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MY Apodis - Wikipedia

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MY Apodis
Observation data Epoch J2000 Equinox J2000
A light curve for MY Apodis, plotted from TESS data.^[1] Approximately 400 raw data points were averaged to produce each plotted point.
Constellation	Apus
Right ascension	14^h 33^m 07.636^s^[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 (R_v)	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 (M_V)	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

^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 26 August 2024.
^ ^a ^b ^c 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.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ 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.
^ ^a ^b 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.
^ ^a ^b 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.
^ ^a ^b ^c ^d 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.
^ ^a ^b ^c 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.
^ ^a ^b ^c 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.
^ "MY Aps". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-24.
^ ^a ^b 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.
^ 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.

Constellation of Apus

Stars

Bayer	α β γ δ ε ζ η θ ι κ¹ κ²
Variable	R (not variable) S Z MY NN NO
HR	5240 5279 5306 5327 5389 5520 5547 5555 5628 5757 5786 5955 6135 6357 6373 6635 6646 6731 6751
HD	128294 129899 131664 134606 137366 137388 (Karaka) 141846 152010
Other	Godzilla star

Star
clusters

NGC	6101
Other	IC 4499

Nebulae	Hen 2-131

Galaxies	Sunburst galaxy