MY Apodis

MY Apodis

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
Distance68.25 ± 0.04 ly
(20.93 ± 0.01 pc)
Absolute magnitude (MV)11.86[3]
Details
Mass0.705±0.023[6] M☉
Radius0.011±0.001[6] R☉
Luminosity0.00347[7] L☉
Surface gravity (log g)8.17±0.04[3] cgs
Temperature12,330±182[3] K
Rotation13 h[8]
Other designations
MY Aps, GJ 2108, L 19-2, LTT 5712, WD 1425-81, 1425-811[9]
Database references
SIMBADdata

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]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i Cite error: The named reference Gianninas 2011 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Wegner1974 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Romero_et_al_2013 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Roonen_et_al_2017 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Bradley2001 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Hesser_et_al_1977 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Sullivan_Chote_2015 was invoked but never defined (see the help page).