Astronomy:Y Centauri

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Short description: Variable star in the constellation Centaurus
Not to be confused with Upsilon Centauri.
Y Centauri
YCenLightCurve.png
A visual band light curve for Y Centauri, plotted from ASAS data[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Centaurus
Right ascension  14h 30m 58.61656s[2]
Declination −30° 05′ 51.8706″[2]
Apparent magnitude (V) 8.0 - 9.1[3]
Characteristics
Spectral type M4e - M7[3]
U−B color index +0.72[4]
B−V color index +1.44[4]
Variable type SRb[3]
Astrometry
Radial velocity (Rv)−6.00[5] km/s
Proper motion (μ) RA: −38.874[6] mas/yr
Dec.: −25.867[6] mas/yr
Parallax (π)4.4510 ± 0.2738[6] mas
Distance730 ± 50 ly
(220 ± 10 pc)
Details
Radius48[6] R☉
Luminosity330[6] L☉
Surface gravity (log g)−0.315[7] cgs
Temperature3,557[6] K
Other designations
Y Cen, HD 127233, BD−29°11116, HIP 70969, SAO 182618, GC 19563, IRAS 14280-2952, AAVSO 1425-29
Database references
SIMBADdata

Y Centauri or Y Cen (HD 127233, HIP 70969) is a semiregular variable star in the constellation of Centaurus.

The variability in the star was discovered by Williamina Fleming in 1895 and published in the Third Catalogue of Variable Stars. The photographic magnitude range was given as 7.7 - 8.8, but the variability was described as "somewhat doubtful".[8] It was later given the designation HV 52 in the Harvard Catalogue of Variable Stars.[9] The General Catalogue of Variable Stars lists it as a semiregular variable star with a period of 180 days and a visual magnitude range of 8.0 - 9.1.[3] A study of Hipparcos satellite photometry found a small amplitude range of 0.2 magnitudes at a visual magnitude of 8.53.[10]

The distance of the star is poorly known. The revised Hipparcos annual parallax of 3.50 mas gives a distance of 900 light years.[2] A study taking into account the variability of the star found a parallax of 5.57 mas, corresponding to a distance of 585 light years.[11] Both estimates have a margin of error over 20%. The Gaia Data Release 2 parallax lies between these two values and appears more accurate with a margin of error around 5%, but with a large value for astrometric noise.[6] Gaia EDR3 does not list a parallax for this star.[12]

Y Centauri is an asymptotic giant branch[13] star 330 times as luminous as the sun. Its spectral type varies between M4 and M7 as it pulsates.[3]

The star has been observed to produce 22 GHz water maser emission,[14] although later searches did not find any maser emission.[13]

References

  1. ↑ "ASAS All Star Catalogue". The All Sky Automated Survey. http://www.astrouw.edu.pl/asas/?page=aasc. 
  2. ↑ 2.0 2.1 2.2 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Samus, N. N. et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S 1: 02025. Bibcode: 2009yCat....102025S. 
  4. ↑ 4.0 4.1 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237: 0. Bibcode: 2002yCat.2237....0D. 
  5. ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 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.  Gaia DR2 record for this source at VizieR.
  7. ↑ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society 471 (1): 770. doi:10.1093/mnras/stx1433. Bibcode: 2017MNRAS.471..770M. 
  8. ↑ Chandler, S. C. (1896). "Third catalogue of variable stars". Astronomical Journal 16: 145. doi:10.1086/102484. Bibcode: 1896AJ.....16..145C. 
  9. ↑ Pickering, Edward Charles (1905). "Second supplement to Catalogue of Variable Stars". Annals of Harvard College Observatory 53: 143–153. Bibcode: 1905AnHar..53..143P. 
  10. ↑ Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society 331 (1): 45–59. doi:10.1046/j.1365-8711.2002.05150.x. Bibcode: 2002MNRAS.331...45K. 
  11. ↑ Pourbaix, D.; Platais, I.; Detournay, S.; Jorissen, A.; Knapp, G.; Makarov, V. V. (2003). "How many Hipparcos Variability-Induced Movers are genuine binaries?". Astronomy and Astrophysics 399 (3): 1167–1176. doi:10.1051/0004-6361:20021843. Bibcode: 2003A&A...399.1167P. 
  12. ↑ Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  13. ↑ 13.0 13.1 Yoon, Dong-Hwan; Cho, Se-Hyung; Kim, Jaeheon; Yun, Young joo; Park, Yong-Sun (2014). "SiO and H2O Maser Survey toward Post-asymptotic Giant Branch and Asymptotic Giant Branch Stars". The Astrophysical Journal Supplement 211 (1): 15. doi:10.1088/0067-0049/211/1/15. Bibcode: 2014ApJS..211...15Y. 
  14. ↑ Lewis, B. M. (October 1997). "A renewed search for water maser emission from Mira Variables". The Astrophysical Journal 114: 1602–1606. doi:10.1086/118591. Bibcode: 1997AJ....114.1602L. 

Notes



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