PZ Cassiopeiae

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PZ Cassiopeiae
LBN 114.55+00.22.jpg
PZ Cassiopeiae is the bright star towards the 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)8.2 – 10.2 [2]
Characteristics
Evolutionary stage Red supergiant
Spectral type M3Iab [3]
U−B color index +1.32 [4]
B−V color index +2.58 [4]
Variable type SRc [5] + Cepheid [6]
Astrometry
Radial velocity (Rv)–45.68 [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
Mass 20 or 25 (initial mass) [8]   M☉
Radius 1,259—1,336, [8] [lower-alpha 1] 1,231 [10]   R☉
Luminosity 229,000, [11]
(240,000 –270,000 [8] )  L☉
Surface gravity (log g)−0.5 [9]   cgs
Temperature 3,605 [3]   K
Age 8 or 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 1,200 times the Sun's radius (R☉), and also one of the most luminous of its type, around 240,000 times more luminous than the Sun (L☉). [10] 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. [12] [13]

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] [11]

A 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☉. [14]

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, [16] although periods of 850 and 3,195 days have been derived. [5] [2] The visual range is approximate magnitude 8–10, large for this type of variable. [2]

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. [17]

Companion

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

Notes

  1. ↑ Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772  K:
    .
    .

Related Research Articles

<span class="mw-page-title-main">Supergiant</span> Type of star that is massive and luminous

Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spans from about 3,400 K to over 20,000 K.

<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 and a stellar classification 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">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 4,700 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.

<span class="mw-page-title-main">Arches Cluster</span>

The Arches Cluster is the densest known star cluster in the Milky Way, about 100 light-years from its center in the constellation Sagittarius, 25,000 light-years from Earth. Its discovery was reported by Nagata et al. in 1995, and independently by Cotera et al. in 1996. Due to extremely heavy optical extinction by dust in this region, the cluster is obscured in the visual bands, and is observed in the X-ray, infrared and radio bands. It contains approximately 135 young, very hot stars that are many times larger and more massive than the Sun, plus many thousands of less massive stars.

<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">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">WOH G64</span> Red supergiant in the constellation Dorado

WOH G64 is an unusual red supergiant (RSG) star in the Large Magellanic Cloud (LMC) satellite galaxy in the southern constellation of Dorado. It is one of the largest known stars, being described as possibly being the largest star known. It is also one of the most luminous and massive red supergiants, with a radius calculated to be around 1,540 times that of the Sun (R☉) and a luminosity around 282,000 times the solar luminosity (L☉).

<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. A common example of a hypergiant is UY Scuti, although being a supergiant UY Scuti is considered a hypergiant by some people.

<span class="mw-page-title-main">VX Sagittarii</span> Asymptotic giant branch star in the constellation Sagittarius

VX Sagittarii is an asymptotic giant branch star located more than 1.5 kiloparsec away from the Sun in the constellation of Sagittarius. It is a pulsating variable star with an unusually large magnitude range. It is one of the largest stars discovered, with a radius varying between 1,350 and 1,940 solar radii (940,000,000 and 1.35×109 km; 6.3 and 9.0 au). It is the most luminous known AGB star, at bolometric magnitude –8.6, which is brighter than the theoretical limit at –8.0.

<span class="mw-page-title-main">R Scuti</span> Variable star in the constellation Scutum

R Scuti is a star in the constellation of Scutum. It is a yellow supergiant and is a pulsating variable known as an RV Tauri variable. It was discovered in 1795 by Edward Pigott at a time when only a few variable stars were known to exist.

<span class="mw-page-title-main">HD 33579</span> Star in the constellation Dorado

HD 33579 is a white/yellow hypergiant and one of the brightest stars in the Large Magellanic Cloud (LMC). It is a suspected variable star.

<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">HD 179821</span> Star in the constellation Aquila

HD 179821 or V1427 Aquilae is either a post-red supergiant yellow hypergiant or a post-AGB yellow supergiant star in the constellation of Aquila, surrounded by a detached dust shell. It is a semi-regular variable nearing the end of its life.

<span class="mw-page-title-main">V915 Scorpii</span> Variable star in the constellation Scorpius

V915 Scorpii is a hypergiant and semiregular variable star, located 1,718 parsecs (5,600 ly) away in the constellation Scorpius. Its apparent magnitude varies between 6.22 and 6.64, being heavily diminshed by 2.93 magnitudes due to interstellar extinction.

<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">HD 143183</span> Star in the constellation Norma

HD 143183 is a red supergiant variable star of spectral type M3Ia in constellation Norma. It is a member of the Norma OB1 association, at a distance of about 2 kiloparsecs. It is one of the most luminous red supergiants with a luminosity over 100,000 times greater than the Sun (L☉), and is as well one of the largest stars with a radius more than a thousand times that of the Sun (R☉). Older studies frequently calculated higher luminosities and radii. It has an estimated mass loss rate of 5×10−5 M☉ per year and has been once described as a cool hypergiant. It is surrounded by a dozen early-type stars and a circumstellar nebula which extends 0.12 parsecs (0.39 ly).

References

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  3. 1 2 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 . Bibcode:2009A&A...498..127V. doi: 10.1051/0004-6361/20079063 . ISSN   0004-6361.
  4. 1 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.
  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 6 7 8 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. 1 2 Healy, Sarah; Horiuchi, Shunsaku; Molla, Marta Colomer; Milisavljevic, Dan; Tseng, Jeff; Bergin, Faith; Weil, Kathryn; Tanaka, Masaomi (23 March 2024). "Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova". Monthly Notices of the Royal Astronomical Society. 529 (4): 3630–3650. arXiv: 2307.08785 . doi: 10.1093/mnras/stae738 . ISSN   0035-8711.
  11. 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.
  12. ↑ 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.
  13. ↑ Stickland, D. J. (1985). "IRAS observations of the cool galactic hypergiants". The Observatory. 105: 229. Bibcode:1985Obs...105..229S.
  14. ↑ 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.
  15. ↑ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  16. ↑ 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.
  17. ↑ 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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