Astronomy:MY Apodis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Apus |
| Right ascension | 14h 33m 07.636s[1] |
| Declination | −81° 20′ 14.13″[1] |
| Apparent magnitude (V) | 13.75[2] |
| Characteristics | |
| Evolutionary stage | Compact star |
| Spectral type | DA4.1[2] |
| U−B color index | −0.530 |
| B−V color index | 0.25 |
| Variable type | ZZ Cet[2][3] |
| Astrometry | |
| Radial velocity (Rv) | 58.0[4] km/s |
| Proper motion (μ) | RA: −154.665[1] mas/yr Dec.: −389.971[1] mas/yr |
| Parallax (π) | 47.7874 ± 0.0295 mas |
| Distance | 68.25 ± 0.04 ly (20.93 ± 0.01 pc) |
| Absolute magnitude (MV) | 11.86[2] |
| Details | |
| Mass | 0.705±0.023[5] M☉ |
| Radius | 0.011±0.001[5] R☉ |
| Luminosity | 0.00347[6] L☉ |
| Surface gravity (log g) | 8.17±0.04[2] cgs |
| Temperature | 12,330±182[2] K |
| Rotation | 13 h[7] |
| Other designations | |
| Database references | |
| SIMBAD | data |
MY Apodis, also known as L 19-2, GJ 2108, or WD 1425-811, is a single[6] white dwarf star located in the far southern constellation Apus. It is a low-amplitude variable star[9] with an average apparent visual magnitude of 13.75[2] and thus is much too faint to be visible to the naked eye. Based on parallax measurements, this star is located at a distance of 68.3 light-years from the Sun. It is drifting further away with a radial velocity of 58.0[4]
This compact stellar remnant has a class of DA4.1,[2] which indicates a hydrogen-rich outer atmosphere. It is a pulsating white dwarf (ZZ Ceti star) that varies photometrically with an amplitude of 0.05 in visual magnitude.[3] The low-amplitude variability of this ZZ Ceti analog was discovered by James E. Hesser and associates in 1974, who found it showed periods of 192.75±0.1 and 113.77±0.1 seconds.[9] By 2015, ten different pulsation modes had been identified, and it remained stable over four decades of observation.[10]
MY Apodis has 70.5%[5] of the mass of the Sun compressed down into 1.1%[5] of the Sun's radius. It is spinning rapidly with a rotation period of 13 hours.[7] The star is radiating just 0.35%[6] of the luminosity of the Sun at an effective temperature of 12,330 K.[2] Astroseismological models suggest the star has a thin outer hydrogen shell with a mass of 1.0×10−4 M☉, an intermediate helium layer of 1.5 to 2.0×10−2 M☉, and a core of 20% carbon and 80% oxygen that extends out to 60% of the stellar radius.[7]
References
- ↑ 1.0 1.1 1.2 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Gianninas, A. et al. (2011). "A Spectroscopic Survey and Analysis of Bright, Hydrogen-rich White Dwarfs". The Astrophysical Journal 743 (2): 27. doi:10.1088/0004-637X/743/2/138. 138. Bibcode: 2011ApJ...743..138G.
- ↑ 3.0 3.1 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. http://www.sai.msu.su/gcvs/gcvs/. Retrieved 2021-11-25.
- ↑ 4.0 4.1 Wegner, G. (February 1974). "A spectroscopic survey of southern hemisphere white dwarfs - IV. Radial velocities and space motions". Monthly Notices of the Royal Astronomical Society 166 (2): 271–280. doi:10.1093/mnras/166.2.271. Bibcode: 1974MNRAS.166..271W.
- ↑ 5.0 5.1 5.2 5.3 Romero, A. D. et al. (December 2013). "Asteroseismological Study of Massive ZZ Ceti Stars with Fully Evolutionary Models". The Astrophysical Journal 779 (1): 24. doi:10.1088/0004-637X/779/1/58. 58. Bibcode: 2013ApJ...779...58R.
- ↑ 6.0 6.1 6.2 Toonen, S. et al. (June 2017). "The binarity of the local white dwarf population". Astronomy & Astrophysics 602: 23. doi:10.1051/0004-6361/201629978. A16. Bibcode: 2017A&A...602A..16T.
- ↑ 7.0 7.1 7.2 Bradley, P. A. (May 2001). "Asteroseismological Constraints on the Structure of the ZZ Ceti Stars L19-2 and GD 165". The Astrophysical Journal 552 (1): 326–339. doi:10.1086/320454. Bibcode: 2001ApJ...552..326B.
- ↑ "MY Aps". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=MY+Aps.
- ↑ 9.0 9.1 Hesser, J. E. et al. (July 1977). "High-frequency stellar oscillations. XII. L19-2, a low-amplitude ZZ Ceti variable with periods of 193 and 114 seconds". Astrophysical Journal 215: L75–L78. doi:10.1086/182482. Bibcode: 1977ApJ...215L..75H.
- ↑ Sullivan, D. J.; Chote, P. (June 2015). "The Frequency Stability of the Pulsating White Dwarf L19-2". in Dufour, Patrick; Bergeron, Pierre; Fontaine, Gilles. 19th European Workshop on White Dwarfs, Proceedings of a conference held at the Université de Montréal, Montréal, Canada 11-15 August 2014. 493. San Francisco: Astronomical Society of the Pacific. p. 199. Bibcode: 2015ASPC..493..199S.
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