Epoch J2000.0 Equinox J2000.0
|Right ascension||18h 20m 59.64354s|
|Declination||−29° 49′ 41.1659″|
|Apparent magnitude (V)||+2.70|
|Spectral type||K3 III|
|U−B color index||+1.55|
|B−V color index||+1.38|
|Radial velocity (Rv)||–19.9 km/s|
|Proper motion (μ)||RA: +32.54 mas/yr
Dec.: −25.57 mas/yr
|Parallax (π)||9.38 ± 0.18 mas|
|Distance||348 ± 7 ly
(107 ± 2 pc)
|Absolute magnitude (MV)||−1.99|
Delta Sagittarii (δ Sagittarii, abbreviated Delta Sgr, δ Sgr), also named Kaus Media, is a double star in the southern zodiac constellation of Sagittarius. The apparent visual magnitude of this star is +2.70, making it easily visible to the naked eye. Parallax measurements place the distance at roughly 348 light-years (107 parsecs) from the Sun.
It has three dim companions:
- a 14th magnitude star at a separation of 26 arcseconds,
- a 15th magnitude star at a separation of 40 arcseconds, and
- a 13th magnitude star at a separation of 58 arcseconds from the primary.
It is not certain that these stars form a physical system or whether they are merely aligned by chance.
It bore the traditional names Kaus Media, Kaus Meridionalis, and Media, which derive from the Arabic قوس qaws 'bow' and Latin media 'middle'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Kaus Media for this star.
In Chinese, 箕 (Jī), meaning Winnowing Basket, refers to an asterism consisting of Delta Sagittarii, Gamma Sagittarii, Epsilon Sagittarii and Eta Sagittarii. Consequently, Delta Sagittarii itself is known as 箕宿二 (Jī Sù èr, English: the Second Star of Winnowing Basket.)
This star, together with :
- Gamma Sagittarii, Epsilon Sagittarii, Zeta Sagittarii, Lambda Sagittarii, Sigma Sagittarii, Tau Sagittarii and Phi Sagittarii, comprise the asterism 'Teapot'.
- Gamma Sagittarii, Epsilon Sagittarii and Eta Sagittarii were Al Naʽām al Wārid (النعم الوارد), the 'Going Ostriches'.
- Gamma Sagittarii and Epsilon Sagittarii were Akkadian Sin-nun‑tu, or Si-nu-nu‑tum, 'the Swallow'.
In the Hindu system of astrology, this star is also called Purvashada Nakshatra.
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