Jump to content

HD 168625: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
m even more concise, kept data way of doing things. Also spare full stop (period) hanging.
m →Distance: the subject is plain - it is the ARTICLE. Another spare point found.
Line 44: Line 44:


==Distance==
==Distance==
The distance of HD 168625 and its association with the Omega Nebula and HD 168607 is in doubt; while some authors think both stars are physically associated and belong to the [[stellar association]] [[Serpens OB1]],<ref name=Chentsov2004/> at a distance to the [[Sun]] of {{convert|2.2|kpc|ly|lk=on}},<ref name=Naze2011/> or for both per [[Gaia Data Release 2]] about {{convert|1.6|kpc|ly}}.<ref name=dr2/>, a 2002 study estimates HD 168625 is farther, at about {{convert|2.8|kpc|ly}} and unrelated to the other two objects.<ref name=Pasquali2002/>
The distance of HD 168625 and its association with the Omega Nebula and HD 168607 is in doubt; while some authors think both stars are physically associated and belong to the [[stellar association]] [[Serpens OB1]],<ref name=Chentsov2004/> at a distance to the [[Sun]] of {{convert|2.2|kpc|ly|lk=on}},<ref name=Naze2011/> or for both per [[Gaia Data Release 2]] about {{convert|1.6|kpc|ly}},<ref name=dr2/> a 2002 study estimates this star is farther, at about {{convert|2.8|kpc|ly}} and unrelated to the other two objects.<ref name=Pasquali2002/>


== Physical characteristics ==
== Physical characteristics ==

Revision as of 18:33, 5 January 2021

HD 168625
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 21m 19.548s[1]
Declination −16° 22′ 16.0572″[1]
Apparent magnitude (V) 8.30–8.41[2]
Characteristics
Spectral type B6Ia+[3] (B2—B8[4])
U−B color index +0.37[5]
B−V color index +1.41[5]
J−K color index 0.599
Variable type α Cygni[6]
Astrometry
Radial velocity (Rv)−4.00[7] km/s
Proper motion (μ) RA: −0.71±1.20[1] mas/yr
Dec.: +0.01±0.74[1] mas/yr
Parallax (π)0.6212 ± 0.0640 mas[8]
Distanceapprox. 5,300 ly
(approx. 1,600 pc)
Absolute magnitude (MV)−8.39[4]
Details[4]
Luminosity380,000 L☉
Surface gravity (log g)1.74 cgs
Temperature14,000 K
Rotational velocity (v sin i)60 km/s
Other designations
V4030 Sgr, HD 168625, BD −16°4830, SAO 161375, HIP 89963, AAVSO 1815-168
Database references
SIMBADdata

HD 168625 (V4030 Sagittarii) is a blue hypergiant star and candidate luminous blue variable located in the constellation of Sagittarius easy to see with amateur telescopes. It forms a visual pair with the also blue hypergiant (and luminous blue variable) HD 168607 and is located to the south-east of M17, the Omega Nebula.

Distance

The distance of HD 168625 and its association with the Omega Nebula and HD 168607 is in doubt; while some authors think both stars are physically associated and belong to the stellar association Serpens OB1,[9] at a distance to the Sun of 2.2 kiloparsecs (7,200 ly),[10] or for both per Gaia Data Release 2 about 1.6 kiloparsecs (5,200 ly),[8] a 2002 study estimates this star is farther, at about 2.8 kiloparsecs (9,100 ly) and unrelated to the other two objects.[11]

Physical characteristics

Assuming a distance of 2.2 kiloparsecs, HD 168625 is 220,000 times brighter than the Sun, having a surface temperature of 12,000 K.[10] It is losing mass through a very strong stellar wind at a rate of roughly 1.46×10−6 solar masses per year[12] and observations realized in 2012 with the help of the VLT show it's actually a binary star,[13] with the companion being around 4.5 magnitudes fainter than the primary.[14]

Nebula

HD 168625 is the left star of the pair below the Omega Nebula. The other is the hypergiant HD 168607.

The most notable characteristic of HD 168625 is the presence of a nebula surrounding it that was discovered in 1994[15] and that has been studied with the help of several instruments and observatories and telescopes that include among others the Hubble Space Telescope[11] and the VLT.[12]

Said studies show that HD 168625 is actually surrounded by two nebulae: an inner one that has an elliptical shape and a very complex structure that includes arcs and filaments,[11] and a much larger outer one discovered with the help of the Spitzer Space Telescope that has a bipolar shape and that looks like a clone of the one surrounding Sanduleak -69° 202, the progenitor of the supernova 1987A in the Large Magellanic Cloud.[16] This suggests Sanduleak -69° 202 was also a luminous blue variable as well as the possibility of HD 168625 exploding as a Type II supernova in the near future.[16]

References

  1. ^ a b c d Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  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. ^ a b c Mahy, L.; Hutsemékers, D.; Royer, P.; Waelkens, C. (2016). "Tracing back the evolution of the candidate LBV HD168625". Astronomy & Astrophysics. 594: A94. arXiv:1608.01087. Bibcode:2016A&A...594A..94M. doi:10.1051/0004-6361/201628584. S2CID 119243390.
  5. ^ a b 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.
  6. ^ Sterken, C.; Arentoft, T.; Duerbeck, H. W.; Brogt, E. (1999). "Light variations of the blue hypergiants HD 168607 and HD 168625 (1973-1999)". Astronomy and Astrophysics. 349: 532. Bibcode:1999A&A...349..532S.
  7. ^ 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): 889–896. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID 119323941.
  8. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  9. ^ 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. S2CID 122348932.
  10. ^ a b Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics. 538: A47. arXiv:1111.6375. Bibcode:2012A&A...538A..47N. doi:10.1051/0004-6361/201118040. S2CID 43688343. A47.
  11. ^ a b c Pasquali, A.; Nota, A.; Smith, L.J.; Akiyama, S.; Messineo, M.; Clampin, M. (2002). "Multiwavelength Study of the Nebula Associated with the Galactic LBV Candidate HD 168625". The Astronomical Journal. 124 (3): 1625–1635. arXiv:astro-ph/0207613. Bibcode:2002AJ....124.1625P. doi:10.1086/341820. S2CID 118968760.
  12. ^ a b Umana, G.; Buemi, C.S.; Trigilio, C.; Leto, P.; Hora, J.L. (2010). "Spitzer, Very Large Telescope, and Very Large Array Observations of the Galactic Luminous Blue Variable Candidate HD 168625". The Astrophysical Journal. 718 (2): 1036–1045. Bibcode:2010ApJ...718.1036U. doi:10.1088/0004-637X/718/2/1036.
  13. ^ Martayan, C.; Lobel, A.; Baade, D.; Blomme, R.; Frémat, Y.; Lebouquin, J.-B.; Selman, F.; Girard, J.; Mérand, A.; Montagnier, G.; Patru, F.; Mawet, D.; Martins, F.; Rivinius, Th.; Štefl, S.; Zorec, J.; Semaan, T.; Mehner, A.; Kervella, P.; Sana, H.; Schödel, R. (2012). "On the Binarity of LBV Stars". ASP Conference Proceedings. 464: 293. Bibcode:2012ASPC..464..293M.
  14. ^ Martayan, C.; Lobel, A.; Baade, D.; Mehner, A.; Rivinius, T.; Boffin, Henry M. J.; Ronny, B.; Girard, J.; Mérand, A.; Montagnier, G.; Patru, F.; Mawet, D.; Martins, F.; Rivinius, Th.; Štefl, S.; Zorec, J.; Semaan, T.; Mehner, A.; Kervella, P.; Sana, H.; Schödel, R. (2016). "Luminous blue variables: An imaging perspective on their binarity and near environment" (PDF). Astronomy & Astrophysics. 587: A115. arXiv:1601.03542. Bibcode:2016A&A...587A.115M. doi:10.1051/0004-6361/201526578. S2CID 1755296. A115.
  15. ^ 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.
  16. ^ a b Smith, Nathan (2007). "Discovery of a Nearby Twin of SN 1987A's Nebula around the Luminous Blue Variable HD 168625: Was Sk -69 202 an LBV?". The Astronomical Journal. 133 (3): 1034–1040. arXiv:astro-ph/0611544. Bibcode:2007AJ....133.1034S. doi:10.1086/510838. S2CID 17598600.
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=HD_168625&oldid=998512116"