Astronomy:HR 2501

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Short description: Star in the constellation Canis Major
HR 2501
HPCMaLightCurve.png
Light curves for HP Canis Majoris. The main plot, from Hipparcos data,[1] shows the long-term variability. The inset plot, from TESS data,[2] shows the short timescale variability.
Observation data
Equinox J2000.0]] (ICRS)
Constellation Canis Major
Right ascension  06h 45m 31.18877s[3]
Declination −30° 56′ 56.3297″[3]
Apparent magnitude (V) 5.35 - 5.80[4]
Characteristics
Spectral type B1.5 Vne[5]
U−B color index −0.89[5]
B−V color index −0.19[5]
Variable type γ Cas + λ Eri[6]
Astrometry
Proper motion (μ) RA: −3.284±0.084[3] mas/yr
Dec.: 4.630±0.098[3] mas/yr
Parallax (π)1.6500 ± 0.0895[3] mas
Distance2,000 ± 100 ly
(610 ± 30 pc)
Absolute magnitude (MV)−3.23[7]
Details
Mass9.6[8] M☉
Radius7.5[3] R☉
Luminosity2,067[9] L☉
Surface gravity (log g)3.60[3] cgs
Temperature22,070[10] K
Metallicity [Fe/H]+0.18[3] dex
Rotational velocity (v sin i)135[10] km/s
Age23[8] Myr
Other designations
HP Canis Majoris, HD 49131, HIP 32385, SAO 197177[11]
Database references
SIMBADdata

HR 2501, also known as HD 49131 and HP Canis Majoris, is a star about 2,000 light years from the Earth, in the constellation Canis Major.[3] It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights.[3] It is a variable star, whose brightness varies from magnitude 5.35 to 5.80 on a variety of timescales ranging from hours to hundreds of days.[4][12]

In 1838, John Herschel discovered that HR 2501 is a double star, with a magnitude 8.4 companion 4.9 arc seconds away.[13] The companion is a slightly less massive, cooler, and less luminous B-type main sequence star.[3] It is also a chemically peculiar helium-weak star.[5]

In 1977, Mikolaj Jerzykiewicz and Christiaan Sterken detected slight (0.12 magnitude) variability in the brightness of HR 2501 during their search for beta Cephei variable stars in the southern sky.[14] Christoffel Waelkens et al. confirmed that HR 2501 is variable in 1983, and reported that it varied in brightness on a timescale of weeks to months, with no clear period.[15] In 1986 it was given the variable star designation HP Canis Majoris.[16] In 1998, Anne-Marie Hubert and Michele Floquet examined the Hipparcos data for HR 2501, and found that it exhibited outbursts in which the brightness increased by 0.35 magnitudes, with a rise time of 100 days and a decay time of 400 days.[17]

In 1984, Christopher Corbally found that the spectrum HR 2501 shows Hα, Hβ, Hγ and Hδ emission features, which along with its spectral type makes it a Be star.[5] Jacqueline Coté found that the IRAS data for HR 2501 showed excess (above what would be expected from the star's photosphere) 12 and 25 μ emission. She concluded that this infrared excess could be due to either a circumstellar dust shell located 21 stellar radii from HR 2501, with a temperature of about 585 K, or (more likely) free-free emission from circumstellar gas.[18]

An extensive study of HR 2501, published in 2003 by Fabien Carrier and Gilbert Burki, found that the star exhibits several periodicities. The radial velocity varies by 20.5 km/sec with a period of 19.005±0.0091 hours. They confirm the roughly 500 day photometric period found earlier by Hubert and Floquet, and suggest these outbursts may arise from episodes of matter ejection from the star or disk formation. Finally, they found a low amplitude (0.065 magnitude) brightness oscillation with a period of 11.05 hours. Spectroscopic data were presented by Carrier and Burki which suggest that during the brightness outbursts, "blobs" of ejected matter can be detected moving through a Keplerian disk surrounding the star.[12]

References

  1. ↑ EAS (1997). "The HIPPARCOS and TYCHO catalogues". Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission. ESA SP Series (Noordwijk, Netherlands: ESA Publications Division) 1200. ISBN 9290923997. Bibcode: 1997ESASP1200.....E. https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats. Retrieved 15 October 2022. 
  2. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 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.
  4. ↑ 4.0 4.1 "V918 Sco database entry". Combined General Catalog of Variable Stars. CDS. http://vizier.cds.unistra.fr/viz-bin/VizieR-S?V*%20V918%20Sco. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Corbally, C. J. (August 1984). "Close visual binaries.I.MK classifications". Astrophysical Journal Supplement Series 55: 657–677. doi:10.1086/190973. Bibcode: 1984ApJS...55..657C. https://ui.adsabs.harvard.edu/abs/1984ApJS...55..657C. Retrieved 23 February 2023. 
  6. ↑ "HP CMa". AAVSO. https://www.aavso.org/vsx/index.php?view=detail.top&oid=5369. 
  7. ↑ Melnik, A. M.; Dambis, A. K. (2020). "Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions". Astrophysics and Space Science 365 (7): 112. doi:10.1007/s10509-020-03827-0. Bibcode: 2020Ap&SS.365..112M. 
  8. ↑ 8.0 8.1 Tetzlaff, N. et al. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society 410 (1): 190–200. doi:10.1111/j.1365-2966.2010.17434.x. Bibcode: 2011MNRAS.410..190T. 
  9. ↑ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society 471 (1): 770–791. doi:10.1093/mnras/stx1433. ISSN 0035-8711. Bibcode: 2017MNRAS.471..770M. 
  10. ↑ 10.0 10.1 Zorec, J. et al. (November 2016). "Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity". Astronomy & Astrophysics 595: 26. doi:10.1051/0004-6361/201628760. Bibcode: 2016A&A...595A.132Z. 
  11. ↑ "HD 49131 -- Be Star". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+49131+--+Be+Star. 
  12. ↑ 12.0 12.1 Carrier, F.; Burki, G. (April 2003). "Outbursts in the Be star HR 2501". Astronomy and Astrophysics 401: 271–279. doi:10.1051/0004-6361:20030125. Bibcode: 2003A&A...401..271C. https://www.aanda.org/component/article?access=bibcode&bibcode=&bibcode=2003A%2526A...401..271CFUL. Retrieved 22 February 2023. 
  13. ↑ Worley, C. E.; Douglass, G. G. (November 1997). "The Washington Double Star Catalog (WDS, 1996.0)". Astronomy and Astrophysics Supplement Series 125 (3): 523. doi:10.1051/aas:1997239. Bibcode: 1997A&AS..125..523W. https://aas.aanda.org/articles/aas/abs/1997/15/ds6100/ds6100.html. Retrieved 23 February 2023. 
  14. ↑ Jerzykiewicz, M.; Sterken, C. (1977). "Search for beta Cephei stars south of declination -20 . I. Incidence of light variability among early B giants and subgiants - summer objects". Acta Astron. 27: 365–387. Bibcode: 1977AcA....27..365J. https://ui.adsabs.harvard.edu/abs/1977AcA....27..365J. Retrieved 23 February 2023. 
  15. ↑ Waelkens, C.; Rufener, F.; Burnet, M. (1983). "Photometric variations of some early Be stars". Hvar Observatory Bulletin 7 (1): 125–130. Bibcode: 1983HvaOB...7..125W. https://ui.adsabs.harvard.edu/abs/1983HvaOB...7..125W. Retrieved 23 February 2023. 
  16. ↑ Kholopov, P. N.; Samus, N. N.; Kazarovets, E. V.; Kireeva, N. N. (August 1987). "The 68th Name-List of Variable Stars". Information Bulletin on Variable Stars 3058: 1. Bibcode: 1987IBVS.3058....1K. https://ibvs.konkoly.hu/pub/ibvs/3001/3058.pdf. Retrieved 23 February 2023. 
  17. ↑ Hubert, A. M.; Floquet, M. (July 1998). "Investigation of the variability of bright Be stars using HIPPARCOS photometry". Astronomy and Astrophysics 335: 565–572. Bibcode: 1998A&A...335..565H. https://articles.adsabs.harvard.edu/pdf/1998A%26A...335..565H. Retrieved 23 February 2023. 
  18. ↑ Coté, J. (July 1987). "B and A type stars with unexpectedly large colour excesses at IRAS wavelengths". Astronomy and Astrophysics 181: 77–84. Bibcode: 1987A&A...181...77C. https://ui.adsabs.harvard.edu/abs/1987A&A...181...77C. Retrieved 23 February 2023. 



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