HD 168607

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HD 168607
The star formation region Messier 17.jpg
HD 168607 is the right star of the pair below the Omega Nebula. The other is the hypergiant HD 168625.
Observation data
Epoch J2000       Equinox J2000
Constellation Sagittarius
Right ascension 18h 21m 14.889s [1]
Declination −16° 22′ 31.76″ [1]
Apparent magnitude  (V)8.12 - 8.29 [2]
Characteristics
Spectral type B9Ia+ [3]
U−B color index 0.41 [4]
B−V color index 1.54 [4]
J−K color index 1.06 [4]
Variable type LBV [5]
Astrometry
Radial velocity (Rv)−30 [6]  km/s
Proper motion (μ)RA: 0.563  mas/yr
Dec.: −1.468 [7]   mas/yr
Parallax (π)0.6438 ± 0.0603  mas [7]
Distance 5,100 ± 500  ly
(1,600 ± 100  pc)
Absolute magnitude  (MV)−8.4 [8]
Details
Radius 187 [8]   R☉
Luminosity 240,000 [8]   L☉
Surface gravity (log g)1.0 [8]   cgs
Temperature 9,300 [8]   K
Other designations
V4029  Sgr, HD  168607, BD−16°4829, SAO 161374, HIP 89956, AAVSO  1815-16
Database references
SIMBAD data

HD 168607 (V4029 Sagittarii) 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

A visual band light curve light curve for V4029 Sagittarii, plotted from ASAS data V4029SgrLightCurve.png
A visual band light curve light curve for V4029 Sagittarii, plotted from ASAS data

HD 168607 was estimated to be about as far away as is the Omega Nebula (2.2 kiloparsecs, 7,200 light years, from the Sun) and no respective measurements have been found that discount physical association with HD 168625. [10] Assuming this distance is correct, this star [11] is 240,000 times brighter than the Sun with a surface temperature of 9,300  K . [11] The Gaia Data Release 2 parallax of 0.6438±0.0603  mas implies a closer distance of about 1,500  pc . [12]

The apparent magnitude of this star or star system was observed to vary by 0.25 to 0.30 magnitudes with a period of 64 days when it was first identified as an α Cygni variable. [13] Unlike its neighbour HD 168625, no nebula has been found around this star. [14] It is classified in the General Catalogue of Variable Stars as a luminous blue variable or S Doradus variable with the variable star designation V4029 Sagittarii and a maximum and minimum visual magnitude of 8.12 and 8.29 respectively. [2] Although it is suspected of being in, or about to enter, an S Doradus phase, no outbursts have been observed. [13] A magnitude variation between 8.05 and 8.41 is reported from a broader range of observations. [15]

HD 168607 is thought to have had a mass between 25 and 30  M☉ when it first formed on the main sequence, but now much less. [13] Analysis of its period and photospheric abundances suggest that it has evolved through a red supergiant stage and has now expelled its outer atmosphere and increased its temperature again. [16]

Related Research Articles

<span class="mw-page-title-main">S Doradus</span> Star in the Large Magellanic Cloud

S Doradus is one of the brightest stars in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way, located roughly 160,000 light-years away. The star is a luminous blue variable, and one of the most luminous stars known, having a luminosity varying widely above and below 1,000,000 times the luminosity of the Sun, although it is too far away to be seen with the naked eye.

<span class="mw-page-title-main">Luminous blue variable</span> Type of star that is luminous, blue, and variable in brightness

Luminous blue variables (LBVs) are massive evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables after S Doradus, one of the brightest stars of the Large Magellanic Cloud. They are considered to be rare.

<span class="mw-page-title-main">P Cygni</span> Variable star in the constellation Cygnus

P Cygni is a variable star in the constellation Cygnus. The designation "P" was originally assigned by Johann Bayer in Uranometria as a nova. Located about 5,300 light-years from Earth, it is a hypergiant luminous blue variable (LBV) star of spectral type B1-2 Ia-0ep that is one of the most luminous stars in the Milky Way.

<span class="mw-page-title-main">Yellow hypergiant</span> Class of massive star with a spectral type of A to K

A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually luminous stars, with absolute magnitude (MV) around −9, but also one of the rarest, with just 20 known in the Milky Way and six of those in just a single cluster. They are sometimes referred to as cool hypergiants in comparison with O- and B-type stars, and sometimes as warm hypergiants in comparison with red supergiants.

<span class="mw-page-title-main">AG Carinae</span> Luminous variable star in the constellation Carina

AG Carinae is a star in the constellation Carina. It is classified as a luminous blue variable (LBV) and is one of the most luminous stars in the Milky Way. The great distance and intervening dust mean that the star is not usually visible to the naked eye; its apparent brightness varies erratically between magnitude 5.7 and 9.0.

<span class="mw-page-title-main">HD 37974</span> Star in the constellation Dorado

HD 37974 a variable B[e] hypergiant in the Large Magellanic Cloud. It is surrounded by an unexpected dust disk.

<span class="mw-page-title-main">HR Carinae</span> Star in the constellation Carina

HR Carinae is a luminous blue variable star located in the constellation Carina. It is surrounded by a vast nebula of ejected nuclear-processed material because this star has a multiple shell expanding atmosphere. This star is among the most luminous stars in the Milky Way. It has very broad emission wings on the Balmer lines, reminiscent from the broad lines observed in the spectra of O and Wolf–Rayet stars. A distance of 5 kpc and a bolometric magnitude of −9.4 put HR Car among the most luminous stars of the galaxy.

<span class="mw-page-title-main">Hypergiant</span> Rare star with tremendous luminosity and high rates of mass loss by stellar winds

A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term hypergiant is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications, except for specific well-defined groups such as the yellow hypergiants, RSG (red supergiants), or blue B(e) supergiants with emission spectra. More commonly, hypergiants are classed as Ia-0 or Ia+, but red supergiants are rarely assigned these spectral classifications. Astronomers are interested in these stars because they relate to understanding stellar evolution, especially star formation, stability, and their expected demise as supernovae.

Zeta<sup>1</sup> Scorpii Star in the constellation Scorpius.

Zeta1 Scorpii is a B-type hypergiant star in the constellation of Scorpius. It has an apparent visual magnitude which varies between 4.66 and 4.86. It is a member of the Scorpius OB1 association, and the open star cluster NGC 6231, also known as the "Northern jewel box" cluster. Around 36 times as massive as the Sun, it is also one of the most luminous stars known in the Galaxy, with an estimated bolometric luminosity of around 850,000 times that of the Sun and a radius 103 times that of the Sun.

<span class="mw-page-title-main">V4381 Sagittarii</span> Star in the constellation Sagittarius

V4381 Sagittarii is a variable star in the constellation Sagittarius. A white supergiant of spectral type A2/A3Iab, it is an Alpha Cygni variable that varies between apparent photographic magnitudes 6.57 and 6.62. Its visual apparent magnitude is about 6.54.

<span class="mw-page-title-main">HD 33579</span> Star in the constellation Dorado

HD 33579 is a white/yellow hypergiant and one of the brightest stars in the Large Magellanic Cloud (LMC). It is a suspected variable star.

<span class="mw-page-title-main">HD 168625</span> Star in the constellation Sagittarius

HD 168625 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 HD 168607 and is located to the south-east of M17, the Omega Nebula.

<span class="mw-page-title-main">HD 160529</span> Luminous blue variable star in the constellation Scorpius

HD 160529 is a luminous blue variable (LBV) star located in the constellation of Scorpius. With an apparent magnitude of around +6.8 cannot be seen with the naked eye except under very favourable conditions, but it is easy to see with binoculars or amateur telescopes.

<span class="mw-page-title-main">HD 50064</span> Star in the constellation Monoceros

HD 50064 is a blue supergiant located in the constellation of Monoceros, easy to see with small telescopes.

<span class="mw-page-title-main">AS 314</span> Protoplanetary nebula in the constellation Scutum

AS 314, also known as V452 Scuti, is a protoplanetary nebula once believed to be a white hypergiant star or luminous blue variable located in the constellation of Scutum. It has an apparent magnitude of 9.85 and can be seen with small telescopes.

<span class="mw-page-title-main">HD 316285</span> Star in the constellation Sagittarius

HDE 316285 is a blue supergiant star in the constellation Sagittarius. It is a candidate luminous blue variable and lies about 6,000 light years away in the direction of the Galactic Center.

<span class="mw-page-title-main">R71 (star)</span> Star in the Large Magellanic Cloud

R71 is a star in the Large Magellanic Cloud (LMC) in the constellation Mensa. It is classified as a luminous blue variable and is one of the most luminous stars in the LMC. It lies three arc-minutes southwest of the naked-eye star β Mensae.

<span class="mw-page-title-main">Westerlund 1-243</span> Luminous blue variable star undergoing an eruptive phase in Westerlund 1

Westerlund 1-243 or Wd 1-243 is a luminous blue variable (LBV) star undergoing an eruptive phase located within the outskirts of the super star cluster Westerlund 1. Located about 13,400 ly (4,100 pc) from Earth, it has a luminosity of 0.73 million L☉ making it one of the most luminous stars known.

<span class="mw-page-title-main">V1936 Aquilae</span> Blue supergiant star in the constellation Aquila

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<span class="mw-page-title-main">B324</span> Star in the Triangulum Galaxy

B324 is a yellow hypergiant in the Triangulum Galaxy, located near the giant H II region IC 142 around 2.7 million light years away. It is the brightest star in the Triangulum Galaxy in terms of apparent magnitude.

References

  1. 1 2 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. 1 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: B/gcvs. 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" (PDF). Astronomy and Astrophysics. 397 (3): 1035–1042. Bibcode:2003A&A...397.1035C. doi: 10.1051/0004-6361:20021430 .
  4. 1 2 3 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.
  5. ↑ 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.
  6. ↑ 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: 0705.0878 . Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID   119323941.
  7. 1 2 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.
  8. 1 2 3 4 5 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.
  9. ↑ "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 8 December 2021.
  10. ↑ 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.
  11. 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 .
  12. ↑ Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Mantelet, G.; Andrae, R. (2018). "Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2". The Astronomical Journal. 156 (2): 58. arXiv: 1804.10121 . Bibcode:2018AJ....156...58B. doi: 10.3847/1538-3881/aacb21 . S2CID   119289017.
  13. 1 2 3 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.
  14. ↑ 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.
  15. ↑ "V4029 Sgr". International Variable Star Index. Retrieved 2021-01-05.
  16. ↑ Saio, Hideyuki; Georgy, Cyril; Meynet, Georges (2013). "Evolution of blue supergiants and α Cygni variables: Puzzling CNO surface abundances". Monthly Notices of the Royal Astronomical Society. 433 (2): 1246–1257. arXiv: 1305.2474 . Bibcode:2013MNRAS.433.1246S. doi:10.1093/mnras/stt796. S2CID   119295289.
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