AFGL 2298

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.[3] 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
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 00m 10.89s[1]
Declination +03° 45′ 47.1″[1]
Characteristics
Spectral type B8I,[2] B:I:[e],[3] B0-0.5I[4]
Apparent magnitude (J) 12.164[1]
Apparent magnitude (H) 8.918[1]
Apparent magnitude (K) 6.91[5]
Variable type LBV[3]
Astrometry
Distance30,000±10,000 ly
(10,000±3,000[3] pc)
Absolute bolometric
magnitude (Mbol)		−11.25[6]
Details
Radius158 - 385[6] R☉
Luminosity1,300,000 - 2,000,000[6] L☉
Temperature11,000 - 15,500[6] or 26,000[4] K
Other designations
V1672 Aql, RAFGL 2298, IRAS 18576+0341, 2MASS J19001089+0345471[7]
Database references
SIMBADdata

AFGL 2298 has an absolute bolometric magnitude of −11.25,[6] 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.[6] Its status as an LBV was confirmed in 2003.[3]

Like most extremely massive stars, AFGL 2298 is undergoing mass loss.[4] For example, in 2005 it was estimated to be losing 3.7×10−5 solar masses each year,[4] although the rate of mass loss itself varies frequently and dramatically.[6] 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]

Properties of AFGL 2298 over time[6]
Effective temperature (K) Mass loss rate (M☉/yr) Bolometric luminosity (L☉)
June 2001 11,7004.5×10−51.5×106
August 2002 10,9001.2×10−41.3×106
June 2006 10,3005.2×10−52.0×106
May 2007 10,9004×10−51.5×106

See also

References
  1. Cutri, R. M. (2003). "2MASS All-Sky Catalog of Point Sources". VizieR On-line Data Catalog. Bibcode:2003yCat.2246....0C.
  2. Ramírez Alegría, S.; Herrero, A.; Rübke, K.; Marín-Franch, A.; García, M.; Borissova, J. (2018). "Identifying two groups of massive stars aligned in the l 38° Galactic direction". Astronomy and Astrophysics. 614: A116. arXiv:1801.08683. Bibcode:2018A&A...614A.116R. doi:10.1051/0004-6361/201731720. S2CID 119427413.
  3. Clark, J. S.; et al. (2003). "Confirmation of the Luminous Blue Variable nature of AFGL 2298". Astronomy and Astrophysics. 403 (2): 653–658. Bibcode:2003A&A...403..653C. doi:10.1051/0004-6361:20030389.
  4. Umana, G.; Buemi, C. S.; Trigilio, C.; Leto, P. (2005). "Current day mass loss rate for Luminous Blue Variable IRAS 18576+0341". Astronomy and Astrophysics. 437 (1): L1–L5. Bibcode:2005A&A...437L...1U. doi:10.1051/0004-6361:200500126.
  5. Kazarovets, E. V. (2006). "The 78th Name-List of Variable Stars". Information Bulletin on Variable Stars. 5721: 1. Bibcode:2006IBVS.5721....1K.
  6. Clark, J. S.; et al. (2009). "Bolometric luminosity variations in the luminous blue variable AFGL2298". Astronomy and Astrophysics. 507 (3): 1555–1565. arXiv:0909.4160. Bibcode:2009A&A...507.1555C. doi:10.1051/0004-6361/200912358. S2CID 119187994.
  7. "AFGL 2298". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 26 January 2017.
  8. Buemi, C. S.; et al. (2010). "VISIR/VLT and VLA Joint Imaging Analysis of the Circumstellar Nebula Around IRAS 18576+0341". The Astrophysical Journal. 721 (2): 1404–1411. arXiv:1008.0997. Bibcode:2010ApJ...721.1404B. doi:10.1088/0004-637X/721/2/1404. S2CID 119281049.
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