HD 168607

HD 168607
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 21m 14.889s[1]
Declination −16° 22′ 31.76″[1]
Apparent magnitude (V) 8.28[2] (var)
Characteristics
Spectral type B9Ia+[3]
U−B color index 0.41[2]
B−V color index 1.54[2]
J−K color index 1.06[2]
Variable type LBV[4]
Astrometry
Radial velocity (Rv)-30[5] km/s
Proper motion (μ) RA: -0.27[1] mas/yr
Dec.: -1.01[1] mas/yr
Parallax (π)1.85 ± 1.29[1] mas
Distanceapprox. 2,000 ly
(approx. 500 pc)
Absolute magnitude (MV)−8.4[6]
Details
Luminosity240,000[6] L☉
Surface gravity (log g)1.0[6] cgs
Temperature9,300[6] K
Other designations
V4029 Sgr, HD  168607, BD -16°4829, SAO 161374, HIP 89956, AAVSO 1815-16
Database references
SIMBADdata
HD 168607 is the right star of the pair below the Omega Nebula. The other is the hypergiant HD 168625.

HD 168607 (V4029 Sgr) is a blue hypergiant and luminous blue variable (LBV) star located in the constellation of Sagittarius, easy to see with amateur telescopes. It forms a pair with HD 168625, also a blue hypergiant and possible luminous blue variable, that can be seen at the south-east of M17, the Omega Nebula.

Physical properties

HD 168607 is usually assumed to be at the same distance of the Omega Nebula (2.2 kiloparsecs, 7,200 light years, from the Sun) and may be physically associated with HD 168625.[7] Assuming this distance is correct, this star [8] is 240,000 times brighter than the Sun with a surface temperature of 9300 K.[8] Its apparent magnitude has a variation of 0.25-0.30 m. with a period of 64 days, but no outburst has been observed.[9] Unlike its neighbour HD 168625, no nebula has been found around this star.[10]

References

  1. 1 2 3 4 5 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
  3. ↑ Chentsov, E. L.; Ermakov, S. V.; Klochkova, V. G.; Panchuk, V. E.; Bjorkman, K. S.; Miroshnichenko, A. S. (2003). "An atlas of spectra of B6-A2 hypergiants and supergiants from 4800 to 6700Å". Astronomy and Astrophysics. 397 (3): 1035–1042. Bibcode:2003A&A...397.1035C. doi:10.1051/0004-6361:20021430.
  4. ↑ Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics. 538: A47. arXiv:1111.6375Freely accessible. Bibcode:2012A&A...538A..47N. doi:10.1051/0004-6361/201118040.
  5. ↑ Kharchenko, N. V.; Scholz, R.-D.; Piskunov, A. E.; Röser, S.; Schilbach, E. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878Freely accessible. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776.
  6. 1 2 3 4 Van Genderen, A. M.; Van Den Bosch, F. C.; Dessing, F.; Fehmers, G. C.; Van Grunsven, J.; Van Der Heiden, R.; Janssens, A. M.; Kalter, R.; Van Der Meer, R. L. J.; Van Ojik, R.; Smit, J. M.; Zijderveld, M. J. (1992). "Light variations of massive stars (Alpha Cygni variables). XIII - the B-type hypergiants R81 (LBV), HD 80077 (LBV?), HD 168607 = V 4029 Sagittarii (LBV) and HD 168625 = V 4030 Sagittarii". Astronomy and Astrophysics. 264: 88. Bibcode:1992A&A...264...88V.
  7. ↑ Chentsov, E.L.; Gorda, E.S. (2004). "Spatial Closeness of the White Hypergiants HD 168607 and HD 168625". Astronomy Letters. 30 (7): 145–180. Bibcode:2004AstL...30..461C. doi:10.1134/1.1774398.
  8. 1 2 van Genderen, A.M. (2001). "S Doradus variables in the Galaxy and the Magellanic Clouds". Astronomy & Astrophysics. 366 (2): 508–531. Bibcode:2001A&A...366..508V. doi:10.1051/0004-6361:20000022.
  9. ↑ Sterken, C.; Arentoft, T.; Duerbeck, H.W.; Brogt, E. (1999). "Light variations of the blue hypergiants HD 168607 and HD 168625 (1973-1999)". Astronomy & Astrophysics. 349: 532–536. Bibcode:1999A&A...349..532S.
  10. ↑ Hutsemekers, D.; vanDrom, E.; Gosset, E.; Melnick, J. (1994). "A dusty nebula around the luminous blue variable candidate HD 168625". Astronomy and Astrophysics. 2904: 906–914. Bibcode:1994A&A...290..906H.
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