# RU Lupi

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Star in the constellation of Lupus

RU Lupi A broad-band optical light curve for RU Lupi, adapted from Siwak et al. (2016)[1] Observation data Epoch J2000.0 Equinox J2000.0 Constellation Lupus Right ascension 15h 56m 42.31154s[2] Declination −37° 49′ 15.5021″[2] Apparent magnitude (V) 10.519[3] Characteristics Spectral type K7/M0e[4] U−B color index –0.802[3] B−V color index +0.476[3] Variable type T Tauri-type Astrometry Radial velocity (Rv) −6.4[5] km/s Proper motion (μ) RA: −10.61[2] mas/yr Dec.: −26.41[2] mas/yr Parallax (π) 6.3489±0.0402 mas[6] Distance 514 ± 3 ly (157.5 ± 1.0 pc) Details Mass 0.6–0.7[7] M☉ Radius 1.64[7] R☉ Luminosity 2.1[8] L☉ Surface gravity (log g) 3.9[7] cgs Temperature 3,950[9] K Rotational velocity (v sin i) 9[10] km/s Age 2–3[7] Myr Other designations RU Lup, CD−37°10602, HIP 78094, HD 142560[4] Database references SIMBAD data

**RU Lupi** is a star in the [constellation](/source/Constellation) of [Lupus](/source/Lupus_(constellation)), located in the young [Lupus Star Forming Region](https://en.wikipedia.org/w/index.php?title=Lupus_Star_Forming_Region&action=edit&redlink=1). Based on [parallax](/source/Parallax) measurements, the distance to this star is about 514 light-years (158 pc). The [apparent visual magnitude](/source/Apparent_visual_magnitude) is 10.5,[3] so viewing it would require a telescope with an [aperture](/source/Aperture) of 6 cm (2 in), but preferably larger.[11]

This is a [T Tauri star](/source/T_Tauri_star), which is a stage that a newly formed, low-mass star passes through before settling down onto the [main sequence](/source/Main_sequence), where it will generate all of its energy through hydrogen [fusion](/source/Nuclear_fusion) at its core. The age of this star is about 2–3 million years.[7] It is showing random fluctuations in luminosity, including variations in ultraviolet and X-ray emissions.[12]

The [spectrum](/source/Stellar_spectrum) of the star is displaying [emission lines](/source/Emission_line) of hydrogen overlaid on the star's normal spectra.[12] This may be caused by the impact of infalling gas on the star's outer envelope, combined with the signature of a strong outflowing [wind](/source/Stellar_wind) near the star.[13] Mass is accreting onto the star at the rate of about (5 ± 2) × 10−8 times the mass of the Sun per year.[7]

RU Lupi has an estimated mass of 0.6–0.7 times the [mass of the Sun](/source/Solar_mass) and 1.6 times the [Sun's radius](/source/Solar_radius).[7] It is radiating more than double the luminosity of the Sun, at an [effective temperature](/source/Effective_temperature) of about 3,950 K.[9] RU Lupi is surrounded by a circumstellar disk of dust that has a combined mass of up to 0.032 times the mass of the Sun. The particles in the disk vary in size, but range up to a centimeter in cross-section.[8]

The star exhibits periodic [radial velocity](/source/Radial_velocity) variations that are attributed to [stellar spots](/source/Starspot) on the surface of the star, based on the correlation between the radial velocity and the bisector inverse slope (a quantity that parametrises the shape of the spectral lines). The time period of the variations makes it unlikely that they are caused by [stellar pulsations](/source/Stellar_pulsations) as these would be expected to occur on much shorter timescales (hours rather than days), and the correlation with the bisector inverse slope makes it unlikely that an orbiting companion is responsible as reflex motion would not cause the line profile variations.[12]

## References

1. **[^](#cite_ref-Siwak2016_1-0)** Siwak, Michal; Ogloza, Waldemar; Rucinski, Slavek M.; Moffat, Anthony F. J.; Matthews, Jaymie M.; Cameron, Chris; Guenther, David B.; Kuschnig, Rainer; Rowe, Jason F.; Sasselov, Dimitar; Weiss, Werner W. (March 2016). ["Stable and unstable accretion in the classical T Tauri stars IM Lup and RU Lup as observed by MOST"](https://doi.org/10.1093%2Fmnras%2Fstv2848). *Monthly Notices of the Royal Astronomical Society*. **456** (4): 3972–3984. [arXiv](/source/ArXiv_(identifier)):[1512.01992](https://arxiv.org/abs/1512.01992). [Bibcode](/source/Bibcode_(identifier)):[2016MNRAS.456.3972S](https://ui.adsabs.harvard.edu/abs/2016MNRAS.456.3972S). [doi](/source/Doi_(identifier)):[10.1093/mnras/stv2848](https://doi.org/10.1093%2Fmnras%2Fstv2848).

1. ^ [***a***](#cite_ref-aaa474_2_653_2-0) [***b***](#cite_ref-aaa474_2_653_2-1) [***c***](#cite_ref-aaa474_2_653_2-2) [***d***](#cite_ref-aaa474_2_653_2-3) van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", *Astronomy and Astrophysics*, **474** (2): 653–664, [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357), [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600).

1. ^ [***a***](#cite_ref-saaoc9_55_3-0) [***b***](#cite_ref-saaoc9_55_3-1) [***c***](#cite_ref-saaoc9_55_3-2) [***d***](#cite_ref-saaoc9_55_3-3) Kilkenny, D.; et al. (1985), "Optical and infrared photometry of southern early-type shell stars and pre-main-sequence variables", *South African Astronomical Observatory Circular*, **9** (9): 55–86, [Bibcode](/source/Bibcode_(identifier)):[1985SAAOC...9...55K](https://ui.adsabs.harvard.edu/abs/1985SAAOC...9...55K)

1. ^ [***a***](#cite_ref-SIMBAD_4-0) [***b***](#cite_ref-SIMBAD_4-1) ["HD 142560 -- Variable Star of Orion Type"](http://simbad.u-strasbg.fr/simbad/sim-id?Ident=RU+Lupi), *SIMBAD*, Centre de Données astronomiques de Strasbourg, [archived](https://web.archive.org/web/20201118034644/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=RU+Lupi) from the original on 2020-11-18, retrieved 2012-01-12

1. **[^](#cite_ref-gcsrv_5-0)** Wilson, Ralph Elmer (1953). "General Catalogue of Stellar Radial Velocities". *Carnegie Institute Washington D.C. Publication*. Washington: Carnegie Institution of Washington. [Bibcode](/source/Bibcode_(identifier)):[1953GCRV..C......0W](https://ui.adsabs.harvard.edu/abs/1953GCRV..C......0W).

1. **[^](#cite_ref-6)** [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. (Gaia collaboration) (2021). ["*Gaia* Early Data Release 3: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202039657). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **649**: A1. [arXiv](/source/ArXiv_(identifier)):[2012.01533](https://arxiv.org/abs/2012.01533). [Bibcode](/source/Bibcode_(identifier)):[2021A&A...649A...1G](https://ui.adsabs.harvard.edu/abs/2021A&A...649A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202039657](https://doi.org/10.1051%2F0004-6361%2F202039657). [S2CID](/source/S2CID_(identifier)) [227254300](https://api.semanticscholar.org/CorpusID:227254300). (Erratum: [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202039657e](https://doi.org/10.1051%2F0004-6361%2F202039657e)). [Gaia EDR3 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20EDR3%206010114558131195392) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-aj129_6_2777_7-0) [***b***](#cite_ref-aj129_6_2777_7-1) [***c***](#cite_ref-aj129_6_2777_7-2) [***d***](#cite_ref-aj129_6_2777_7-3) [***e***](#cite_ref-aj129_6_2777_7-4) [***f***](#cite_ref-aj129_6_2777_7-5) [***g***](#cite_ref-aj129_6_2777_7-6) Herczeg, Gregory J.; et al. (2005), "The Loopy Ultraviolet Line Profiles of RU Lupi: Accretion, Outflows, and Fluorescence", *[The Astronomical Journal](/source/The_Astronomical_Journal)*, **129** (6): 2777–2791, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0504654](https://arxiv.org/abs/astro-ph/0504654), [Bibcode](/source/Bibcode_(identifier)):[2005AJ....129.2777H](https://ui.adsabs.harvard.edu/abs/2005AJ....129.2777H), [doi](/source/Doi_(identifier)):[10.1086/430075](https://doi.org/10.1086%2F430075), [S2CID](/source/S2CID_(identifier)) [1181710](https://api.semanticscholar.org/CorpusID:1181710)

1. ^ [***a***](#cite_ref-aaa495_3_869_8-0) [***b***](#cite_ref-aaa495_3_869_8-1) Lommen, D.; et al. (March 2009), "Large grains in discs around young stars: ATCA observations of WW Chamaeleontis, RU Lupi, and CS Chamaeleontis", *Astronomy and Astrophysics*, **495** (3): 869–879, [arXiv](/source/ArXiv_(identifier)):[0812.3849](https://arxiv.org/abs/0812.3849), [Bibcode](/source/Bibcode_(identifier)):[2009A&A...495..869L](https://ui.adsabs.harvard.edu/abs/2009A&A...495..869L), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:200810999](https://doi.org/10.1051%2F0004-6361%3A200810999), [S2CID](/source/S2CID_(identifier)) [6837972](https://api.semanticscholar.org/CorpusID:6837972)

1. ^ [***a***](#cite_ref-aaa391_2_595_9-0) [***b***](#cite_ref-aaa391_2_595_9-1) Stempels, H. C.; Piskunov, N. (2002), "Spectroscopy of T Tauri stars with UVES. Observations and analysis of RU Lup", *[Astronomy and Astrophysics](/source/Astronomy_and_Astrophysics)*, **391** (2): 595–608, [Bibcode](/source/Bibcode_(identifier)):[2002A&A...391..595S](https://ui.adsabs.harvard.edu/abs/2002A&A...391..595S), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20020814](https://doi.org/10.1051%2F0004-6361%3A20020814)

1. **[^](#cite_ref-aaa461_1_253_10-0)** Stempels, H. C.; Gahm, G. F.; Petrov, P. P. (January 2007), "Periodic radial velocity variations in RU Lupi", *Astronomy and Astrophysics*, **461** (1): 253–259, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0611560](https://arxiv.org/abs/astro-ph/0611560), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...461..253S](https://ui.adsabs.harvard.edu/abs/2007A&A...461..253S), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20065268](https://doi.org/10.1051%2F0004-6361%3A20065268), [S2CID](/source/S2CID_(identifier)) [14162626](https://api.semanticscholar.org/CorpusID:14162626)

1. **[^](#cite_ref-sherrod_koed2003_11-0)** Sherrod, P. Clay; Koed, Thomas L. (2003), [*A Complete Manual of Amateur Astronomy: Tools and Techniques for Astronomical Observations*](https://books.google.com/books?id=4zjv84hHNPcC&pg=PA9), Astronomy Series, Courier Dover Publications, p. 9, [ISBN](/source/ISBN_(identifier)) [0-486-42820-6](https://en.wikipedia.org/wiki/Special:BookSources/0-486-42820-6)

1. ^ [***a***](#cite_ref-aaa461_1_461_12-0) [***b***](#cite_ref-aaa461_1_461_12-1) [***c***](#cite_ref-aaa461_1_461_12-2) Stempels, H. C.; Gahm, G. F.; Petrov, P. P. (2007). "Periodic radial velocity variations in RU Lupi". *[Astronomy and Astrophysics](/source/Astronomy_and_Astrophysics)*. **461** (1): 253–259. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0611560](https://arxiv.org/abs/astro-ph/0611560). [Bibcode](/source/Bibcode_(identifier)):[2007A&A...461..253S](https://ui.adsabs.harvard.edu/abs/2007A&A...461..253S). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20065268](https://doi.org/10.1051%2F0004-6361%3A20065268). [S2CID](/source/S2CID_(identifier)) [14162626](https://api.semanticscholar.org/CorpusID:14162626).

1. **[^](#cite_ref-aaa480_2_421_13-0)** Podio, L.; et al. (March 2008), "Tracing the origins of permitted emission lines in RU Lupi down to AU scales", *Astronomy and Astrophysics*, **480** (2): 421–430, [arXiv](/source/ArXiv_(identifier)):[0711.2596](https://arxiv.org/abs/0711.2596), [Bibcode](/source/Bibcode_(identifier)):[2008A&A...480..421P](https://ui.adsabs.harvard.edu/abs/2008A&A...480..421P), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078694](https://doi.org/10.1051%2F0004-6361%3A20078694), [S2CID](/source/S2CID_(identifier)) [13892816](https://api.semanticscholar.org/CorpusID:13892816)

v t e Constellation of Lupus List of stars in Lupus Lupus in Chinese astronomy Stars Bayer α (Uridim) β γ δ ε ζ η θ ι κ λ μ ν1 ν2 ξ ο π ρ σ τ1 τ2 υ φ1 φ2 χ ψ1 ψ2 ω Flamsteed 1 (i) 2 (f) Variable RU EX GG GQ HR II IL IM KT (d) V407 V462 HR 5362 5364 5401 5651 (e) 5724 (k) 5825 (g) 5943 5967 HD 134004 135344 136164 141943 142527 143811 Other Gliese 588 HIP 70849 Lupus-TR-3 SSSPM J1549−3544 WASP-132 Exoplanets GQ Lupi b HIP 70849 b Lupus-TR-3b WASP-178b Star clusters NGC 5749 NGC 5822 NGC 5824 NGC 5927 NGC 5986 Nebulae IC 4406 NGC 5882 Galaxies IC 4444 NGC 5530 NGC 5643 Astronomical events SN 1006 Category

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Adapted from the Wikipedia article [RU Lupi](https://en.wikipedia.org/wiki/RU_Lupi) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/RU_Lupi?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.