TZ Cassiopeiae

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TZ Cassiopeiae
Cassiopeia constellation map.svg
Location of TZ Cas
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 23h 52m 56.23733s[1]
Declination 61° 00′ 08.3786″[1]
Apparent magnitude (V) 9.18[2] (+8.86 - +10.5[3])
Spectral type M3 Iab[4]
U−B color index +2.43[2]
B−V color index +2.57[2]
Variable type Lc[3]
Radial velocity (Rv) −54.28[5] km/s
Proper motion (μ) RA: −2.77[1] mas/yr
Dec.: −3.10[1] mas/yr
Parallax (π) 0.39 ± 0.76[1] mas
Distance 2,400[6] pc
Absolute magnitude (MV) −5.98[7]
Mass 15[8] M
Radius 645[8] R
Luminosity 69,000[8] L
Surface gravity (log g) −0.01[8] cgs
Temperature 3,670[8] K
Other designations
BD+60°2634, HIP 117763, SAO 20192, 2MASS J23525623+6100083, AAVSO 2348+60
Database references

TZ Cassiopeaie (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 8,000 light-years away from Earth. The star is a red supergiant star with a spectral type of M3 and a temperature of 3,670 Kelvin. It is currently around 15 M

TZ Cassiopeiae was reported as being variable by Williamina Fleming and published posthumously in 1911.[9] It is a slow irregular variable star with a possible period of 3,100 days.[10] It is approximately 69,000 times the luminosity of the Sun, and it is 645 times bigger than the Sun. It is a member of the Cas OB5 stellar association, together with the nearby red supergiant PZ Cassiopeiae.[11]

TZ Cas is losing mass through a powerful stellar wind at two millionths of a solar mass each year.[6] 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.[12]

See also[edit]


  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c 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. ^ a b 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. 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. Bibcode:1989ApJS...71..245K. doi:10.1086/191373. 
  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. Bibcode:2005A&A...430..165F. arXiv:astro-ph/0409579Freely accessible. doi:10.1051/0004-6361:20041272. 
  6. ^ a b Mauron, Nicolas; Josselin, Eric (2010). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy & Astrophysics. 526: A156. Bibcode:2011A&A...526A.156M. arXiv:1010.5369v1Freely accessible. doi:10.1051/0004-6361/201013993. 
  7. ^ 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. Bibcode:2005ApJ...628..973L. arXiv:astro-ph/0504337Freely accessible. doi:10.1086/430901. 
  8. ^ a b c d e Josselin, E.; Plez, B. (2007). "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics. 469 (2): 671. Bibcode:2007A&A...469..671J. arXiv:0705.0266Freely accessible. doi:10.1051/0004-6361:20066353. 
  9. ^ Fleming, Williamina; Pickering, Edward C. (1911). "Stars Having Peculiar Spectra. 31 New Variable Stars". Harvard College Observatory Circular. 167: 1. Bibcode:1911HarCi.167....1F. 
  10. ^ 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. Bibcode:2006MNRAS.372.1721K. arXiv:astro-ph/0608438Freely accessible. doi:10.1111/j.1365-2966.2006.10973.x. 
  11. ^ Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal. 38: 309. Bibcode:1978ApJS...38..309H. doi:10.1086/190559. 
  12. ^ Meynet, G.; Chomienne, V.; Ekström, S.; Georgy, C.; Granada, A.; Groh, J.; Maeder, A.; Eggenberger, P.; Levesque, E.; Massey, P. (2015). "Impact of mass-loss on the evolution and pre-supernova properties of red supergiants". Astronomy & Astrophysics. 575: A60. Bibcode:2015A&A...575A..60M. arXiv:1410.8721Freely accessible. doi:10.1051/0004-6361/201424671.