MY Apodis

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MY Apodis
MYApsLightCurve.png
A light curve for MY Apodis, plotted from TESS data. [1] Approximately 400 raw data points were averaged to produce each plotted point.
Observation data
Epoch J2000       Equinox J2000
Constellation Apus
Right ascension 14h 33m 07.636s [2]
Declination −81° 20′ 14.13″ [2]
Apparent magnitude  (V)13.75 [3]
Characteristics
Evolutionary stage Compact star
Spectral type DA4.1 [3]
U−B color index −0.530
B−V color index 0.25
Variable type ZZ Cet [3] [4]
Astrometry
Radial velocity (Rv)58.0 [5] km/s
Proper motion (μ)RA: −154.665 mas/yr [2]
Dec.: −389.971 mas/yr [2]
Parallax (π)47.7874±0.0295  mas
Distance 68.25 ± 0.04  ly
(20.93 ± 0.01  pc)
Absolute magnitude  (MV)11.86 [3]
Details
Mass 0.705±0.023 [6]   M☉
Radius 0.011±0.001 [6]   R☉
Luminosity 0.00347 [7]   L☉
Surface gravity (log g)8.17±0.04 [3]   cgs
Temperature 12,330±182 [3]   K
Rotation 13 h [8]
Other designations
MY Aps, GJ 2108, L 19-2, LTT 5712, WD 1425-81, 1425-811 [9]
Database references
SIMBAD data

MY Apodis, also known as L 19-2, GJ 2108, or WD 1425-811, is a single [7] white dwarf star located in the far southern constellation Apus. It is a low-amplitude variable star [10] with an average apparent visual magnitude of 13.75 [3] 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 [5]

This compact stellar remnant has a class of DA4.1, [3] 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. [4] 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. [10] By 2015, ten different pulsation modes had been identified, and it remained stable over four decades of observation. [11]

MY Apodis has 70.5% [6] of the mass of the Sun compressed down into 1.1% [6] of the Sun's radius. It is spinning rapidly with a rotation period of 13 hours. [8] The star is radiating just 0.35% [7] of the luminosity of the Sun at an effective temperature of 12,330 K. [3] 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. [8]

References

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 26 August 2024.
  2. 1 2 3 4 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 4 5 6 7 8 9 Gianninas, A.; et al. (2011). "A Spectroscopic Survey and Analysis of Bright, Hydrogen-rich White Dwarfs". The Astrophysical Journal. 743 (2): 27. arXiv: 1109.3171 . Bibcode:2011ApJ...743..138G. doi:10.1088/0004-637X/743/2/138. S2CID   119210906. 138.
  4. 1 2 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   255195566 . Retrieved 2021-11-25.
  5. 1 2 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. Bibcode:1974MNRAS.166..271W. doi: 10.1093/mnras/166.2.271 .
  6. 1 2 3 4 Romero, A. D.; et al. (December 2013). "Asteroseismological Study of Massive ZZ Ceti Stars with Fully Evolutionary Models". The Astrophysical Journal. 779 (1): 24. arXiv: 1310.4137 . Bibcode:2013ApJ...779...58R. doi:10.1088/0004-637X/779/1/58. S2CID   53707228. 58.
  7. 1 2 3 Toonen, S.; et al. (June 2017). "The binarity of the local white dwarf population". Astronomy & Astrophysics. 602: 23. arXiv: 1703.06893 . Bibcode:2017A&A...602A..16T. doi:10.1051/0004-6361/201629978. S2CID   12367523. A16.
  8. 1 2 3 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. Bibcode:2001ApJ...552..326B. doi: 10.1086/320454 . S2CID   121370579.
  9. ↑ "MY Aps". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2021-11-24.
  10. 1 2 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. Bibcode:1977ApJ...215L..75H. doi:10.1086/182482.
  11. ↑ Sullivan, D. J.; Chote, P. (June 2015). Dufour, Patrick; Bergeron, Pierre; Fontaine, Gilles (eds.). The Frequency Stability of the Pulsating White Dwarf L19-2. 19th European Workshop on White Dwarfs, Proceedings of a conference held at the Université de Montréal, Montréal, Canada 11-15 August 2014. ASP Conference Series. Vol. 493. San Francisco: Astronomical Society of the Pacific. p. 199. Bibcode:2015ASPC..493..199S.
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