Astronomy:TZ Cassiopeiae

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Short description: Star in the constellation Cassiopeia
TZ Cassiopeiae
Observation data
Equinox J2000.0]] (ICRS)
Constellation Cassiopeia
Right ascension  23h 52m 56.23689s[1]
Declination 61° 00′ 08.3915″[1]
Apparent magnitude (V) 9.18[2] (+8.86 - +10.5[3])
Characteristics
Spectral type M3 Iab[4]
U−B color index +2.43[2]
B−V color index +2.57[2]
Variable type Lc[3]
Astrometry
Radial velocity (Rv)−54.28[5] km/s
Proper motion (μ) RA: −3.865[1] mas/yr
Dec.: −2.145[1] mas/yr
Parallax (π)0.3888 ± 0.0300[1] mas
Distance8,400 ± 600 ly
(2,600 ± 200 pc)
Absolute magnitude (MV)−5.98[6]
Details
Mass4.9[7] M☉
Radius767[8] R☉
Luminosity97,275[9] L☉
Surface gravity (log g)−0.15[7] cgs
Temperature3,597[9] K
Metallicity [Fe/H]+0.15[7] dex
Other designations
BD+60°2634, HIP 117763, SAO 20192, 2MASS J23525623+6100083, AAVSO 2348+60
Database references
SIMBADdata

TZ Cassiopeiae (TZ Cas, HIP 117763, SAO 20912) is a variable star in the constellation Cassiopeia with an apparent magnitude of around +9 to +10. It is approximately 8,400 light-years away from Earth. The star is a red supergiant star with a spectral type of M3 and a temperature around 3,600 K.

A light curve for TZ Cassiopeiae, plotted from Hipparcos data[10]

TZ Cassiopeiae was reported as being variable by Williamina Fleming and published posthumously in 1911.[11] It is a slow irregular variable star with a possible period of 3,100 days.[12] It is over 90,000 times the luminosity of the Sun, and it is 767 times larger than the Sun. It is a member of the Cas OB5 stellar association, together with the nearby red supergiant PZ Cassiopeiae.[13]

The initial mass of TZ Cassiopeiae has been estimated from its position relative to theoretical stellar evolutionary tracks to be around 15 M☉.[14]

TZ Cas is losing mass through a powerful stellar wind at two millionths of a solar mass each year.[15] It is unclear whether this is sufficient to cause the star to lose its atmosphere and become a blue supergiant before the core exhausts its fuel and collapses as a supernova. Either as a red or blue supergiant, or a Wolf–Rayet star, it will inevitably end its life violently in a supernova explosion when the core collapse occurs.[16]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 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.
  2. ↑ 2.0 2.1 2.2 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. Bibcode: 2002yCat.2237....0D. 
  3. ↑ 3.0 3.1 Percy, J. R.; Terziev, E. (2011). "Studies of "Irregularity" in Pulsating Red Giants. III. Many More Stars, an Overview, and Some Conclusions". The Journal of the American Association of Variable Star Observers 39 (1): 1. Bibcode: 2011JAVSO..39....1P. 
  4. ↑ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode: 1989ApJS...71..245K. 
  5. ↑ Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics 430: 165. doi:10.1051/0004-6361:20041272. Bibcode: 2005A&A...430..165F. 
  6. ↑ Levesque, E. M.; Massey, P.; Olsen, K. A. G.; Plez, B.; Josselin, E.; Maeder, A.; Meynet, G. (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not as Cool as We Thought". The Astrophysical Journal 628 (2): 973–985. doi:10.1086/430901. Bibcode: 2005ApJ...628..973L. 
  7. ↑ 7.0 7.1 7.2 Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  8. ↑ Stassun, Keivan G. et al. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256. Bibcode: 2019AJ....158..138S. 
  9. ↑ 9.0 9.1 Dorn-Wallenstein, Trevor Z.; Levesque, Emily M.; Neugent, Kathryn F.; Davenport, James R. A.; Morris, Brett M.; Gootkin, Keyan (2020). "Short Term Variability of Evolved Massive Stars with TESS II: A New Class of Cool, Pulsating Supergiants". The Astrophysical Journal 902 (1): 24. doi:10.3847/1538-4357/abb318. Bibcode: 2020ApJ...902...24D. 
  10. ↑ "Hipparcos Tools Interactive Data Access". ESA. https://www.cosmos.esa.int/web/hipparcos/interactive-data-access. 
  11. ↑ Fleming, Williamina; Pickering, Edward C. (1911). "Stars Having Peculiar Spectra. 31 New Variable Stars". Harvard College Observatory Circular 167: 1. Bibcode: 1911HarCi.167....1F. 
  12. ↑ Kiss, L. L.; Szabó, G. M.; Bedding, T. R. (2006). "Variability in red supergiant stars: Pulsations, long secondary periods and convection noise". Monthly Notices of the Royal Astronomical Society 372 (4): 1721–1734. doi:10.1111/j.1365-2966.2006.10973.x. Bibcode: 2006MNRAS.372.1721K. 
  13. ↑ Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal 38: 309. doi:10.1086/190559. Bibcode: 1978ApJS...38..309H. 
  14. ↑ Josselin, E.; Plez, B. (2007). "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics 469 (2): 671. doi:10.1051/0004-6361:20066353. Bibcode: 2007A&A...469..671J. 
  15. ↑ Mauron, Nicolas; Josselin, Eric (2010). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy & Astrophysics 526: A156. doi:10.1051/0004-6361/201013993. Bibcode: 2011A&A...526A.156M. 
  16. ↑ Meynet, G.; Chomienne, V.; Ekström, S.; Georgy, C.; Granada, A.; Groh, J.; Maeder, A.; Eggenberger, P. et al. (2015). "Impact of mass-loss on the evolution and pre-supernova properties of red supergiants". Astronomy & Astrophysics 575: A60. doi:10.1051/0004-6361/201424671. Bibcode: 2015A&A...575A..60M. 



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