Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Aquila |
Right ascension | 19h 00m 10.89s [2] |
Declination | +03° 45′ 47.1″ [2] |
Characteristics | |
Spectral type | B8I, [3] B:I:[e], [4] B0-0.5I [5] |
Apparent magnitude (J) | 12.164 [2] |
Apparent magnitude (H) | 8.918 [2] |
Apparent magnitude (K) | 6.91 [6] |
Variable type | LBV [4] |
Astrometry | |
Distance | 30,000±10,000
ly (10,000±3,000 [4] pc) |
Absolute bolometric magnitude (Mbol) | −11.25 [1] |
Details | |
Radius | 158 - 385 [1] R☉ |
Luminosity | 1,300,000 - 2,000,000 [1] L☉ |
Temperature | 11,000 - 15,500 [1] or 26,000 [5] K |
Other designations | |
Database references | |
SIMBAD | data |
AFGL 2298, also known as IRAS 18576+0341, is a luminous blue variable star (LBV) located in the constellation Aquila, very close to the galactic plane. Its distance is not well known; it may be anywhere between 23,000 and 42,000 light years (7,000 to 13,000 parsecs) away from the Earth. [4] Despite being extremely luminous, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands; in fact, in visual wavelengths it is completely undetectable. [7]
AFGL 2298 has an absolute bolometric magnitude of −11.25, [1] making it one of the most luminous stars known. Indeed, many of the hottest and most luminous stars known are luminous blue variables and other early-type stars. However, like all LBVs, AFGL 2298 is highly variable and the bolometric magnitude refers to its peak luminosity. [1] Its status as an LBV was confirmed in 2003. [4]
Like most extremely massive stars, AFGL 2298 is undergoing mass loss. [5] For example, in 2005 it was estimated to be losing 3.7×10−5 solar masses each year, [5] although the rate of mass loss itself varies frequently and dramatically. [1] The stellar mass is currently being ejected as a nebula around the star (similar to AG Carinae), which was imaged by the Very Large Telescope in 2010. [8] The nebula was found to be fairly circular, and the properties of the dust appeared to be constant throughout the entire nebula. [8]
Effective temperature (K) | Mass loss rate (M☉/yr) | Bolometric luminosity (L☉) | |
---|---|---|---|
June 2001 | 11,700 | 4.5×10−5 | 1.5×106 |
August 2002 | 10,900 | 1.2×10−4 | 1.3×106 |
June 2006 | 10,300 | 5.2×10−5 | 2.0×106 |
May 2007 | 10,900 | 4×10−5 | 1.5×106 |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Aquila |
Right ascension | 19h 00m 10.89s [2] |
Declination | +03° 45′ 47.1″ [2] |
Characteristics | |
Spectral type | B8I, [3] B:I:[e], [4] B0-0.5I [5] |
Apparent magnitude (J) | 12.164 [2] |
Apparent magnitude (H) | 8.918 [2] |
Apparent magnitude (K) | 6.91 [6] |
Variable type | LBV [4] |
Astrometry | |
Distance | 30,000±10,000
ly (10,000±3,000 [4] pc) |
Absolute bolometric magnitude (Mbol) | −11.25 [1] |
Details | |
Radius | 158 - 385 [1] R☉ |
Luminosity | 1,300,000 - 2,000,000 [1] L☉ |
Temperature | 11,000 - 15,500 [1] or 26,000 [5] K |
Other designations | |
Database references | |
SIMBAD | data |
AFGL 2298, also known as IRAS 18576+0341, is a luminous blue variable star (LBV) located in the constellation Aquila, very close to the galactic plane. Its distance is not well known; it may be anywhere between 23,000 and 42,000 light years (7,000 to 13,000 parsecs) away from the Earth. [4] Despite being extremely luminous, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands; in fact, in visual wavelengths it is completely undetectable. [7]
AFGL 2298 has an absolute bolometric magnitude of −11.25, [1] making it one of the most luminous stars known. Indeed, many of the hottest and most luminous stars known are luminous blue variables and other early-type stars. However, like all LBVs, AFGL 2298 is highly variable and the bolometric magnitude refers to its peak luminosity. [1] Its status as an LBV was confirmed in 2003. [4]
Like most extremely massive stars, AFGL 2298 is undergoing mass loss. [5] For example, in 2005 it was estimated to be losing 3.7×10−5 solar masses each year, [5] although the rate of mass loss itself varies frequently and dramatically. [1] The stellar mass is currently being ejected as a nebula around the star (similar to AG Carinae), which was imaged by the Very Large Telescope in 2010. [8] The nebula was found to be fairly circular, and the properties of the dust appeared to be constant throughout the entire nebula. [8]
Effective temperature (K) | Mass loss rate (M☉/yr) | Bolometric luminosity (L☉) | |
---|---|---|---|
June 2001 | 11,700 | 4.5×10−5 | 1.5×106 |
August 2002 | 10,900 | 1.2×10−4 | 1.3×106 |
June 2006 | 10,300 | 5.2×10−5 | 2.0×106 |
May 2007 | 10,900 | 4×10−5 | 1.5×106 |