RW Cephei

Observational Data
Designation |  Rw Cep
HD 21246
HIP 110504
Right ascension |  22h 23m 07.0152s[1][2]
Declination |  +55° 57′ 47.6161″[1][2]
Constellation |  Cepheus
Type of object |  Supergiant star
Magnitude |  Apparent Mag: +6.44[3]
Absolute Mag: -3.18 / -4.02[3]
Astrometry
Distance from Earth |  4026.71 ly[3]
Radial velocity |  -56.00 ± 5.7 km/s[1][4]
Proper motion |  RA: -3.616 mas/yr[1][2]
Dec: -2.349mas/yr[1][2]
Parallax |  0.2357 ± 0.0944 mas[1][2]

RW Cephei (Rw Cep, HD 21246, HIP 110504) is a supergiant star in the constellation of Cepheus.[3] It is not part of the constellation itself, but does lie within the borders of Cepheus. The star is one of the largest stars known with a radius nearly 1,600 greater than the Sun's.[5] The star is sufficiently bright that it does not require binoculars or a telescope to observe it.

RW Cephei is situated roughly 4026.71 light years from Earth.[3] The star is truly huge, thought to have a radius of 1,535 solar radii and a mass of 13.7 solar masses.[5] The temperature of the star is thought to be low at 590 kelvin.[3] The prefix "RV" in the name identifies RW Cephei as a variable star, meaning its brightness changes over time. It is classified as a pulsating, slow regular variable. The Star slowly expands and contracts over time in a regular and predictable manner. As it does so, the brightness varies between +6.456 and +6.620 over a period of 0.170 days or four hours.[3][6]

The star is not known to have any exoplanets.

## References[edit]

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 RW Cephei. Simbad Astronomical Database. simbad.u-strasbg.fr. Retrieved on June 22, 2020.
2. ↑ 2.0 2.1 2.2 2.3 2.4 Gaia Collaboration (2018). "VizieR Online Data Catalog: Gaia DR2". VizieR Online Data Catalog I/345: I/345. Bibcode: 2018yCat.1345....0G. arXiv:0708.1752
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 RW Cephei (Supergiant Star) Star Facts. universeguide.com. Retrieved on June 22, 2020.
4. ↑ Kharchenko, N. V.; Scholz, R. -D.; Piskunov, A. E. et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of 55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten 328 (9): 889. doi:10.1002/asna.200710776. Bibcode: 2007AN....328..889K. arXiv:0705.0878
5. ↑ 5.0 5.1 Nola Taylor Redd (July 26, 2018). What Is the Biggest Star?. space.com. Retrieved on June 22, 2020.
6. ↑ Irregular and Semi-Regular Variable Stars. universeguide.com. Retrieved on June 22, 2020.

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