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Gliese 521
Observation data; Epoch J2000 Equinox J2000
Constellation	Canes Venatici
Right ascension	13h 39m 24.10228s
Declination	+46° 11′ 11.3631″
Apparent magnitude (V)	+10.26
Characteristics
Spectral type	M1V
Apparent magnitude (J)	7.05
Apparent magnitude (H)	6.51
Apparent magnitude (K)	6.26
Astrometry
Radial velocity (Rv)	−65.72±0.15 km/s
Proper motion (μ)	RA: −42.332±0.012 mas/yr ; Dec.: 389.167±0.014 mas/yr
Parallax (π)	74.7985 ± 0.0153 mas
Distance	43.605 ± 0.009 ly ; (13.369 ± 0.003 pc)
Absolute magnitude (MV)	10.243
Details
Mass	0.506±0.021 M☉; 0.47±0.05 M☉
Radius	0.619±0.030 R☉; 0.47±0.05 R☉
Luminosity	0.033+0.008; −0.007 L☉
Surface gravity (log g)	4.79±0.04 cgs
Temperature	3,493±50 K
Metallicity [Fe/H]	−0.34 dex; −0.09±0.09 dex
Rotation	49.5±3.5 d
Rotational velocity (v sin i)	0.85 km/s
Other designations
	BD+46 1889, GJ 521, HIP 66625, SAO 44697, WDS 13394+4611, LTT 13979, TYC 3463-00063-1, 2MASS J13392410+4611114
Database references
SIMBAD	data

Gliese 521 is a double star in the northern constellation of Canes Venatici. The system is located at a distance of 43.6 light-years from the Sun based on parallax measurements, but is drawing closer with a radial velocity of −65.6 km/s.^[4] It is predicted to come as close as 15.70 light-years from the Sun in 176,900 years.^[8] This star is too faint to be visible to the naked eye, having an apparent visual magnitude of +10.26^[2] and an absolute magnitude of 10.24.^[4]

The primary is an M-type main-sequence star with a stellar classification of M1V.^[3] It is only about half the size and mass of the Sun. The star is rotating slowly with a projected rotational velocity of 0.85 km/s^[4] and a rotation period of roughly 49.5 days.^[6] The star has a lower metal-content compared to the Sun. It is radiating just 3%^[5] of the luminosity of the Sun from its photosphere at an effective temperature of 3,493 K.^[4]

A faint stellar companion was announced by E. Jódar and associates in 2013. The companion has an angular separation of 521 mas along a position angle of 352.1°±1.4° from the primary. This is equivalent to a projected separation of 7.24±0.14 AU.^[9]

Search for planets

According to Marcy & Benitz (1989)^[10] detected a possible periodicity of 510 days, inferring the possible presence of a massive planetary object with minimum mass of 12 times that of Jupiter in highly eccentric orbit (e=0.6). So far the planet has not been confirmed. A radial velocity study of the star during the period 2013–2017 initially found a promising signal, but this disappeared when additional data was collected and was instead attributed to magnetic activity.^[11]

References

^ ^a ^b ^c ^d ^e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^a ^b ^c ^d ^e ^f ^g Jenkins, J. S.; et al. (2009). "Rotational Velocities for M Dwarfs". The Astrophysical Journal. 704 (2): 975. arXiv:0908.4092. Bibcode:2009ApJ...704..975J. doi:10.1088/0004-637X/704/2/975. S2CID 119203469.
^ ^a ^b Alonso-Floriano, F. J.; et al. (May 2015). "CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS". Astronomy & Astrophysics. 577: 19. arXiv:1502.07580. Bibcode:2015A&A...577A.128A. doi:10.1051/0004-6361/201525803. S2CID 53135130. A128.
^ ^a ^b ^c ^d ^e ^f ^g ^h Houdebine, E. R. (September 2010). "Observation and modelling of main-sequence star chromospheres - XIV. Rotation of dM1 stars". Monthly Notices of the Royal Astronomical Society. 407 (3): 1657–1673. Bibcode:2010MNRAS.407.1657H. doi:10.1111/j.1365-2966.2010.16827.x.
^ ^a ^b ^c ^d ^e ^f Maldonado, J.; et al. (February 2017). "HADES RV Programme with HARPS-N at TNG . III. Flux-flux and activity-rotation relationships of early-M dwarfs". Astronomy & Astrophysics. 598: 19. arXiv:1610.05906. Bibcode:2017A&A...598A..27M. doi:10.1051/0004-6361/201629223. A27.
^ ^a ^b Suárez Mascareño, A.; et al. (April 2018). "HADES RV programme with HARPS-N at TNG. VII. Rotation and activity of M-dwarfs from time-series high-resolution spectroscopy of chromospheric indicators". Astronomy & Astrophysics. 612: 17. arXiv:1712.07375. Bibcode:2018A&A...612A..89S. doi:10.1051/0004-6361/201732143. A89.
^ "BD+46 1889". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-21.
^ Bailer-Jones, C. A. L. (January 2018). "The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release". Astronomy & Astrophysics. 609: 16. arXiv:1708.08595. Bibcode:2018A&A...609A...8B. doi:10.1051/0004-6361/201731453. S2CID 119462489. A8.
^ Jódar, Esther; et al. (February 2013). "New companions to nearby low-mass stars". Monthly Notices of the Royal Astronomical Society. 429 (1): 859–867. Bibcode:2013MNRAS.429..859J. doi:10.1093/mnras/sts382.
^ Marcy, Geoffrey W.; Benitz, Karsten J. (September 1989). "A search for substellar companions to low-mass stars". Astrophysical Journal, Part 1. 344 (1): 441–453. Bibcode:1989ApJ...344..441M. doi:10.1086/167812.
^ Gonzalez Alvarez, Ester (2018). Planets around low-mass stars and stellar activity effects. Università degli Studi di Palermo. hdl:10447/265375. Retrieved 2021-11-21. {{cite book}}: |work= ignored (help)