PV Telescopii

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PV Telescopii
PVTelLightCurve.png
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]
Distance 23,000  ly
(7,100+1,400
−2,000 [1]   pc)
Absolute magnitude  (MV)−4.4 [7]
Details
Mass 0.94 [8]   M☉
Radius 27.20+4.09
−7.26 [1]   R☉
Luminosity 24,000+8,600
−9,900 [1]   L☉
Surface gravity (log g)1.60±0.25 [1]   cgs
Temperature 13,750±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
SIMBAD data

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]

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]

Related Research Articles

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Telescopium is a minor constellation in the southern celestial hemisphere, one of twelve named in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is a Latinized form of the Greek word for telescope. Telescopium was later much reduced in size by Francis Baily and Benjamin Gould.

<span class="mw-page-title-main">Upsilon Sagittarii</span> Binary star system in the constellation Sagittarius

Upsilon Sagittarii is a spectroscopic binary star system in the constellation Sagittarius. Upsilon Sagittarii is the prototypical hydrogen-deficient binary (HdB), and one of only four such systems known. The unusual spectrum of hydrogen-deficient binaries has made stellar classification of Upsilon Sagittarii difficult.

<span class="mw-page-title-main">Lambda Telescopii</span> Star in the constellation Telescopus

λ Telescopii, Latinized as Lambda Telescopii, is a solitary, bluish-white hued star located in the southern constellation of Telescopium. It has an apparent magnitude of 4.84, making it readily visible to the naked eye under ideal conditions. Gaia DR3 parallax measurements imply a distance of 490 light years, and it is currently approaching the Solar System with a somewhat constrained heliocentric radial velocity of −2 km/s. At its current distance, the visual magnitude of Lambda Telescopii is diminished by an extinction of 0.25 due to interstellar dust and it has an absolute magnitude of −1.51.

<span class="mw-page-title-main">Iota Telescopii</span> K-type giant; Telescopium

ι Telescopii, Latinized as Iota Telescopii and abbreviated Iota Tel, is a solitary star located in the southern constellation Telescopium. It is faintly visible to the naked eye as an orange-hued star with an apparent visual magnitude of +4.88. The star is located roughly 377 light years distant from the Solar System based on Gaia DR3 parallax measurements and it is receding with a radial velocity of 22.3 km/s. At its current distance, Iota Tel's brightness is diminished by 0.19 magnitudes due to interstellar dust and it has an absolute magnitude of −0.39.

<span class="mw-page-title-main">28 Cancri</span> Binary star in the constellation Cancer

28 Cancri is a star system in the zodiac constellation of Cancer. It is a variable star with the designation CX Cancri, and is close to the lower limit of visibility with the naked eye, having a mean apparent visual magnitude of 6.05. The annual parallax shift seen from Earth's orbit is 8.5 mas, which provides a distance estimate of about 384 light years. It is moving away from the Sun with a radial velocity of around +9 km/s.

<span class="mw-page-title-main">Pi Cassiopeiae</span> Variable star in the constellation Cassiopeia

Pi Cassiopeiae, Latinized from π Cassiopeiae, is a close binary star system in the constellation Cassiopeia. It is visible to the naked eye with an apparent visual magnitude of +4.949. Based upon an annual parallax shift of 18.63 mas as seen from Earth, this system is located about 175 light years from the Sun.

3 Centauri is a triple star system in the southern constellation of Centaurus, located approximately 300 light years from the Sun. It is visible to the naked eye as a faint, blue-white hued star with a combined apparent visual magnitude of 4.32. As of 2017, the two visible components had an angular separation of 7.851″ along a position angle of 106°. The system has the Bayer designation k Centauri; 3 Centauri is the Flamsteed designation. It is a suspected eclipsing binary with a variable star designation V983 Centauri.

<span class="mw-page-title-main">HD 125823</span> Star in the constellation Centaurus

HD 125823, also known as V761 Centauri or a Centauri, is a variable star in the constellation Centaurus. It is a blue-white star that is visible to the naked eye with a mean apparent visual magnitude of +4.41. The distance to this star is approximately 460 light years based on parallax measurements. It is a member of the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association.

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An extreme helium star is a low-mass supergiant that is almost devoid of hydrogen, the most common chemical element of the Universe. Since there are no known conditions where stars devoid of hydrogen can be formed from molecular clouds, it is theorized that they are the product of the mergers of helium-core and carbon-oxygen core white dwarfs.

GJ 3379 is the nearest star in the Orion constellation, located at a distance of 17 light years from the Sun based on parallax. It is a single star with an apparent visual magnitude of +11.31 and an absolute magnitude of +12.71, therefore, the star is not visible with the naked eye. It is positioned in the upper left part of the Orion constellation, to the SSE of Betelgeuse. This star is drifting further away with a radial velocity of +30.0 kilometers per second. In the past, this star had a relatively close encounter with the Solar System. Some 161,000±6,000 years ago, it achieved a minimum distance of 4.08 ± 0.20 ly (1.25 ± 0.06 pc).

<span class="mw-page-title-main">PV Telescopii variable</span>

PV Telescopii variable is a type of variable star that is established in the General Catalogue of Variable Stars with the acronym PVTEL. This class of variables are defined as "helium supergiant Bp stars with weak hydrogen lines and enhanced lines of He and C". That is, the hydrogen spectral lines of these stars are weaker than normal for a star of stellar class B, while the lines of helium and carbon are stronger. They are a type of extreme helium star.

HD 79498 is a primary of the star system located 159 light years away in the constellation Cancer. This G5 main sequence star has an apparent magnitude of 8.0 and is about the same size and mass as the Sun. It has a higher than solar abundance of elements other than hydrogen and helium; what astronomers term a metal-rich star.

<span class="mw-page-title-main">BX Circini</span> Star in the constellation Circinus

BX Circini is a star in the constellation Circinus. Its variability was discovered in 1995, with its apparent magnitude ranging from 12.57 to 12.62 over a period of 2 hours 33 minutes. It is currently classified as a PV Telescopii variable star, but has been put forward as the prototype of a new class of pulsating star—the BX Circini variables—along with the only other known example, V652 Herculis. This class of star is rare, possibly because this is a brief stage of stellar evolution. Its mass has been calculated to be around 40 percent that of the Sun, but the radius is a few times larger than that of the Sun. The average surface temperature is high, and has been measured at 23,390 ± 90 K using optical spectra, but 1750 K cooler if analysing it in both the visual and ultraviolet. The temperature appears to vary by 3450 K.

<span class="mw-page-title-main">PZ Telescopii</span> Star in the constellation Telescopium

PZ Telescopii, also known as HD 174429 or simply PZ Tel, is a young star in the constellation Telescopium. Based on parallax measurements, it is located at a distance of 154 light years from the Sun. The star is drifting closer with a radial velocity of −4 km/s. It is too faint to be visible to the naked eye and is classified as a BY Draconis variable that ranges in apparent visual magnitude from 8.33 down to 8.63 over a period of 22.581 hours. It is one of the closest and hence brightest pre-main-sequence stars to Earth.

<span class="mw-page-title-main">HR 6819</span> Star system in the constellation of Telescopium

HR 6819, also known as HD 167128 or QV Telescopii, is a double star system in the southern constellation of Telescopium. It is in the south-western corner of the constellation, near Pavo to the south and Ara to the west. The system appears as a variable star that is dimly visible to the naked eye with an apparent magnitude that ranges from 5.32 down to 5.39, which is comparable to the maximum brightness of the planet Uranus. It is about 1,120 light years from the Sun, and is drifting farther away at a rate of 9.4 km/s. Due to its location in the sky, it is visible only to observers south of 33°N latitude.

<span class="mw-page-title-main">36 Lyncis</span> Star in the constellation Lynx

36 Lyncis is a solitary variable star located around 620 light years away from the Sun in the northern constellation of Lynx. It has the variable star designation of EI Lyncis, while 36 Lyncis is the Flamsteed designation. This object is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.30. It is moving further away from the Earth with a heliocentric radial velocity of 21 km/s.

<span class="mw-page-title-main">DY Centauri</span> Star in the constellation Centaurus

DY Centauri is a variable star in the constellation Centaurus. From its brightness, it is estimated to be 7000 parsecs (23000 light-years) away from Earth.

<span class="mw-page-title-main">HK Aquarii</span> Star in the constellation Aquarius

HK Aquarii is a single variable star in the equatorial constellation of Aquarius. It is invisible to the naked eye, having an average apparent visual magnitude that fluctuates around 10.99. The star is located at a distance of 81 light years from the Sun based on parallax. The radial velocity is poorly constrained but it appears to be drifting further away at a rate of ~2 km/s.

<span class="mw-page-title-main">PW Telescopii</span> Α2 CVn variable; Telescopium

PW Telescopii, also known as HD 183806 or simply PW Tel, is a solitary variable star located in the southern constellation Telescopium. It has an average apparent magnitude of 5.58, making it faintly visible to the naked eye. Based on parallax measurements from the Gaia satellite, the star is estimated to be 395 light years distant. It appears to be approaching the Solar System with a heliocentric radial velocity of −10 km/s. The value is somewhat constrained, having an uncertainty of 26%. At its current distance, PW Tel's brightness is diminished by 0.05 magnitudes due to interstellar dust.

References

  1. 1 2 3 4 5 6 7 8 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. 1 2 3 4 5 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. 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. Bibcode:2002yCat.2237....0D.
  4. 1 2 3 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. 1 2 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. 1 2 3 4 5 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. 1 2 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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