Chi Sagittarii

The Bayer designation Chi Sagittarii (χ Sagittarii) is shared by three star systems in the zodiac constellation of Sagittarius. The brightest of these, χ¹ Sagittarii and χ³ Sagittarii, are separated by 0.56° on the sky. The dimmer star χ² Sagittarii is located between them, 0.10° from χ¹, and is too faint to be seen with the naked eye. In 1977, the Wow! signal came from the direction of these stars.

• χ¹ Sagittarii, 47 Sgr, HR 7362
• χ² Sagittarii, 48 Sgr
• χ³ Sagittarii, 49 Sgr, HR 7363

Name and etymology

These three χ star, together with φ Sgr, σ Sgr, ζ Sgr and τ Sgr were Al Naʽām al Ṣādirah (النعم السادرة), the Returning Ostriches.^[1] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Naʽām al Ṣādirah or Namalsadirah was originally the title for four stars: φ Sgr as Namalsadirah I, τ Sgr as Namalsadirah II, χ¹ Sgr as Namalsadirah III and χ² Sgr as Namalsadirah IV (except σ Sgr and ζ Sgr).^[2] In Chinese, 狗 (Gǒu), meaning Dog, refers to an asterism consisting of χ¹ Sagittarii and 52 Sagittarii. Consequently, χ¹ Sagittarii itself is known as 狗二 (Gǒu èr, English: the Second Star of Dog.)^[3]

References

1. Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 355. ISBN 0-486-21079-0. Retrieved 2012-09-04.
2. Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), California Institute of Technology: Jet Propulsion Laboratory, retrieved 2017-07-05.
3. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 2 日