# 7 Draconis

7 Draconis, also named Tianyi /tiˈɛnjiː/ (or) /ˌtjɛnˈjiː/,[6] is a single[7] star in the northern circumpolar constellation of Draco. It is visible to the naked eye as a faint orange-hued star with a stellar classification of 5.43.[2] Based upon an annual parallax shift of 4.16 mas as seen from the Earth,[1] the star is located approximately 780 light-years from the Sun.

This is an evolved giant star with a stellar classification of K5 III.[2] The measured angular diameter of this star, after correction for limb darkening, is 2.61±0.03 mas.[8] At its estimated distance, this yields a physical size of about 67 times the radius of the Sun.[4] It is radiating about 1,024[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,945 K.[5]

7 Draconis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Draco
Right ascension  12h 47m 34.34473s[1]
Declination +66° 47′ 25.0977″[1]
5.43[2]
Characteristics
Spectral type K5 III[2]
B−V color index 1.567±0.006[2]
Astrometry
Proper motion (μ) RA: 6.674[1] mas/yr
Dec.: −6.498[1] mas/yr
Parallax (π)4.1601 ± 0.1056[1] mas
Distance780 ± 20 ly
(240 ± 6 pc)
Absolute magnitude (MV)−1.35[2]
Details
Luminosity1,024.45[2] L
Temperature3,945[5] K
Other designations
Tianyi, 7 Dra, BD+67°764, FK5 3020, HD 111335, HIP 62423, HR 4863, SAO 15902[3]
Database references

## Nomenclature

7 Draconis is the star's Flamsteed designation.

The star bore the traditional Chinese name of Tianyi,[9] from 天乙 (Tiān Yǐ) or 天一 (Tiān Yī, the Celestial Great One), a deity in Taoism. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalogue and standardize proper names for stars. The WGSN approved the name Tianyi for this star on 30 June 2017 and it is now so entered on the List of IAU-approved Star Names.[6]

## References

1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
3. ^ a b "6 Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-23.
4. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
{\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(240\cdot 2.61\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 134.7\cdot R_{\bigodot }\end{aligned}}}
5. ^ a b McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427: 343, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
6. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
7. ^ Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
8. ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
9. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 7. Retrieved 2018-07-14.
10. ^ "International Astronomical Union | IAU". www.iau.org. Retrieved 2018-01-16.
List of proper names of stars

These names of stars that have either been approved by the International Astronomical Union (its Working Group on Star Names has since 2016 been publishing a "List of IAU-approved Star Names", which as of June 2018 included a total of 330 proper names of stars) or which have been in somewhat recent usage. See also the lists of stars by constellation, which give variant names, derivations, and magnitudes.

Of the roughly 10,000 stars visible to the naked eye, only a few hundred have been given proper names in the history of astronomy. Traditional astronomy tends to group stars into asterisms, and give proper names to those, not to individual stars.

Many star names are in origin descriptive of the part of the asterism they are found in; thus Phecda, a corruption of the Arabic -فخذ الدب- fakhth al-dubb "thigh of the bear". Only a handful of the brightest stars have individual proper names not depending on their asterism; so Sirius "the scorcher", Antares "like Mars", Canopus (of uncertain origin), Alphard "the solitary one", Regulus "kinglet"; and arguably Aldebaran "the follower" (of the Pleiades), Procyon "preceding the dog [Sirius]". The same holds for Chinese star names, where most stars are enumerated within their asterisms, with a handful of exceptions such as 織女 "weaving girl" (Vega).

In addition to the limited number of traditional star names, there are some coined in modern times, e.g. "Avior" for Epsilon Carinae (1930), and a number of stars named after people (mostly in the 20th century).

Tianyi

Tianyi may refer to:

Tianyi Pavilion, Ningbo, the oldest existing library in China

Tianyi Square, Ningbo

Tianyi Film Company, one of the biggest film production companies in pre-World War II China

Tianyi UAV

Tianyi, the proper name of the star 7 Draconis

Luo Tianyi, Chinese vocaloid character

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