Astronomy:GQ Lupi

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Short description: Star in the constellation of Lupus
GQ Lupi
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A visual band light curve for GQ Lupi. The main plot (from ASAS data[1]), shows the long-term variability, and the inset plot (adapted from Broeg et al.[2]) shows the short-term periodic brightness variation.
Observation data
{{#ifeq:J2000.0|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000.0      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000.0}}
Constellation Lupus[3]
GQ Lupi A
Right ascension  15h 49m 12.1054s[4]
Declination −35° 39′ 05.058″[4]
Apparent magnitude (V) 11.3–14.3[3]
GQ Lupi C
Right ascension  15h 49m 13.3078s[5]
Declination −35° 39′ 11.761″[5]
Apparent magnitude (V) 19.72[6]
Characteristics
GQ Lupi A
Evolutionary stage Pre-main sequence[7]
Spectral type K7Ve[8]
B−V color index 0.96[9]
Variable type T Tauri variable[3]
GQ Lupi C
Evolutionary stage Pre-main sequence[10]
Spectral type M4[10]
Astrometry
GQ Lupi A
Radial velocity (Rv)−3.6±1.3[11] km/s
Proper motion (μ) RA: −14.133[4] mas/yr
Dec.: −23.329[4] mas/yr
Parallax (π)6.4893 ± 0.0289[4] mas
Distance503 ± 2 ly
(154.1 ± 0.7 pc)
GQ Lupi C
Proper motion (μ) RA: −14.508[5] mas/yr
Dec.: −23.862[5] mas/yr
Parallax (π)5.7229 ± 0.3559[5] mas
Distance570 ± 40 ly
(170 ± 10 pc)
Position (relative to GQ Lupi A)
ComponentGQ Lupi C
Observed separation
(projected)		2430[10] AU {{{projsepref}}}
Details
GQ Lupi A
Mass1.03±0.05[12] M☉
Radius1.75+0.06
−0.07[13] R☉
Luminosity1.05+0.27
−0.22[14] L☉
Surface gravity (log g)3.7[15] cgs
Temperature4306±35[13] K
Rotation8.45±0.20[2] days
Rotational velocity (v sin i)5.66±0.02[16] km/s
Age2.8+1.8
−1.1[14] Myr
GQ Lupi C
Mass0.15±0.05[10] M☉
Radius0.87±0.20[10] R☉
Luminosity0.07±0.02[10] L☉
Temperature3230±101[10] K
Rotational velocity (v sin i)13±6[10] km/s
Other designations
GQ Lup, WDS J15492-3539[17]
GQ Lupi A: CD−35°10525[17]
GQ Lupi C: 2MASS J15491331-3539118[18]
Database references
SIMBADGQ Lupi A
SIMBADGQ Lupi C

GQ Lupi is a possible binary star system in the constellation Lupus. The system is young, with an age of a few million years (for comparison, the Solar System is roughly 4.6 billion years old), and is within the Lupus I star-forming region,[10] which is part of the Scorpius–Centaurus association.[19]

Stellar system

The primary component is designated GQ Lupi A, and was referred to simply as GQ Lupi before the discovery of the secondary stellar companion. It is a T Tauri star, with a variable apparent magnitude ranging from 11.3 at brightest and 14.3 at faintest.[3] The spectral type is K7Ve, with the 'e' indicating emission lines in the spectrum,[8] which in classical T Tauri stars such as GQ Lupi results from an extensive surrounding disk.[3] The star has 1.03 times the mass of the Sun[12] and 1.75 times the Sun's radius, with an effective temperature of 4306 K.[12] Its age is estimated at 2.8+1.8
−1.1 million years.[14] This star is surrounded by a circumstellar disk with a major axis of 59±12 astronomical unit|AU.[12]

In 2020, a low-mass companion of GQ Lupi was discovered at a separation of about 16 arcseconds, or 2400 AU. Designated 2MASS J15491331-3539118 in the 2MASS catalogue, it is a young stellar object that is likely gravitationally bound to the primary star, although the low quality of the companion's proper motion and parallax does not allow for a definitive conclusion. It is estimated to be approximately 15% the Sun's mass and 87% the Sun's radius. It has an effective temperature of about 3230 K, indicating that it is a red dwarf with the spectral type M4.[10]

Substellar companion

VLT NACO image, taken in the Ks-band, of GQ Lupi. The feeble point of light to the right of the star is the newly found cold companion. It is 250 times fainter than the star itself and it located 0.73 arc second west. At the distance of GQ Lupi, this corresponds to a separation of roughly 100 AU. North is up and East is to the left.

In 2005, Ralph Neuhäuser and his colleagues reported a substellar object, GQ Lupi b, orbiting the star. Along with 2M1207b, this was one of the first extrasolar planet candidates to be directly imaged. The image was made with the VLT telescope at Paranal Observatory, Chile, on June 25, 2004. Depending on its mass and the definition of a planet, GQ Lupi b may or may not be considered a planet.[20] As of 2006, the International Astronomical Union Working Group on Extrasolar Planets described GQ Lupi b as a "possible planetary-mass companion to a young star".[21]

The GQ Lupi planetary system
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
b ~10 – 40[16] MJ 97.7+8.9
−7.1[22] 		921+159
−124[lower-alpha 1] 		0.35+0.10
−0.09[22] 		48+4
−5[22]° 		3.7±0.7[14] RJ

Notes

  1. ↑ Calculated using P2 = a3 / Mtot,
    where a is the semi-major axis in astronomical units, Mtot is the total mass of the system, in M☉, and P is the period in years. Upper error bar calculated with the −7.14 uncertainty in a and +0.07 in Mtot. Lower error bar calculated with the +8.92 uncertainty in a and −0.06 in Mtot.

References

  1. ↑ "ASAS All Star Catalogue". The All Sky Automated Survey. https://www.astrouw.edu.pl/asas/?page=aasc. 
  2. ↑ 2.0 2.1 Broeg, C.; Schmidt, T. O. B.; Guenther, E.; Gaedke, A.; Bedalov, A.; Neuhäuser, R.; Walter, F. M. (June 2007). "Rotational period of GQ Lupi" (in en). Astronomy and Astrophysics 468 (3): 1039–1044. doi:10.1051/0004-6361:20066793. ISSN 0004-6361. Bibcode: 2007A&A...468.1039B. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 "VSX : Detail for GQ Lup". https://vsx.aavso.org/index.php?view=detail.top&oid=17792. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  6. ↑ Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series 235 (1): 6. doi:10.3847/1538-4365/aaa1a5. Bibcode: 2018ApJS..235....6T. 
  7. ↑ Ducourant, C.; Teixeira, R.; Périé, J. P.; Lecampion, J. F.; Guibert, J.; Sartori, M. J. (2005). "Pre-main sequence star Proper Motion Catalogue". Astronomy and Astrophysics 438 (2): 769. doi:10.1051/0004-6361:20052788. Bibcode: 2005A&A...438..769D. 
  8. ↑ 8.0 8.1 Herbig, G. H. (June 1977). "Radial velocities and spectral types of T Tauri stars." (in en). The Astrophysical Journal 214: 747–758. doi:10.1086/155304. ISSN 0004-637X. Bibcode: 1977ApJ...214..747H. 
  9. ↑ "V* GQ Lup". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+GQ+Lup. 
  10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 Alcalá, J. M. (2020). "2MASS J15491331-3539118: a new low-mass wide companion of the GQ Lup system". Astronomy & Astrophysics 635: L1. doi:10.1051/0004-6361/201937309. Bibcode: 2020A&A...635L...1A. 
  11. ↑ Frasca, A.; Biazzo, K.; Alcalá, J. M.; Manara, C. F.; Stelzer, B.; Covino, E.; Antoniucci, S. (2017-06-01). "X-shooter spectroscopy of young stellar objects in Lupus - Atmospheric parameters, membership, and activity diagnostics" (in en). Astronomy & Astrophysics 602: A33. doi:10.1051/0004-6361/201630108. ISSN 0004-6361. Bibcode: 2017A&A...602A..33F. 
  12. ↑ 12.0 12.1 12.2 12.3 MacGregor, Meredith A.; Wilner, David J.; Czekala, Ian; Andrews, Sean M.; Dai, Y. Sophia; Herczeg, Gregory J.; Kratter, Kaitlin M.; Kraus, Adam L. et al. (2017-01-16). "ALMA Measurements of Circumstellar Material in the GQ Lup System". The Astrophysical Journal 835 (1): 17. doi:10.3847/1538-4357/835/1/17. ISSN 0004-637X. Bibcode: 2017ApJ...835...17M. 
  13. ↑ 13.0 13.1 Kammerer, J.; Winterhalder, T. O.; Lacour, S.; Stolker, T.; Marleau, G.-D.; Balmer, W. O.; Moore, A. F.; Piscarreta, L. et al. (2025-11-02). "The ExoGRAVITY survey: A K-band spectral library of giant exoplanet and brown dwarf companions". The Astrophysical Journal 704: A318. doi:10.1051/0004-6361/202556860. Bibcode: 2025A&A...704A.318K. 
  14. ↑ 14.0 14.1 14.2 14.3 Xuan, Jerry W.; Hsu, Chih-Chun; Finnerty, Luke; Wang, Jason; Ruffio, Jean-Baptiste; Zhang, Yapeng; Knutson, Heather A.; Mawet, Dimitri et al. (2024-07-01). "Are These Planets or Brown Dwarfs? Broadly Solar Compositions from High-resolution Atmospheric Retrievals of ∼10–30 MJup Companions". The Astrophysical Journal 970 (1): 71. doi:10.3847/1538-4357/ad4796. ISSN 0004-637X. Bibcode: 2024ApJ...970...71X. 
  15. ↑ Donati, J.-F.; Gregory, S. G.; Alencar, S. H. P.; Hussain, G.; Bouvier, J.; Dougados, C.; Jardine, M. M.; Ménard, F. et al. (2012-09-05). "Magnetometry of the classical T Tauri star GQ Lup: non-stationary dynamos and spin evolution of young Suns" (in en). Monthly Notices of the Royal Astronomical Society 425 (4): 2948–2963. doi:10.1111/j.1365-2966.2012.21482.x. ISSN 0035-8711. Bibcode: 2012MNRAS.425.2948D. 
  16. ↑ 16.0 16.1 González Picos, D.; Snellen, I. A. G.; de Regt, S.; Landman, R.; Zhang, Y.; Gandhi, S.; Sánchez-López, A. (January 2025). "The ESO SupJup Survey: IV. Unveiling the carbon isotope ratio of GQ Lup B and its host star". Astronomy & Astrophysics 693: A298. doi:10.1051/0004-6361/202451936. ISSN 0004-6361. Bibcode: 2025A&A...693A.298G. https://www.aanda.org/10.1051/0004-6361/202451936. 
  17. ↑ 17.0 17.1 "GQ Lup". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GQ+Lup. 
  18. ↑ "V* GQ Lup C". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+GQ+Lup+C. 
  19. ↑ Comerón, F. (2008). "The Lupus Clouds" (in en). Handbook of Star Forming Regions, Volume II 5: 295. Bibcode: 2008hsf2.book..295C. 
  20. ↑ Is this a Brown Dwarf or an Exoplanet? New Young Sub-stellar Companion Imaged with the VLT , ESO Press Release 09/05, April 7, 2005. Accessed on line June 13, 2008.
  21. ↑ Lists of Extrasolar Planets , IAU Working Group on Extrasolar Planets, August 28, 2006. Accessed on line June 13, 2008.
  22. ↑ 22.0 22.1 22.2 Venkatesan, Vidya; Blunt, S.; Wang, J. J.; Lacour, S.; Marleau, G.-D.; Coleman, G. A. L.; Guerrero, L.; Balmer, W. O. et al. (2025-10-24). "Constraints on the Orbit of the Young Substellar Companion GQ Lup B from High-resolution Spectroscopy and VLTI/GRAVITY Astrometry". The Astrophysical Journal 993 (1): 69. doi:10.3847/1538-4357/ae0c15. ISSN 0004-637X. Bibcode: 2025ApJ...993...69V. 
  • Guenther, E. W.; Neuhäuser, R.; Wuchterl, G.; Mugrauer, M.; Bedalov, A.; Hauschildt, P. H. (2005). "The low-mass companion of GQ Lup". Astronomische Nachrichten 326 (10): 958–963. doi:10.1002/asna.200510461. Bibcode: 2005AN....326..958G. 
  • Neuhaeuser, Ralph (2005). "Homogeneous comparison of directly detected planet candidates: GQ Lup, 2M1207, AB Pic". arXiv:astro-ph/0509906.
  • Young, Kelly (2005-04-04). "First image of exoplanet orbiting Sun-like star". New Scientist. https://www.newscientist.com/article.ns?id=dn7225. Retrieved 2008-06-09. 
  • "Telescopes see 'distant planet'". BBC News. 2005-04-04. http://news.bbc.co.uk/1/hi/wales/4408187.stm. Retrieved 2008-06-09. 
  • Britt, Robert Roy (2005-04-30). "Fresh Debate over First Photo of Extrasolar Planet". SPACE.com. https://www.space.com/scienceastronomy/050430_exoplanet_image.html. Retrieved 2008-06-09. 



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