Astronomy:HD 213637

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Short description: Star in the constellation Aquarius
HD 213637
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  22h 33m 12.325s[1]
Declination −20° 02′ 21.88″[1]
Apparent magnitude (V) 9.58[2]
Characteristics
Evolutionary stage main sequence[1]
Spectral type A(pEuSrCr)[3] or F1 Eu Sr Cr[4]
B−V color index 0.476[2]
Variable type roAp[5] (α2 CVn[6])
Astrometry
Radial velocity (Rv)5.261±0.0013[7] km/s
Proper motion (μ) RA: 4.685[1] mas/yr
Dec.: 12.118[1] mas/yr
Parallax (π)4.7149 ± 0.0188[1] mas
Distance692 ± 3 ly
(212.1 ± 0.8 pc)
Details
Mass1.50±0.05[1] M☉
Radius1.48±0.08[1] R☉
Luminosity5.47+0.09−0.08[1] L☉
Surface gravity (log g)3.86±0.06[1] cgs
Temperature7,030+64−48[1] K
Metallicity [Fe/H]+0.57[8] dex
Rotational velocity (v sin i)3.5±0.5 km/s
Age570+620−370[1] Myr
Other designations
MM Aqr, BD−20°6447, HD 213637[9]
Database references
SIMBADdata

HD 213637 is a solitary[10] variable star in the zodiac constellation of Aquarius. It has the variable star designation MM Aquarii.[11] With an apparent visual magnitude of 9.6,[2] it is too faint to be visible to the naked eye. Based on parallax measurements, this star is located at a distance of approximately 692 light-years (212 pc) from the Earth. It is drifting further away with a line of sight velocity component of 5.3 km/s.[7]

Observations

This was identified as a chemically peculiar star by N. Houk and M. Smith-Moore in 1988. The stellar spectrum indicates strong metallicity and line blocking in the visual band, which are characteristic of rapidly oscillating Ap stars. The rapid p-mode oscillation of this star was discovered in 1997 by P. Martinez and associates. The spectrum of the measured light curve peaks at a pulsation period of 11 minutes.[5][12] Pulsation amplitudes vary based on the element measured.[13]

This roAP star presents a strong surface magnetic field.[8] The strength of the field was measured at 740±141 G,[4] with a surface field of 5.5 kG. The effective temperature is one of the lowest measured for a magnetic chemically peculiar star,[8] including roAp stars.[14][13] Iron peak elemental abundances appear to be at or below solar, while it is overabundant in the elements strontium, yttrium, and zirconium.[8]

HD 213637 is an estimated 570 million years old, with 1.5 times the mass and 1.48 times the radius of the Sun. It is radiating 5.5 times the Sun's luminosity from its photosphere at an effective temperature of 7,030 K.[1] The star appears to be rotating slowly with a projected rotational velocity of 3.5±0.5 km/s. Evolutionary models suggest this star is near or past the end of its time on the main sequence.[8]

See also

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940.  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Munari, U. et al. (2014), "APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings", The Astronomical Journal 148 (5): 81, doi:10.1088/0004-6256/148/5/81, Bibcode: 2014AJ....148...81M. 
  3. ↑ Houk, Nancy; Smith-Moore, M. (1978), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1988mcts.book.....H. 
  4. ↑ 4.0 4.1 Hubrig, S. et al. (February 2004), "New measurements of magnetic fields of roAp stars with FORS 1 at the VLT", Astronomy and Astrophysics 415: 685–689, doi:10.1051/0004-6361:20031486, Bibcode: 2004A&A...415..685H. 
  5. ↑ 5.0 5.1 Martinez, P. et al. (August 1997), "HD 213637 is a Rapidly Oscillating ap Star", Information Bulletin on Variable Stars 4507: 1, Bibcode: 1997IBVS.4507....1M. 
  6. ↑ 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. 
  7. ↑ 7.0 7.1 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.  [http://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20DR2%20 2401638960512043264 Gaia DR2 record for this source] at VizieR.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Kochukhov, O. (June 2003), "Atmospheric parameters and chemical composition of the ultra-cool roAp star HD 213637", Astronomy and Astrophysics 404: 669–676, doi:10.1051/0004-6361:20030506, Bibcode: 2003A&A...404..669K. 
  9. ↑ "HD 213637". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+213637. 
  10. ↑ Schöller, M. et al. (September 2012), "Multiplicity of rapidly oscillating Ap stars", Astronomy & Astrophysics 545: id. A38, doi:10.1051/0004-6361/201118538, Bibcode: 2012A&A...545A..38S. 
  11. ↑ Kazarovets, E. V. et al. (March 2000), "The 75th Name-List of Variable Stars", Information Bulletin on Variable Stars 4870: 1, Bibcode: 2000IBVS.4870....1K. 
  12. ↑ Martinez, Peter et al. (June 1998), "Discovery of p-mode oscillations in the AP star HD 213637", Astronomy and Astrophysics 334: 606–608, Bibcode: 1998A&A...334..606M. 
  13. ↑ 13.0 13.1 13.2 Elkin, V. G. et al. (February 2015), "Time resolved spectroscopy of the cool Ap star HD 213637*", Monthly Notices of the Royal Astronomical Society 446 (4): 4126–4131, doi:10.1093/mnras/stu2406, Bibcode: 2015MNRAS.446.4126E. 
  14. ↑ Théado, S. et al. (January 2009), "New light on the driving mechanism in roAp stars. I. Effects of metallicity", Astronomy and Astrophysics 493 (1): 159–174, doi:10.1051/0004-6361:200810494, Bibcode: 2009A&A...493..159T. 



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