PV Telescopii

HD 168476

Observation data Epoch J2000      Equinox J2000
Constellation	Telescopium
Right ascension	18^h 23^m 14.66390^s[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
Distance	8,000[6] pc
Absolute magnitude (MV)	−4.4[7]
Details
Mass	0.94[6] M☉
Radius	33.9[6] R☉
Luminosity	25,000[6] L☉
Surface gravity (log g)	1.35[6] cgs
Temperature	12,425[6] K
Metallicity	-0.15[8]
Other designations
PV Telescopii, PV Tel, HD 168476, HIP 90099, CD−56°7300, 2MASS J18231466-5637441
Database references
SIMBAD	data

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.

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

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]

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. 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. 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.