Back RW Cephei Afrikaans RW قيفاوس Arabic RW Cephei AST RW Cephei German RW Cephei Spanish آردبلیو قیفاووس Persian RW Cephei French RW בקפאוס HE RW Cephei ID RW Cephei Italian

RW Cephei

RW Cephei
CHARA/MIRC-X image of RW Cephei in the H-band during the "great dimming", revealing a box-like shape and a dark patch on the western side of the star
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cepheus
Right ascension 22h 23m 07.01521s[1]
Declination +55° 57′ 47.6244″[1]
Apparent magnitude (V) +6.65[2] (6.0–7.6[3])
Characteristics
Evolutionary stage Red, orange or yellow hypergiant
Spectral type K2 0-Ia[4] (G8 - M2Ia-0[3])
Apparent magnitude (K) 1.88[2]
U−B color index 2.38[2]
B−V color index 2.22[2]
Variable type SRd[5]
Astrometry
Radial velocity (Rv)−56.00[6] km/s
Proper motion (μ) RA: −3.606[1] mas/yr
Dec.: −2.881[1] mas/yr
Parallax (π)0.1140 ± 0.0342 mas[1]
Distance3,400+220
−200 pc[7][8]
Absolute magnitude (MV)−8.0[9] – −9.4[10]
Details
Radius900–1,760,[11] 940[8][a] R☉
Luminosity300,000[8] L☉
Surface gravity (log g)0.2[12] cgs
Temperature4,200[11]–4,400,[8] 3,900[11] (during the dimming) K
Metallicity [Fe/H]+0.17±0.20[13] dex
Other designations
HD 212466, HIP 110504, SAO 34387, BD+55°2737, AAVSO 2219+55A
Database references
SIMBADdata

RW Cephei is a K-type hypergiant and a semirregular variable star in the constellation Cepheus, at the edge of the Sharpless 132 H II region and close to the small open cluster Berkeley 94. It is among the largest stars known with a radius of almost 1,000 times that of the Sun (R☉), nearly as large as the orbit of Jupiter.

In 2022, the star underwent a "great dimming" event similar to Betelgeuse.

The temperature intermediate between the red supergiants and yellow hypergiants has led to it being variously considered as a red hypergiant[14][15] or yellow hypergiant.[16][17]

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