Regulus - wikipedia Regulus This article is about the star. For other uses, see Regulus ( disambiguation ). Regulus Location of Regulus in Leo Observation data Epoch J2000 Equinox J2000 Constellation Leo Right ascension A : 10 08 22.311 BC : 10 08 12.8 / 14 Declination A : + 11 ° 58 ′ 01.95 '' BC : + 11 ° 59 ′ 48 '' Apparent magnitude ( V ) 1.40 / 8.13 / 13.50 Characteristics Evolutionary stage Main sequence Spectral type B8 IVn + K2 V + M4 V U − B color index -- 0.36 / + 0.51 B − V color index -- 0.11 / + 0.86 Variable type Suspected Astrometry Radial velocity ( R ) + 5.9 / + 6.3 km / s Proper motion ( μ ) RA : - 248.73 ± 0.35 mas / yr Dec. : 5.59 ± 0.21 mas / yr Parallax ( π ) 41.13 ± 0.35 mas Distance 79.3 ± 0.7 ly ( 24.3 ± 0.2 pc ) Absolute magnitude ( M ) -- 0.57 / 6.3 / 11.6 Details α Leo A Mass 3.8 M Radius 3.092 ± 0.147 R Luminosity 288 L Surface gravity ( log g ) 3.54 ± 0.09 cgs Temperature 12,460 ± 200 K Rotational velocity ( v sin i ) 347 km / s Age ≳ 1 Gyr α Leo B / C Mass 0.8 / 0.3 M Radius 0.5 / ? R Luminosity 0.50 / ? L Surface gravity ( log g ) 4.4 / ? cgs Temperature 4885 / ? K Other designations Alpha Leonis, 32 Leo, Cor Leonis, Aminous Basilicus, Lion 's Heart, Rex, Kalb al Asad, Kabeleced, FK5 380, GCTP 2384.00, GJ 9316, HIP 49669, HR 3982. α Leo A : BD + 12 2149, HD 87901, LTT 12716, SAO 98967. α Leo B / C : BD + 12 2147, HD 87884, LTT 12714, SAO 98966. Database references SIMBAD data Regulus, also designated Alpha Leonis ( α Leonis, abbreviated Alpha Leo, α Leo ), is the brightest star in the constellation of Leo and one of the brightest stars in the night sky, lying approximately 79 light years from the Sun. Regulus is a multiple star system composed of four stars that are organized into two pairs. The spectroscopic binary Regulus A consists of a blue - white main - sequence star and its companion, which has not yet been directly observed, but is probably a white dwarf. Located farther away are Regulus B, C, and D, which are dim main - sequence stars. Contents 1 Nomenclature 2 Observations 3 System 4 Visibility 5 Etymology and cultural associations 6 See also 7 References 8 External links Nomenclature α Leonis ( Latinized to Alpha Leonis ) is the star 's Bayer designation. The traditional name Rēgulus is Latin for ' prince ' or ' little king '. 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 Regulus for this star. It is now so entered in the IAU Catalog of Star Names. Observations Regulus is 0.46 degree from the ecliptic, the closest of the bright stars, and is regularly occulted by the Moon. Occultations by the planets Mercury and Venus are possible but rare, as are occultations by asteroids. The last occultation of Regulus by a planet was on July 7, 1959, by Venus. The next will occur on October 1, 2044, also by Venus. Other planets will not occult Regulus over the next few millennia because of their node positions. An occultation of Regulus by the asteroid 166 Rhodope was observed by 12 researchers from Portugal, Spain, Italy, and Greece on October 19, 2005. Differential bending of light was measured to be consistent with general relativity. Regulus was occulted by the asteroid 163 Erigone in the early morning of March 20, 2014. The center of the shadow path passed through New York and eastern Ontario, but no one is known to have seen it, due to cloud cover. The International Occultation Timing Association recorded no observations at all. Although best seen in the evening in northern hemisphere in late winter and spring, Regulus appears at some time of night throughout the year except for about a month on either side of August 22, when the Sun is too near. Regulus passes through SOHO 's LASCO C3 every August. For most Earth observers, the heliacal rising of Regulus occurs in the first week of September. Every 8 years, Venus passes Regulus around the time of the star 's heliacal rising, as on 5 September 2014. System Regulus is a multiple star system consisting of at least four stars. Regulus A is the dominant star, with a binary companion 177 '' distant that is thought to be physically related. Regulus D is a 12th magnitude companion at 212 ``, which shares a common motion with the other stars. Regulus A is a binary star consisting of a blue - white main sequence star of spectral type B7V, which is orbited by a star of at least 0.3 solar masses, which is probably a white dwarf. The two stars take approximately 40 days to complete an orbit around their common centre of mass. Given the extremely distorted shape of the primary, the relative orbital motion may be notably altered with respect to the two - body purely Keplerian scenario because of non-negligible long - term orbital perturbations affecting, for example, its orbital period. In other words, Kepler 's third law, which holds exactly only for two point - like masses, would no longer be valid for the Regulus system. Regulus A was long thought to be fairly young, only 50 -- 100 million years old, calculated by comparing its temperature, luminosity, and mass. The existence of a white dwarf companion would mean that the system is at least a 1,000 million years old, just to account for the formation of the white dwarf. The discrepancy can be accounted for by a history of mass transfer onto a once - smaller Regulus A. The primary of Regulus A has about 3.5 times the Sun 's mass. It is spinning extremely rapidly, with a rotation period of only 15.9 hours, which causes it to have a highly oblate shape. This results in so - called gravity darkening : the photosphere at Regulus ' poles is considerably hotter, and five times brighter per unit surface area, than its equatorial region. The star 's surface at the equator rotates at about 320 kilometres per second ( 199 miles per second ), or 96.5 % of its critical angular velocity for break - up. It is emitting polarized light because of this. Regulus BC is 5,000 AU from Regulus A. They share a common proper motion and are thought to orbit each other. Designated Regulus B and Regulus C, the pair has Henry Draper Catalogue number HD 87884. The first is a K2V star, while the companion is approximately M4V. The companion pair has an orbital period of about 600 years with a separation of 2.5 '' in 1942. Visibility The Regulus system as a whole is the twenty - first brightest star in the night sky with an apparent magnitude of + 1.35. The light output is dominated by Regulus A. Regulus B, if seen in isolation, would be a binocular object of magnitude + 8.1, and its companion, Regulus C, the faintest of the three stars that has been directly observed, would require a substantial telescope to be seen, at magnitude + 13.5. Regulus A is itself a spectroscopic binary : the secondary star has not yet been directly observed as it is much fainter than the primary. The BC pair lies at an angular distance of 177 arc - seconds from Regulus A, making them visible in amateur telescopes. Etymology and cultural associations Rēgulus is Latin for ' prince ' or ' little king ' ; its Greek equivalent ( Latinised ) is Basiliscus. It is also known as Qalb al - Asad, from the Arabic قلب الأسد, meaning ' the heart of the lion ', a name already attested in the Greek Kardia Leontos whose Latin equivalent is Cor Leōnis. The Arabic phrase is sometimes approximated as Kabelaced. In Chinese it is known as 轩辕 十 四, the Fourteenth Star of Xuanyuan, the Yellow Emperor. In Hindu astronomy, Regulus corresponds to the Nakshatra Magha ( `` the bountiful '' ). Babylonians called it Sharru ( `` the King '' ), and it marked the 15th ecliptic constellation. In India it was known as Maghā ( `` the Mighty '' ), in Sogdiana Magh ( `` the Great '' ), in Persia Miyan ( `` the Centre '' ) and also as Venant, one of the four ' royal stars ' of the Persian monarchy. It was one of the fifteen Behenian stars known to medieval astrologers, associated with granite, mugwort, and the kabbalistic symbol. In MUL. APIN, Regulus is listed as LUGAL, meaning `` the star that stands in the breast of the Lion : the King. '' Regulus through Celestron CGEM DX 1100 @ F6. 3, Canon T3i, Televue 4X Powermate, ISO 800, 30 sec exposure See also Leo constellation Table of stars with Bayer designations Regulus in fiction References ^ Jump up to : van Leeuwen, F. ( 2007 ). `` Validation of the new Hipparcos reduction ''. 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Retrieved 28 July 2016. Jump up ^ `` Occultations of bright stars by planets between 0 and 4000 ''. Retrieved 2007 - 10 - 16. Jump up ^ Sigismondi, Costantino ; Troise, Davide ( 2008 ). `` Asteroidal Occultation of Regulus :. Differential Effect of Light Bending ''. THE ELEVENTH MARCEL GROSSMANN MEETING on Recent Developments in Theoretical and Experimental General Relativity : 2594. Bibcode : 2008mgm... conf. 2594S. doi : 10.1142 / 9789812834300_0469. ISBN 9789812834263. Jump up ^ Sigismondi, C. ; Flatres, T. ; George, T. ; Braga - Ribas, F. ( 2014 ). `` Stellar limb darkening scan during 163 Erigone asteroidal occultation of Regulus on March 20, 2014 at 6 : 06 UT ''. The Astronomer 's Telegram. 5987 : 1. Bibcode : 2014ATel. 5987... 1S. Jump up ^ Regulus 2014 International Occultation Timing Association Jump up ^ Battams, Karl. `` Notable objects in LASCO C3 ''. Sungrazing Comets. Navy.mil. Retrieved 2012 - 09 - 05. Jump up ^ Mason, Brian D. ; Wycoff, Gary L. ; Hartkopf, William I. ; Douglass, Geoffrey G. ; Worley, Charles E. ( 2001 ). `` The 2001 US Naval Observatory Double Star CD - ROM. I. The Washington Double Star Catalog ''. The Astronomical Journal. 122 ( 6 ) : 3466 -- 3471. Bibcode : 2001AJ... 122.3466 M. doi : 10.1086 / 323920. ^ Jump up to : McAlister, H.A. ; ten Brummelaar, T.A. ; Gies ; Huang ; Bagnuolo, Jr. ; Shure ; Sturmann ; Sturmann ; Turner ; Taylor ; Berger ; Baines ; Grundstrom ; Ogden ; Ridgway ; Van Belle ; et al. ( 2005 ). `` First Results from the CHARA Array. I. An Interferometric and Spectroscopic Study of the Fast Rotator Alpha Leonis ( Regulus ) ''. The Astrophysical Journal. 628 : 439 -- 452. arXiv : astro - ph / 0501261. Bibcode : 2005ApJ... 628... 439M. doi : 10.1086 / 430730. Jump up ^ Cotton, Daniel V ; Bailey, Jeremy ; Howarth, Ian D ; Bott, Kimberly ; Kedziora - Chudczer, Lucyna ; Lucas, P. W ; Hough, J. H ( 2017 ). `` Polarization due to rotational distortion in the bright star Regulus ''. Nature Astronomy. Bibcode : 2017NatAs... 1... 690C. doi : 10.1038 / s41550 - 017 - 0238 - 6. Jump up ^ Lindroos, K.P. ( 1985 ). `` A study of visual double stars with early type primaries. IV Astrophysical data ''. Astronomy and Astrophysics Supplement Series. 60 : 183. Bibcode : 1985A&AS... 60... 183L. Jump up ^ Pugh, Philip ( 2009 ). `` Simple Deep Sky Viewing ''. The Science and Art of Using Telescopes. Patrick Moore 's Practical Astronomy Series. p. 157. doi : 10.1007 / 978 - 0 - 387 - 76470 - 2_6. ISBN 978 - 0 - 387 - 76469 - 6. Jump up ^ regulus. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project. ^ Jump up to : Geminus, `` 3.5 '', Introduction to the Phenomena. Jump up ^ βασιλίσκος. Liddell, Henry George ; Scott, Robert ; A Greek -- English Lexicon at the Perseus Project. Jump up ^ καρδία in Liddell and Scott. Jump up ^ Allen, Richard Hinckley ( 1963 ). Star Names : Their Lore and Meaning. Dover. pp. 255 -- 6. ISBN 0 - 486 - 21079 - 0. Jump up ^ Rogers, J.H. ( February 1998 ). `` Origins of the ancient constellations : I. The Mesopotamian traditions ''. Journal of the British Astronomical Association, no. 1. 108 : 9 -- 28. Bibcode : 1998JBAA... 108... 9R. External links Wikimedia Commons has media related to Regulus ( star ). Portrait of a Star on the Edge Egg - Shaped Regulus is Spinning Fast APOD Pictures : Regulus Occulted Regulus & Leo 1 Dwarf Galaxy Bright Star Regulus near the Leo I Dwarf Galaxy Regulus, Mars & Coma Star Cluster `` Regulus 3 ''. SolStation. Retrieved December 1, 2005. Regulus at Constellation Guide Stars of Leo Bayer α ( Regulus ) β ( Denebola ) γ ( Algieba ) δ ( Zosma ) ε ( Algenubi ) ζ ( Adhafera ) η θ ( Chertan ) ι κ ( Al Minliar al Asad ) λ ( Alterf ) μ ( Rasalas ) ν ξ ο ( Subra ) π ρ σ τ υ φ χ ψ ω Flamsteed 6 ( h ) 7 8 9 10 11 12 13 15 ( f ) 18 19 20 21 22 ( g ) 23 26 31 ( A ) 33 34 35 37 39 40 42 43 44 45 46 48 49 50 51 ( m ) 52 ( k ) 53 ( l ) 54 55 56 57 58 ( d ) 59 ( c ) 60 ( b ) 61 ( p ) 62 ( p ) 64 65 ( p ) 66 67 69 ( p ) 71 72 73 ( n ) 75 76 79 80 81 82 83 85 86 87 ( e ) 88 89 90 92 93 95 ( o ) 6 LMi 18 LMi 49 LMi 52 LMi 10 Sex 11 Sex 37 Sex 38 Sex Variable X Y RR RZ SS ST TU TV UV UZ XY XZ AD AM AP AQ CE CW DH DK DN DP DR DX DY EE EO EX GX HN HR 3736 3792 3804 3820 3869 3876 3942 3969 4006 4012 4032 4048 4097 4197 4244 4245 4249 4253 ( p ) 4303 4341 4358 4394 4404 4419 4459 4465 4512 4531 4535 4543 HD 81040 84680 86986 88133 89307 95089 96063 96372 97658 99109 100456 100659 100777 102272 Gliese Gliese 408 Gliese 410 Gliese 436 GJ 3685 Other BD + 20 ° 2457 2MASSI J0937347 + 293142 PG 1031 + 234 PSR B0919 + 06 PSR B0943 + 10 PSR B0950 + 08 PSR B1133 + 16 PSR J1022 + 1001 SDSS J102915 + 172927 WD 1105 - 048 Wolf 359 ( CN ) List Coordinates : 10 08 22.3, + 11 ° 58 ′ 02 '' Retrieved from `` https://en.wikipedia.org/w/index.php?title=Regulus&oldid=823721410 '' Categories : Bayer objects B - type subgiants Multiple star systems Leo ( constellation ) Stars with proper names K - type main - sequence stars M - type main - sequence stars Flamsteed objects Hipparcos objects HR objects Henry Draper Catalogue objects Durchmusterung objects Gliese and GJ objects Hidden categories : Articles containing Ancient Greek - language text All articles with unsourced statements Articles with unsourced statements from May 2015 Talk Contents About Wikipedia Afrikaans Asturianu Azərbaycanca Беларуская Català Čeština Cymraeg Deutsch Ελληνικά Español Esperanto فارسی Français 한국어 हिन्दी Ido Bahasa Indonesia Italiano עברית Basa Jawa Kiswahili Latina Lëtzebuergesch Magyar Македонски Nederlands 日本 語 Norsk Norsk nynorsk پنجابی Polski Português Română Русский Scots Slovenčina Српски / srpski Suomi Svenska தமிழ் Татарча / tatarça Türkçe Українська Tiếng Việt Winaray 中文 Edit links This page was last edited on 3 February 2018, at 00 : 12. 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Question: on what day of the year is the sun near the star regulus (alpha leo)
Answer: August 22