3.6µm, 8µm, and 24µm on April 20, 2005. The observations were carried out by L. Oskinova, W.-R. Hamann, and A. Barniske of Potsdam University
University of Potsdam
The University of Potsdam is a German university, situated across four campuses in Potsdam, Brandenburg, including the New Palace of Sanssouci and the Park Babelsberg.- Profile :...
, Germany.
WR 102ka was previously observed by the Two Micron All Sky survey (2MASS) in the near-infrared J, H, and Ks bands, at 1.2µm, 1.58µm, and 2.2µm, respectively.
See also
- List of most massive stars
- List of most luminous stars
- LBV 1806-20
- Pistol starPistol StarThe Pistol Star is a blue hypergiant and is one of the most luminous known stars in the Milky Way Galaxy.It is one of many massive young stars in the Quintuplet cluster in the Galactic Center region....
External links
- Tim Thompson's list of luminous stars Somewhat old, but has references.