Alpha Lacertae

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title: "Alpha Lacertae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["a-type-main-sequence-stars", "double-stars", "lacerta", "bayer-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects", "stars-with-proper-names", "lucidae"] description: "Star in the constellation Lacerta" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Alpha_Lacertae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star in the constellation Lacerta ::

| name = α Lacertae | image = |image=Lacerta constellation map.svg|alt=|float=center|width=240 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=α Lacertae |x=485|y=550 | caption = Location of α Lacertae (circled in red) | epoch = J2000.0 | equinox = J2000.0 (ICRS) | constell = Lacerta | ra = | dec = | appmag_v = 3.76 | type = main sequence | class = A1 V | u-b = 0.00 | b-v = | r-i = −0.03 | radial_v = | prop_mo_ra = 137.51 | prop_mo_dec = 17.01 | parallax = 31.79 | p_error = 0.12 | parallax_footnote = | absmag_v = 1.27 | source = | mass = 2.194 | radius = | luminosity = | temperature = | gravity = | rotational_velocity = 128 | age_myr = 400 | names= | Simbad=alf+lac

Alpha Lacertae, also named Stellio, is a single white-hued star in the constellation of Lacerta, located 103 light-years from the Sun. It is the brightest star in Lacerta with an apparent visual magnitude of 3.76. The star is moving closer to the Earth with a heliocentric radial velocity of −4.5 km/s.

This is an ordinary A-type main-sequence star with a stellar classification of A1 V, which indicates it is generating energy through hydrogen fusion at its core. It is around 400 million years old with a relatively high rate of spin, showing a projected rotational velocity of 128 km/s. The star has 2.2 times the mass of the Sun and 2.1 times the Sun's radius. It is radiating 28 times the Sun's luminosity from its photosphere at an effective temperature of .

Alpha Lacertae has a visual companion, CCDM J22313+5017B, of spectral type A and apparent visual magnitude 11.8, approximately 36 arcseconds away. The companion is optical, a chance line-of-sight coincidence.

Naming

::figure[src="https://upload.wikimedia.org/wikipedia/commons/3/3e/Alpha_Lacertae.jpg" caption="α Lacertae in optical light"] ::

Alpha Lacertae, Latinised from α Lacertae, is the Bayer designation for this star; it has the Flamsteed designation 7 Lacertae.

In Chinese astronomy, 螣蛇 (Téng Shé), meaning Flying Serpent, refers to an asterism consisting of α Lacertae, 4 Lacertae, π2 Cygni, π1 Cygni, HD 206267, ε Cephei, β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, λ Andromedae, κ Andromedae, ι Andromedae, and ψ Andromedae. Consequently, the Chinese name for α Lacertae itself is 螣蛇一 (Téng Shé yī, ).

The IAU Working Group on Star Names approved the name Stellio for this star on 29 August 2024 and it is now so entered in the IAU Catalog of Star Names. Stellio is an obsolete historical name for the constellation Lacerta, named after the lizard Laudakia stellio, the starred agama or stellion.

References

References

1. {{in lang. zh [http://aeea.nmns.edu.tw/2006/0607/ap060707.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日] {{Webarchive. link. (2011-05-21)
2. "HD 211073".
3. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics.
4. CDS]] ID [https://vizier.u-strasbg.fr/viz-bin/Cat?V/50 V/50]. Accessed on line September 3, 2008.
5. "IAU Catalog of Star Names".
6. Ridpath, Ian. "Star Tales - Lacerta".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::