PZ Cassiopeiae

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PZ Cassiopeiae
LBN 114.55+00.22.jpg
PZ Cassiopeiae is the bright star towards upper right in this WISE infrared image.
Observation data
Epoch J2000       Equinox J2000
Constellation Cassiopeia
Right ascension 23h 44m 03.28104s [1]
Declination +61° 47′ 22.1823″ [1]
Apparent magnitude  (V)8.90 [2] (8.2 – 10.2 [3] )
Characteristics
Evolutionary stage Red supergiant
Spectral type M3Ia [4]
U−B color index +1.32 [2]
B−V color index +2.58 [2]
Variable type SRc [5] + Cepheid [6]
Astrometry
Radial velocity (Rv)–45.68 ± 0.68 [7]  km/s
Proper motion (μ)RA: −4.15 [1]   mas/yr
Dec.: −3.55 [1]   mas/yr
Parallax (π)0.356 ± 0.026  mas [8]
Distance 2,810+220
−190 [8]   pc
Absolute magnitude  (MV)−7.89 [9]
Details
Radius (1190 ± 238) – (1940 ± 388); [10] 1364 [11]   R☉
Luminosity 229,000 [12]   L☉
Surface gravity (log g)−0.5 [9]   cgs
Temperature 3,605±170 [13]   K
Age 8 – 10 [8]   Myr
Other designations
PZ  Cas, IRC +60417, HIP 117078, BD+60°2613, RAFGL  3138
Database references
SIMBAD data

PZ Cassiopeiae is a red supergiant star located in the constellation of Cassiopeia, and a semi-regular variable star.

Contents

Characteristics

PZ Cassiopeiae is a luminous red supergiant star, one of the largest stars currently known with a radius over 1,000 times the Sun's radius (R☉), and also one of the most luminous of its type, around 200,000 times more luminous than the Sun (L☉). It is likely to be part of the Cas OB5 stellar association although apparently much younger than the other stars in the association. [8] The star is losing mass at around 2.6×10−5  M☉ per year and has also once been described as a hypergiant. [14] [15]

Its distance from Earth was initially estimated to be around 7,800 light-years (2.4 kiloparsecs). Subsequent studies of the star using the water masers that surround it have allowed to refine both the distance and the parameters of this star, deriving an accurate parallax of 0.356±0.026  mas , corresponding to a distance of 9,160 light-years (2.81 kiloparsecs), that translates a luminosity for it around 229,000 L☉, and an initial mass of 20 to 25 times that of the Sun. These parameters are all similar to those estimated for the red hypergiant VY Canis Majoris. [8] [12]

A less reliable Gaia Data Release 2 parallax of 0.42±0.09  mas gives the star a luminosity below 180,000 L☉ with a corresponding radius of 1,062 R☉. [13]

A visual band light curve of PZ Cassiopeiae, from AAVSO data PZCasLightCurve.png
A visual band light curve of PZ Cassiopeiae, from AAVSO data

PZ Cas is a slow semi-regular variable star with the period quoted as 925 days in the General Catalogue of Variable Stars, [17] although periods of 850 and 3,195 days have been derived. [5] [3] The visual range is approximate magnitude 8–10, large for this type of variable. [3]

Supergiant or AGB star

PZ Cas has traditionally been treated as a massive supergiant, comparable to others such as VY CMa, but there is some evidence that it is a possible less massive O-rich S- or SC-type Asymptotic Giant Branch (AGB) or post-AGB star. It shows enrichment of Zr and Ba, but not Li as would be expected for a true supergiant. [18]

Companion

PZ Cas has a Cepheid variable companion, a 13th magnitude star 12" away. [6]

See also

Related Research Articles

<span class="mw-page-title-main">Red supergiant</span> Stars with a supergiant luminosity class with a spectral type of K or M

Red supergiants (RSGs) are stars with a supergiant luminosity class of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares A are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars.

<span class="mw-page-title-main">Rho Cassiopeiae</span> Yellow hypergiant star in the constellation Cassiopeia

Rho Cassiopeiae is a yellow hypergiant star in the constellation Cassiopeia. It is about 3,400 light-years (1,000 pc) from Earth, yet can still be seen by the naked eye as it is over 300,000 times brighter than the Sun. On average it has an absolute magnitude of −9.5, making it visually one of the most luminous stars known. Its diameter measures between 636 and 981 times that of the Sun, approximately 1,125,000,000 kilometers, or almost four times the size of Earth's orbit.

<span class="mw-page-title-main">Mu Cephei</span> Red supergiant star in the constellation Cepheus

Mu Cephei, also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as a spectral standard by which other stars are classified.

<span class="mw-page-title-main">KY Cygni</span> Star in the constellation Cygnus

KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 5,000 light-years away.

<span class="mw-page-title-main">Phi Cassiopeiae</span> Star in the constellation Cassiopeia

Phi Cassiopeiae is a multiple star in the constellation Cassiopeia with a combined apparent magnitude of +4.95. The two brightest components are A and C, sometimes called φ1 and φ2 Cas. φ Cas A is an F0 bright supergiant of magnitude 4.95 and φ Cas C is a 7.08 magnitude B6 supergiant at 134".

<span class="mw-page-title-main">Yellow hypergiant</span> Class of massive star with a spectral type of A to K

A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually luminous stars, with absolute magnitude (MV) around −9, but also one of the rarest, with just 20 known in the Milky Way and six of those in just a single cluster. They are sometimes referred to as cool hypergiants in comparison with O- and B-type stars, and sometimes as warm hypergiants in comparison with red supergiants.

KW Sagittarii is a red supergiant, located approximately 1,900 parsecs away from the Sun in the direction of the constellation Sagittarius. It is one of the largest-known stars. If placed at the center of the Solar System, the star's surface would engulf Mars.

<span class="mw-page-title-main">V354 Cephei</span> Star in the constellation Cepheus

V354 Cephei is a red supergiant star located within the Milky Way. It is an irregular variable located over 8,900 light-years away from the Sun. It has an estimated radius of 685 solar radii. If it were placed in the center of the Solar System, it would extend to between the orbits of Mars and Jupiter.

<span class="mw-page-title-main">Zeta Cephei</span> Star in the constellation Cepheus

Zeta Cephei is a star in the constellation of Cepheus. Zeta Cephei marks the left shoulder of Cepheus, the King of Joppa (Ethiopia). It is one of the fundamental stars of the MK spectral sequence, defined as type K1.5 Ib.

<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

S Persei is a red supergiant or hypergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.

<span class="mw-page-title-main">NO Aurigae</span> Star in the constellation Auriga

NO Aurigae is a pulsating variable star in the constellation Auriga. It is an unusually-luminous asymptotic giant branch star about 3,500 light years away.

<span class="mw-page-title-main">6 Cassiopeiae</span> Star in the constellation Cassiopeia

6 Cassiopeiae is a white hypergiant in the constellation Cassiopeia, and a small-amplitude variable star.

<span class="mw-page-title-main">Hypergiant</span> Rare star with tremendous luminosity and high rates of mass loss by stellar winds

A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term hypergiant is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications, except for specific well-defined groups such as the yellow hypergiants, RSG (red supergiants), or blue B(e) supergiants with emission spectra. More commonly, hypergiants are classed as Ia-0 or Ia+, but red supergiants are rarely assigned these spectral classifications. Astronomers are interested in these stars because they relate to understanding stellar evolution, especially star formation, stability, and their expected demise as supernovae.

<span class="mw-page-title-main">V602 Carinae</span> Star in the constellation Carina

V602 Carinae is a red supergiant and variable star of spectral type of M3 in the constellation Carina. It is one of largest known stars.

<span class="mw-page-title-main">TZ Cassiopeiae</span> Star in the constellation Cassiopeia

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.

<span class="mw-page-title-main">BC Cygni</span> Star in the constellation Cygnus

BC Cygni is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.

<span class="mw-page-title-main">RW Cygni</span> Star in the constellation Cygnus

RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni. Its apparent magnitude varies between 8.05 and 9.70 and its spectral type between M3 and M4.

<span class="mw-page-title-main">BI Cygni</span> Star in the constellation Cygnus

BI Cygni(BI Cyg, IRC +40408, BD+36 4025) is a red supergiant in the constellation Cygnus. It is an irregular variable star with a maximum brightness of magnitude 8.4 and a minimum of magnitude 9.9. It is considered a member of the stellar Cygnus OB1 association, its distance is around 2,600 parsecs (8,500 ly) of the Solar System. It is less than a degree south of another variable red supergiant, BC Cygni.

<span class="mw-page-title-main">V528 Carinae</span> Star in the constellation Carina

V528 Carinae is a variable star in the constellation Carina.

<span class="mw-page-title-main">BO Carinae</span> Star in the constellation Carina

BO Carinae, also known as HD 93420, is an irregular variable star in the constellation Carina.

References

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  2. 1 2 3 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.
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  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. 1 2 Le Squeren, A. M.; Sivagnanam, P.; Dennefeld, M.; David, P. (1992). "A Complete Survey of OH / Infrared Objects from the IRAS LRS Sources Within a Domain of the Color Diagram". Astronomy and Astrophysics. 254: 133. Bibcode:1992A&A...254..133L.
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  7. ↑ 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. arXiv: astro-ph/0409579 . Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID   17804304.
  8. 1 2 3 4 5 Kusuno, K.; Asaki, Y.; Imai, H.; Oyama, T. (2013). "Distance and Proper Motion Measurement of the Red Supergiant, Pz Cas, in Very Long Baseline Interferometry H2O Maser Astrometry". The Astrophysical Journal. 774 (2): 107. arXiv: 1308.3580 . Bibcode:2013ApJ...774..107K. doi:10.1088/0004-637X/774/2/107. S2CID   118867155.
  9. 1 2 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. arXiv: astro-ph/0504337 . Bibcode:2005ApJ...628..973L. doi:10.1086/430901. S2CID   15109583.
  10. ↑ Levesque, Emily M.; Massey, Philip; Olsen, K. A. G.; Plez, Bertrand; Josselin, Eric; Maeder, Andre; Meynet, Georges (August 2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, But Not As Cool As We Thought". The Astrophysical Journal. 628 (2): 973–985. arXiv: astro-ph/0504337 . doi:10.1086/430901. ISSN   0004-637X.
  11. ↑ Verhoelst, T.; Zypen, N. Van der; Hony, S.; Decin, L.; Cami, J.; Eriksson, K. (1 April 2009). "The dust condensation sequence in red supergiant stars". Astronomy & Astrophysics. 498 (1): 127–138. arXiv: 0901.1262 . doi:10.1051/0004-6361/20079063. ISSN   0004-6361.
  12. 1 2 Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS . 493 (1): 468–476. arXiv: 2001.06020 . Bibcode:2020MNRAS.493..468D. doi:10.1093/mnras/staa174. S2CID   210714093.
  13. 1 2 Messineo, M.; Brown, A. G. A. (2019). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal. 158 (1): 20. arXiv: 1905.03744 . Bibcode:2019AJ....158...20M. doi: 10.3847/1538-3881/ab1cbd . S2CID   148571616.
  14. ↑ Mauron, N.; Josselin, E. (2011). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy and Astrophysics. 526: A156. arXiv: 1010.5369 . Bibcode:2011A&A...526A.156M. doi:10.1051/0004-6361/201013993. S2CID   119276502.
  15. ↑ Stickland, D. J. (1985). "IRAS observations of the cool galactic hypergiants". The Observatory. 105: 229. Bibcode:1985Obs...105..229S.
  16. ↑ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  17. ↑ 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. Bibcode:2009yCat....102025S.
  18. ↑ García-Hernández, D. A.; García-Lario, P.; Plez, B.; Manchado, A.; d'Antona, F.; Lub, J.; Habing, H. (2007). "Lithium and zirconium abundances in massive Galactic O-rich AGB stars". Astronomy and Astrophysics. 462 (2): 711. arXiv: astro-ph/0609106 . Bibcode:2007A&A...462..711G. doi:10.1051/0004-6361:20065785. S2CID   16016698.
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