HD 213637
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| 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 mas/yr[1] Dec.: 12.118 mas/yr[1] |
| Parallax (π) | 4.7149±0.0188 mas[1] |
| Distance | 692 ± 3 ly (212.1 ± 0.8 pc) |
| Details | |
| Mass | 1.50±0.05[1] M☉ |
| Radius | 1.48±0.08[1] R☉ |
| Luminosity | 5.47+0.09 −0.08[1] L☉ |
| Surface gravity (log g) | 3.86±0.06[1] cgs |
| Temperature | 7,030+64 −48[1] K |
| Metallicity [Fe/H] | +0.57[8] dex |
| Rotational velocity (v sin i) | 3.5±0.5 km/s |
| Age | 570+620 −370[1] Myr |
| Other designations | |
| MM Aqr, BD−20°6447, HD 213637[9] | |
| Database references | |
| SIMBAD | data |
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
- Przybylski's Star, another cool roAP star[13]
References
- ^ a b c d e f g h i j k l Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c 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, arXiv:1408.5476, Bibcode:2014AJ....148...81M, doi:10.1088/0004-6256/148/5/81, hdl:1885/19979, S2CID 56127278.
- ^ Houk, Nancy; Smith-Moore, M. (1978), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
- ^ a b 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, arXiv:astro-ph/0309560, Bibcode:2004A&A...415..685H, doi:10.1051/0004-6361:20031486.
{{citation}}: CS1 maint: year (link) - ^ a b 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.
- ^ 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 125853869.
- ^ a b 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 Kochukhov, O. (June 2003), "Atmospheric parameters and chemical composition of the ultra-cool roAp star HD 213637", Astronomy and Astrophysics, 404: 669–676, Bibcode:2003A&A...404..669K, doi:10.1051/0004-6361:20030506.
- ^ "HD 213637", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2026-03-18.
- ^ Schöller, M.; et al. (September 2012), "Multiplicity of rapidly oscillating Ap stars", Astronomy & Astrophysics, 545, id. A38, arXiv:1208.0480, Bibcode:2012A&A...545A..38S, doi:10.1051/0004-6361/201118538.
- ^ 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.
- ^ 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.
- ^ a b c 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, arXiv:1411.3217, Bibcode:2015MNRAS.446.4126E, doi:10.1093/mnras/stu2406.
- ^ 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, arXiv:0811.3495, Bibcode:2009A&A...493..159T, doi:10.1051/0004-6361:200810494.