# 2 Lupi

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Star in the constellation Lupus

2 Lupi Location of 2 Lupi (circled in red) Observation data Epoch J2000 Equinox J2000 Constellation Lupus Right ascension 15h 17m 49.83809s[1] Declination −30° 08′ 55.2165″[1] Apparent magnitude (V) 4.33[2] Characteristics Evolutionary stage giant Spectral type K0 IIIa CH-1[3] B−V color index 1.100±0.004[4] Variable type none[5] Astrometry Radial velocity (Rv) −2.91±0.15[6] km/s Proper motion (μ) RA: −10.16[1] mas/yr Dec.: −3.66[1] mas/yr Parallax (π) 10.01±0.21 mas[1] Distance 326 ± 7 ly (100 ± 2 pc) Absolute magnitude (MV) −0.65[4] Details Radius 11.0+0.7 −0.8[6] R☉ Luminosity 65.6±0.8[6] L☉ Surface gravity (log g) 2.84[2] cgs Temperature 4,953+197 −148[6] K Metallicity [Fe/H] 0.11[2] dex Other designations f Lupi, 2 Lup, NSV 7012, CD−29°11630, FK5 3207, HD 135758, HIP 74857, HR 5686, SAO 183346[7] Database references SIMBAD data

**2 Lupi,** also known by its Bayer designation *f Lupi*, is a solitary[8][star](/source/Star) in the [southern](/source/Southern_celestial_hemisphere) [constellation](/source/Constellation) of [Lupus](/source/Lupus_(constellation)),[7] situated approximately 326 [light-years](/source/Light-year) away from the [Sun](/source/Sun).[1] It has the [Bayer designation](/source/Bayer_designation) **f Lupi**; *2 Lupi* is the [Flamsteed designation](/source/Flamsteed_designation). It is visible to the naked eye as a faint, orange-hued star with an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.33.[2] It is moving closer to the Earth with a heliocentric [radial velocity](/source/Radial_velocity) of −3 km/s.[6]

This is an aging [giant star](/source/Giant_star) with a [stellar classification](/source/Stellar_classification) of K0 IIIa CH-1.[3] The suffix notation indicates abnormally [weak lines](/source/Absorption_line) of [carbyne](/source/Carbyne). Having exhausted the hydrogen at its [core](/source/Stellar_core), the star [evolved](/source/Stellar_evolution) away from the [main sequence](/source/Main_sequence) by expanding to 11[6] times the [Sun's radius](/source/Sun's_radius). The star is radiating 65.6[6] times the [luminosity of the Sun](/source/Luminosity_of_the_Sun) from its enlarged [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 4,953 [K](/source/Kelvin).[6]

2 Lupi is also moving steadily toward our solar system at a rate of roughly –3 km/s. This slow approach is observable through its measured radial velocity.[9]

## References

1. ^ [***a***](#cite_ref-vanLeeuwen2007_1-0) [***b***](#cite_ref-vanLeeuwen2007_1-1) [***c***](#cite_ref-vanLeeuwen2007_1-2) [***d***](#cite_ref-vanLeeuwen2007_1-3) [***e***](#cite_ref-vanLeeuwen2007_1-4) [***f***](#cite_ref-vanLeeuwen2007_1-5) van Leeuwen, F. (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-McWilliam1990_2-0) [***b***](#cite_ref-McWilliam1990_2-1) [***c***](#cite_ref-McWilliam1990_2-2) [***d***](#cite_ref-McWilliam1990_2-3) McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", *Astrophysical Journal Supplement Series*, **74**: 1075–1128, [Bibcode](/source/Bibcode_(identifier)):[1990ApJS...74.1075M](https://ui.adsabs.harvard.edu/abs/1990ApJS...74.1075M), [doi](/source/Doi_(identifier)):[10.1086/191527](https://doi.org/10.1086%2F191527)

1. ^ [***a***](#cite_ref-perkins1989_3-0) [***b***](#cite_ref-perkins1989_3-1) Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", *Astrophysical Journal Supplement Series*, **71**: 245, [Bibcode](/source/Bibcode_(identifier)):[1989ApJS...71..245K](https://ui.adsabs.harvard.edu/abs/1989ApJS...71..245K), [doi](/source/Doi_(identifier)):[10.1086/191373](https://doi.org/10.1086%2F191373)

1. ^ [***a***](#cite_ref-Anderson2012_4-0) [***b***](#cite_ref-Anderson2012_4-1) Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", *Astronomy Letters*, **38** (5): 331, [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971), [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A), [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015), [S2CID](/source/S2CID_(identifier)) [119257644](https://api.semanticscholar.org/CorpusID:119257644).

1. **[^](#cite_ref-Samus2017_5-0)** Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", *Astronomy Reports*, 5.1, **61** (1): 80–88, [Bibcode](/source/Bibcode_(identifier)):[2017ARep...61...80S](https://ui.adsabs.harvard.edu/abs/2017ARep...61...80S), [doi](/source/Doi_(identifier)):[10.1134/S1063772917010085](https://doi.org/10.1134%2FS1063772917010085), [S2CID](/source/S2CID_(identifier)) [125853869](https://api.semanticscholar.org/CorpusID:125853869).

1. ^ [***a***](#cite_ref-GaiaDR2_6-0) [***b***](#cite_ref-GaiaDR2_6-1) [***c***](#cite_ref-GaiaDR2_6-2) [***d***](#cite_ref-GaiaDR2_6-3) [***e***](#cite_ref-GaiaDR2_6-4) [***f***](#cite_ref-GaiaDR2_6-5) [***g***](#cite_ref-GaiaDR2_6-6) [***h***](#cite_ref-GaiaDR2_6-7) [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. ([Gaia collaboration](/source/Data_Processing_and_Analysis_Consortium)) (August 2018). ["*Gaia* Data Release 2: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F201833051). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **616**. A1. [arXiv](/source/ArXiv_(identifier)):[1804.09365](https://arxiv.org/abs/1804.09365). [Bibcode](/source/Bibcode_(identifier)):[2018A&A...616A...1G](https://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201833051](https://doi.org/10.1051%2F0004-6361%2F201833051). [Gaia DR2 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20DR2%201443435089669339648) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Simbad_7-0) [***b***](#cite_ref-Simbad_7-1) ["2 Boo"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=2+Boo). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2019-04-06.

1. **[^](#cite_ref-Eggleton2008_8-0)** Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*, **389** (2): 869–879, [arXiv](/source/ArXiv_(identifier)):[0806.2878](https://arxiv.org/abs/0806.2878), [Bibcode](/source/Bibcode_(identifier)):[2008MNRAS.389..869E](https://ui.adsabs.harvard.edu/abs/2008MNRAS.389..869E), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2008.13596.x](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x), [S2CID](/source/S2CID_(identifier)) [14878976](https://api.semanticscholar.org/CorpusID:14878976).

1. **[^](#cite_ref-9)** ["2 Lupi - Star in Lupus | TheSkyLive"](https://theskylive.com/sky/stars/2-lupi-star). *theskylive.com*. Retrieved 2025-08-19.

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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