Y Centauri

Not to be confused with Upsilon Centauri.

This article is about Y Centauri. For y Centauri, see HD 120987. For γ Centauri, see Gamma Centauri.

Y Centauri

A visual band light curve for Y Centauri, plotted from ASAS data[1]
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Centaurus
Right ascension	14^h 30^m 58.61656^s[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 mas[6]
Distance	730 ± 50 ly (220 ± 10 pc)
Details
Radius	48[6] R☉
Luminosity	330[6] L☉
Surface gravity (log g)	−0.315[7] cgs
Temperature	3,557[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
SIMBAD	data

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. Retrieved 8 December 2021.
2. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
3. Samus, N. N.; Durlevich, O. V.; 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. 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. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
6. 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.
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. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. S2CID 73594365.
8. Chandler, S. C. (1896). "Third catalogue of variable stars". Astronomical Journal. 16: 145. Bibcode:1896AJ.....16..145C. doi:10.1086/102484.
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. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x. S2CID 10505995.
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. arXiv:astro-ph/0212201. Bibcode:2003A&A...399.1167P. doi:10.1051/0004-6361:20021843. S2CID 17844733.
12. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
13. 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. Bibcode:2014ApJS..211...15Y. doi:10.1088/0067-0049/211/1/15. S2CID 73561291.
14. Lewis, B. M. (October 1997). "A renewed search for water maser emission from Mira Variables". The Astrophysical Journal. 114: 1602–1606. arXiv:astro-ph/9706207. Bibcode:1997AJ....114.1602L. doi:10.1086/118591. S2CID 119386147.

Notes