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L 1159-16 is a red dwarf in the northern constellation of Aries. With a normal apparent visual magnitude of 12.3, it is too faint to be seen by the naked eye, although it lies relatively close to the Sun at a distance of about 14.6 light-years. It is a flare star, which means it can suddenly increase in brightness for short periods of time.
Delta Scuti, Latinized from δ Scuti, is a variable star in the southern constellation Scutum. With an apparent visual magnitude that fluctuates around 4.72, it is the fifth-brightest star in this small and otherwise undistinguished constellation. Analysis of the parallax measurements place this star at a distance of about 199 light-years from Earth. It is drifting closer with a radial velocity of −45 km/s.
Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200,000 K in their interiors. These stars are usually hot blue-white stars of spectral class B and should not be confused with Cepheid variables, which are named after Delta Cephei and are luminous supergiant stars.
RV Tauri variables are luminous variable stars that have distinctive light variations with alternating deep and shallow minima.
Tau Virginis is a single star in the zodiac constellation Virgo. With an apparent visual magnitude of 4.28, it is faintly visible to the naked eye. The distance to Tau Virginis, based upon parallax measurements, is approximately 225 light years with a margin of error of ±3 light years.
9 Aurigae is a star system in Auriga (constellation). It has an apparent magnitude of about 5, making it visible to the naked eye in many suburban skies. Parallax estimates made by the Hipparcos spacecraft put it at about 85.7 light-years from the solar system.
RT Aurigae is a yellow supergiant variable star in the constellation Auriga, about 1,500 light years from Earth.
59 Aurigae, often abbreviated as 59 Aur, is a star in the constellation Auriga. Its baseline apparent magnitude is 6.1, meaning it can just barely be seen with the naked eye as a dim, yellow-white hued star. Based on parallax measurements, it is located about 483 light-years away from the Sun.
Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant stars of spectral types B or A. Variations in brightness on the order of 0.1 magnitudes are associated with the pulsations, which often seem irregular, due to beating of multiple pulsation periods. The pulsations typically have periods of several days to several weeks.
HD 84810, also known as l Carinae, is a star in the southern constellation of Carina. Its apparent magnitude varies from about 3.4 to 4.1, making it readily visible to the naked eye and one of the brightest members of Carina. Based upon parallax measurements, it is approximately 1,600 light-years from Earth.
Zeta Cassiopeiae, Latinized from ζ Cassiopeiae, and officially named Fulu, is a variable star in the constellation of Cassiopeia. It has a blue-white hue and is classified as a B-type subgiant with an apparent magnitude of +3.66. Based upon parallax measurements, it is approximately 590 light-years from the Sun.
W Cephei is a spectroscopic binary and variable star located in the constellation Cepheus. It is thought to be a member of the Cep OB1 stellar association at about 8,000 light years. The supergiant primary star, known as W Cephei A, is one of largest known stars and as well as one of most luminous red supergiants.
HL Tau 76 is a variable white dwarf star of the DAV type. It was observed by G. Haro and W. J. Luyten in 1961, and was the first variable white dwarf discovered when, in 1968, Arlo U. Landolt found that it varied in brightness with a period of approximately 749.5 seconds, or 12.5 minutes. Like other DAV white dwarfs, its variability arises from non-radial gravity wave pulsations within itself., § 7. Later observation and analysis has found HL Tau 76 to pulsate in over 40 independent vibrational modes, with periods between 380 seconds and 1390 seconds.
A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmospheres and the spectral type DA; DBV, or V777 Her, stars, with helium-dominated atmospheres and the spectral type DB; and GW Vir stars, with atmospheres dominated by helium, carbon, and oxygen, and the spectral type PG 1159. GW Vir stars may be subdivided into DOV and PNNV stars; they are not, strictly speaking, white dwarfs but pre-white dwarfs which have not yet reached the white dwarf region on the Hertzsprung-Russell diagram. A subtype of DQV stars, with carbon-dominated atmospheres, has also been proposed, and in May 2012, the first extremely low mass variable (ELMV) white dwarf was reported.
A PG 1159 star, often also called a pre-degenerate, is a star with a hydrogen-deficient atmosphere that is in transition between being the central star of a planetary nebula and being a hot white dwarf. These stars are hot, with surface temperatures between 75,000 K and 200,000 K, and are characterized by atmospheres with little hydrogen and absorption lines for helium, carbon and oxygen. Their surface gravity is typically between 104 and 106 meters per second squared. Some PG 1159 stars are still fusing helium., § 2.1.1, 2.1.2, Table 2. The PG 1159 stars are named after their prototype, PG 1159-035. This star, found in the Palomar-Green survey of ultraviolet-excess stellar objects, was the first PG 1159 star discovered.
T Cephei is a Mira variable star in the constellation Cepheus. Located approximately 570 ± 40 light-years distant, it varies between magnitudes 5.2 and 11.3 over a period of around 388 days.
S Coronae Borealis is a Mira variable star in the constellation Corona Borealis. Its apparent magnitude varies between 5.8 and 14.1, with a period of 360 days—just under a year. Within the constellation, it lies to the west of Theta Coronae Borealis, and around 1 degree southeast of the eclipsing binary star U Coronae Borealis.
RX Andromedae is a variable star in the constellation of Andromeda. Although it is classified as a dwarf nova of the Z Camelopardalis (UGZ) type, it has shown low-luminosity periods typical of VY Sculptoris stars. However, for most of the time it varies from an apparent visual magnitude of 15.1 at minimum brightness to a magnitude of 10.2 at maximum brightness, with a period of approximately 13 days.
W Virginis is the prototype W Virginis variable, a subclass of the Cepheid variable stars. It is located in the constellation Virgo, and varies between magnitudes 9.46 and 10.75 over a period of approximately 17 days.
55 Cygni is a blue supergiant star in the constellation Cygnus. It is thought to be a member of the Cygnus OB7 stellar association at about 2,700 light years.
References
- 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.
- ↑ "PG 1159-035". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 11 June 2007.
- 1 2 3 Chen, Y. H. (2019). "Asteroseismology of the DOV star PG 1159-035". Monthly Notices of the Royal Astronomical Society. 488 (2): 2253. arXiv: 1907.01137 . Bibcode:2019MNRAS.488.2253C. doi:10.1093/mnras/stz1813.
- 1 2 Kawaler, Steven D.; Bradley, Paul A. (1994). "Precision asteroseismology of pulsating PG 1159 stars". The Astrophysical Journal. 427: 415. Bibcode:1994ApJ...427..415K. doi:10.1086/174152.
- ↑ Green, R. F.; Schmidt, M.; Liebert, J. (1986). "The Palomar-Green Catalog of Ultraviolet-Excess Stellar Objects". The Astrophysical Journal Supplement Series. 61: 305. Bibcode:1986ApJS...61..305G. doi:10.1086/191115. CDS ID II/207 Archived 2007-02-20 at the Wayback Machine .
- ↑ Jahn, D.; Rauch, T.; Reiff, E.; Werner, K.; Kruk, J. W.; Herwig, F. (2007). "High-resolution ultraviolet spectroscopy of PG 1159-035 with HST and FUSE". Astronomy and Astrophysics. 462 (1): 281. arXiv: astro-ph/0610592 . Bibcode:2007A&A...462..281J. doi:10.1051/0004-6361:20065901. S2CID 17679220.
- ↑ McGraw, J. T.; Starrfield, S. G.; Liebert, J.; Green, R. (1979). "PG 1159-035: A New, Hot, Non-Da Pulsating Degenerate". IAU Colloq. 53: White Dwarfs and Variable Degenerate Stars: 377. Bibcode:1979wdvd.coll..377M.
- ↑ Kholopov, P. N.; Samus, N. N.; Kazarovets, E. V.; Perova, N. B. (1985). "The 67th Name-List of Variable Stars". Information Bulletin on Variable Stars. 2681: 1. Bibcode:1985IBVS.2681....1K.
- ↑ Nagel, T.; Werner, K. (2004). "Detection of non-radial g-mode pulsations in the newly discovered PG 1159 star <ASTROBJ>HE 1429-1209</ASTROBJ>". Astronomy and Astrophysics. 426. arXiv: astro-ph/0409243 . Bibcode:2004A&A...426L..45N. doi:10.1051/0004-6361:200400079. S2CID 9481357.
- ↑ Quirion, P. -O; Fontaine, G.; Brassard, P. (2007). "Mapping the Instability Domains of GW vir Stars in the Effective Temperature-Surface Gravity Diagram". The Astrophysical Journal Supplement Series. 171 (1): 219. Bibcode:2007ApJS..171..219Q. doi:10.1086/513870.
- ↑ Winget, D. E. (1998). "Asteroseismology of white dwarf stars". Journal of Physics: Condensed Matter. 10 (49): 11247–11261. Bibcode:1998JPCM...1011247W. doi:10.1088/0953-8984/10/49/014.
- ↑ Winget, D. E.; et al. (1991). "Asteroseismology of the DOV Star PG 1159-035 with the Whole Earth Telescope". The Astrophysical Journal. 378: 326. Bibcode:1991ApJ...378..326W. doi:10.1086/170434. hdl:10183/108718.
- ↑ Costa, J. E. S.; et al. (2008). "The pulsation modes of the pre-white dwarf PG 1159-035". Astronomy and Astrophysics. 477 (2): 627. arXiv: 0711.2244 . Bibcode:2008A&A...477..627C. doi:10.1051/0004-6361:20053470. S2CID 6762152.