PV Telescopii

PV Telescopii, also known as HD 168476, is a variable star in the southern constellation of Telescopium. It is too dim to be visible to the naked eye, having an apparent visual magnitude that has been measured varying from 9.24 down to 9.40.[4] The star is the prototype of a class of objects called PV Telescopii variables. It is located at an estimated distance of approximately 23 kilolight-years (7.1 kiloparsecs) from the Sun,[1] but is drifting closer with a radial velocity of −169 km/s.[6]

PV Telescopii

A light curve for PV Telescopii, adapted from Jeffery et al. (2020)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Telescopium
Right ascension 18h 23m 14.66203s[2]
Declination −56° 37′ 44.1401″[2]
Apparent magnitude (V) 9.30[3] (9.24 - 9.40)[4]
Characteristics
Spectral type B5p[5]
U−B color index −0.60[3]
B−V color index −0.10[3]
Variable type PV Tel[4]
Astrometry
Radial velocity (Rv)−169[6] km/s
Proper motion (μ) RA: −1.086[2] mas/yr
Dec.: −7.705[2] mas/yr
Parallax (π)0.1162 ± 0.0449 mas[2]
Distance23,000 ly
(7,100+1,400
−2,000[1] pc)
Absolute magnitude (MV)−4.4[7]
Details
Mass0.94[8] M☉
Radius27.20+4.09
−7.26[1] R☉
Luminosity24,000+8,600
−9,900[1] L☉
Surface gravity (log g)1.60±0.25[1] cgs
Temperature13,750±400[1] K
Metallicity [Fe/H]−0.15[9] dex
Other designations
PV Tel, CD−56°7300, HD 168476, HIP 90099, SAO 245434, 2MASS J18231466-5637441, AAVSO 1814-56[10]
Database references
SIMBADdata

This is an extreme helium star that shows a highly-processed atmosphere.[11] It is a blue-white hued B-type supergiant star with a peculiar spectrum that has "weak hydrogen lines and enhanced lines of He and C".[12][13] This object may be a late thermal pulse post-AGB star or the result of a merger of two white dwarf stars.[8][14] The star shows radial velocity changes thought to be due to radial pulsations caused by a strange mode instability.[8] It shows variations over a few days, 8–10 days being typically quoted.[8][14] Despite a mass thought to be less than the sun,[8] it is actually around 24,000 more luminous.[1]

References
  1. Jeffery, C. Simon; et al. (April 2020). "TESS photometry of extreme helium stars PV Tel and V821 Cen". Monthly Notices of the Royal Astronomical Society: Letters. 495 (1): L135–L138. arXiv:2006.00946. Bibcode:2020MNRAS.495L.135J. doi:10.1093/mnrasl/slaa075.
  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.
  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. Bibcode:2002yCat.2237....0D.
  4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869
  5. 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.
  6. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  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. Jeffery, C. S.; et al. (2001). "Cyclic and secular variation in the temperatures and radii of extreme helium stars". Monthly Notices of the Royal Astronomical Society. 321 (1): 111–130. Bibcode:2001MNRAS.321..111J. CiteSeerX 10.1.1.29.1648. doi:10.1046/j.1365-8711.2001.03992.x.
  9. 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. S2CID 118362423.
  10. "PV Tel". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-11-16.
  11. Saio, Hideyuki; Jeffery, C. Simon (June 2002). "Merged binary white dwarf evolution: rapidly accreting carbon-oxygen white dwarfs and the progeny of extreme helium stars". Monthly Notices of the Royal Astronomical Society. 333 (1): 121–132. Bibcode:2002MNRAS.333..121S. doi:10.1046/j.1365-8711.2002.05384.x.
  12. Jeffery, C. Simon (March 2008). "Variable Star Designations for Extreme Helium Stars". Information Bulletin on Variable Stars. 5817: 1. Bibcode:2008IBVS.5817....1J.
  13. 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. S2CID 118621588.
  14. 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): 1381–1389. arXiv:astro-ph/0607379. Bibcode:2006MNRAS.371.1381G. doi:10.1111/j.1365-2966.2006.10780.x. S2CID 10489476.
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