PV Telescopii

PV Telescopii (also known as HD 168476) is a class B-type (blue) supergiant extreme helium star in the constellation Telescopium. It is also the prototype of variable stars called PV Telescopii variables.

HD 168476
Observation data
Epoch J2000      Equinox J2000
Constellation Telescopium
Right ascension  18h 23m 14.66390s[1]
Declination −56° 37′ 44.1512″[1]
Apparent magnitude (V) 9.30[2] (9.24 - 9.40[3])
Characteristics
Spectral type B5p[4]
U−B color index −0.60[2]
B−V color index −0.10[2]
Variable type PV Tel[3]
Astrometry
Radial velocity (Rv)-169[5] km/s
Proper motion (μ) RA: 0.38[1] mas/yr
Dec.: -9.29[1] mas/yr
Parallax (π)0.43 ± 1.12[1] mas
Distance8,000[6] pc
Absolute magnitude (MV)−4.4[7]
Details
Mass0.94[6] M☉
Radius33.9[6] R☉
Luminosity25,000[6] L☉
Surface gravity (log g)1.35[6] cgs
Temperature12,425[6] K
Metallicity-0.15[8]
Other designations
PV Telescopii, PV Tel, HD 168476, HIP 90099, CD−56°7300, 2MASS J18231466-5637441
Database references
SIMBADdata

Properties

PV Telescopii shows radial velocity changes thought to be due to radial pulsations caused by a strange mode instability[6] It appears as a star of magnitude 9.3. Despite a mass thought to be less than the sun, it is actually around 25,000 more luminous. The spectrum shows a strong hydrogen deficiency and strongly enhanced helium and carbon lines.[9]

PV Telescopii variable
Main article: PV Telescopii variable

PV Telescopii variables are helium supergiants which vary somewhat irregularly over about 0.1 magnitude on a time-scale of hours to days. PV Telescopii is an example with variations over a few days, 8–10 days being typically quoted. It may be a late thermal pulse post-AGB star or the result of a white dwarf merger.[6][10]

gollark: It'll be sent as an incident report, though.
gollark: It won't accept that.
gollark: What question, the semiprime question?
gollark: I actually originally brought up the potatOS thing to illustrate that people are often stupid, so...
gollark: It even has a privacy policy!

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. 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. Bibcode:2002yCat.2237....0D.
  3. 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.
  4. Walker, H. J.; Hill, P. W. (1985). "Radial velocities for the hydrogen-deficient star HD 168476, several helium-strong and helium-weak stars". Astronomy and Astrophysics Supplement Series. 61: 303. Bibcode:1985A&AS...61..303W.
  5. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. Jeffery, C. S.; Starling, R. L. C.; Hill, P. W.; Pollacco, D. (2001). "Cyclic and secular variation in the temperatures and radii of extreme helium stars". Monthly Notices of the Royal Astronomical Society. 321: 111. Bibcode:2001MNRAS.321..111J. CiteSeerX 10.1.1.29.1648. doi:10.1046/j.1365-8711.2001.03992.x.
  7. Heber, U.; Schoenberner, D. (1981). "Colours and effective temperatures of extreme helium stars". Astronomy and Astrophysics. 102: 73. Bibcode:1981A&A...102...73H.
  8. Soubiran, C.; Le Campion, J. -F.; Cayrel De Strobel, G.; Caillo, A. (2010). "The PASTEL catalogue of stellar parameters". Astronomy and Astrophysics. 515: A111. arXiv:1004.1069. Bibcode:2010A&A...515A.111S. doi:10.1051/0004-6361/201014247.
  9. Pandey, Gajendra; Lambert, David L. (2011). "Neon and CNO Abundances for Extreme Helium Stars—A Non-LTE Analysis". The Astrophysical Journal. 727 (2): 122. arXiv:1011.5035. Bibcode:2011ApJ...727..122P. doi:10.1088/0004-637X/727/2/122.
  10. Gourgouliatos, K. N.; Jeffery, C. S. (2006). "On the angular momentum evolution of merged white dwarfs". Monthly Notices of the Royal Astronomical Society. 371 (3): 1381. arXiv:astro-ph/0607379. Bibcode:2006MNRAS.371.1381G. doi:10.1111/j.1365-2966.2006.10780.x.
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