Alpha Equulei

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Alpha Equulei
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Equuleus
Right ascension 21h 15m 49.40s
Declination +5° 14′ 53.1″
Apparent magnitude (V) +3.92
Absolute magnitude (V) +0.20;[1] +0.14
Distance 186 ly
(57.05 pc)
Spectral type G0 III+
Other designations
Kitalphar, 8 Equulei, HR 8131, HD 202447, BD +04 4635, HIP 104987, SAO 126662, FK5 800, GC 29735

Alpha Equulei (α Equ, α Equulei) is a star in the constellation Equuleus. It has the traditional name Kitalpha (rarely Kitel Phard or Kitalphar), a contraction of the Arabic name قطعة الفرس qiṭ‘a(t) al-faras "a piece of the horse".

In Chinese, 虚宿 (Xū Sù), meaning Emptiness, is an asterism consisting of α Equulei and β Aquarii.[2] Consequently, α Equulei itself is known as 虛宿二 (Xū Sù èr, English: the Second Star of Emptiness.)[3]

Alpha Equulei collectively belongs to spectral class G0III and has apparent magnitude +3.92 and a luminosity approximately 75 times that of the Sun. Alpha Equulei is a unique spectroscopic binary star consisting of two components. Kitalpha is approximately 186 light years from Earth.

This star has 2.72 times the mass of the Sun, with a projected rotational velocity of 20.0 km s−1 and an estimated rotation period of 98.8 days.[1]


  1. ^ a b Pizzolato, N.; Maggio, A.; Sciortino, S. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics, 361: 614–628, Bibcode:2000A&A...361..614P 
  2. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  3. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.

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