Alpha Delphini

Alpha Delphini (α Delphini, abbreviated Alpha Del, α Del), also named Sualocin,^[1] is a multiple star in the constellation of Delphinus.

Nomenclature

α Delphini (Latinised to Alpha Delphini) is the star's Bayer designation.

It bore an historical name, Sualocin, which arose as follows: Niccolò Cacciatore was the assistant to Giuseppe Piazzi, and later his successor as Director of the Palermo Observatory. The name first appeared in Piazzi's Palermo Star Catalogue. When the Catalogue was published in 1814, the unfamiliar names Sualocin and Rotanev were attached to Alpha and Beta Delphini, respectively. Eventually the Reverend Thomas Webb, a British astronomer, puzzled out the explanation.^[2] Cacciatore's name, Nicholas Hunter in English translation, would be Latinized to Nicolaus Venator. Reversing the letters of this construction produces the two star names. They have endured, the result of Cacciatore's little practical joke of naming the two stars after himself. How Webb arrived at this explanation 45 years after the publication of the catalogue is still a mystery.^[3]

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)^[4] to catalogue and standardize proper names for stars. The WGSN approved the name Sualocin for Alpha Delphini on 12 September 2016 and it is now so entered in the IAU Catalog of Star Names.^[1]

In Chinese, 瓠瓜 (Hù Guā), meaning Good Gourd, refers to an asterism consisting of Alpha Delphini, Gamma² Delphini, Delta Delphini, Beta Delphini and Zeta Delphini.^[5] Consequently, Alpha Delphini itself is known as 瓠瓜一 (Hù Guā yī, English: the First Star of Good Gourd.).^[6]

In Hindu astronomy, the star corresponded to one of the nakshatras named Dhanishta.

Properties

Alpha Delphini has seven components: A and G, a physical binary, and B, C, D, E, and F, which are optical binaries and have no physical association with A and G.

Alpha Delphini A/G Observation data Epoch J2000.0      Equinox J2000.0 (ICRS) Constellation Delphinus Right ascension 20^h 39^m 38.287^s/38.287^s Declination +15° 54′ 43.49″/43.15″ Apparent magnitude (V) 3.9/6.4; combined, 3.77 Distance 241 ± 13 ly (73.8 ± 3.7 pc) Spectral type A: B9V Other designations α Del, 9 Del, BD +15 4222, CCDM J20396+1555A/G, HD 196867, HIP 101958, HR 7906, SAO 106357 Data sources: Hipparcos Catalogue, CCDM (2002)

Alpha Delphini B/C/D/E/F Observation data Epoch J2000.0      Equinox J2000.0 (ICRS) Constellation Delphinus Right ascension 20^h 39^m 36.5^s/34.9^s/39.5^s/35.1^s/42.9^s Declination +15° 54′ 21″/ +15° 54′ 49″/ +15° 54′ 01″/ +15° 55′ 15″/ +15° 54′ 09″ Apparent magnitude (V) 13.4/11.9/12.9/12.6/10.7 Other designations CCDM J20396+1555B/C/D/E/F; also, see designations for Alpha Delphini A/G Data sources: CCDM (2002)

References

1. "IAU Catalog of Star Names". Retrieved 28 July 2016.
2. Webb, T.W. (1859). Celestial Objects for Common Telescopes. London: Longmans, Green and Co. pp. 193–194.
3. Hurn, Mark. "Secrets of the 1814 Palermo Star Catalogue". The Story of Star Names. Mark Hurn, Institute of Astronomy Library, Univ. of Cambridge. Retrieved 11 May 2015.
4. IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
5. (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.
6. (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.

Sources

1. SIMBAD Query Result
2. CCDM catalogue entry at VizieR