Astronomy:Lacaille 9352
Template:Requested move notice
Coordinates: 
23h 05m 52.03604s, −35° 51′ 11.0475″
  Lacaille 9352 Location of Lacaille 9352 in the constellation Piscis Austrinus | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Piscis Austrinus[1]: 84 |
| Right ascension | 23h 05m 52.03579s[2] |
| Declination | −35° 51′ 11.0552″[2] |
| Apparent magnitude (V) | 7.34[3] |
| Characteristics | |
| Spectral type | M0.5V[4] |
| U−B color index | +1.18[3] |
| B−V color index | +1.50[3] |
| Variable type | Suspected[5] |
| Astrometry | |
| Radial velocity (Rv) | +8.31±0.13[2] km/s |
| Proper motion (μ) | RA: +6,765.995[2] mas/yr Dec.: +1,330.285[2] mas/yr |
| Parallax (π) | 304.1354 ± 0.0200[2] mas |
| Distance | 10.7241 ± 0.0007 ly (3.2880 ± 0.0002 pc) |
| Absolute magnitude (MV) | 9.8[6] |
| Details | |
| Mass | 0.479+0.011 −0.010[7] M☉ |
| Radius | 0.474±0.008[7] R☉ |
| Luminosity | 0.0368±0.0006[7] L☉ |
| Habitable zone inner limit | 0.16[8] AU |
| Habitable zone outer limit | 0.40[8] AU |
| Surface gravity (log g) | 4.78[9] cgs |
| Temperature | 3,672+36 −34[7] K |
| Metallicity [Fe/H] | −0.22±0.09[10] dex |
| Rotation | 38.7±0.5 d[11] |
| Rotational velocity (v sin i) | 1[12] km/s |
| Age | 4.57[13] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
Lacaille 9352 (Lac 9352), also commonly called Gliese 887 (GJ 887), is a red dwarf star in the southern constellation of Piscis Austrinus. With an apparent visual magnitude of 7.34,[3] this star is too faint to be viewed with the naked eye except possibly under excellent seeing conditions. Parallax measurements place it at a distance of about 10.72 light-years (3.29 parsecs) from Earth.[2] It is the twelfth closest star system to the Solar System[16] and is the closest star in the constellation Piscis Austrinus.[1]: 84 Its closest neighbour is the EZ Aquarii triple star system at about 4.1 ly away.
Properties
.svg)
This star has the fourth highest known proper motion,[17] (which was first noticed by Benjamin Gould in 1881[18]) moving a total of 6.9 arcseconds per year. However, this is still a very small movement overall, as there are 3,600 arcseconds in a degree of arc. The space velocity components of this star are (U, V, W) = (−93.9, −14.1, −51.4) km/s.[19] If the radial velocity (Vr) equals +9.7 km/s then about 2,700 years ago Lacaille 9352 was at its minimal distance of approximately 10.63 ly (3.26 pc) from the Sun.[20]
The spectrum of Lacaille 9352 places it at a stellar classification of M0.5V,[4] indicating it is a type of main sequence star known as a red dwarf. This was the first red dwarf star to have its angular diameter measured,[21] with the physical diameter being about 47% of the Sun's radius.[7] It has around half the mass of the Sun[4] and the outer envelope has an effective temperature of about 3,670 K.[7]
Planetary system
In June 2020, two super-Earth planets were reported, as well as a third candidate planet with a period of 50.7 days, located within the habitable zone. They were detected using the radial velocity method from observations with HARPS in Chile and HIRES in Hawaii.[22][23] A 2026 follow-up study confirmed the 50-day planet and detected a fourth, Earth-mass planet closer to the star. A fifth candidate signal is also suspected.[11] The habitable-zone planet, GJ 887 d, is the second-nearest known exoplanet in the habitable zone after Proxima Centauri b, though it is significantly more massive than Earth and its composition is unknown. It may be possible to characterize it with proposed direct imaging missions such as the Habitable Worlds Observatory.[11]
Additionally, the star presents a difference in proper motion measurements taken by the Hipparcos and Gaia spacecraft, suggesting the possible presence of an outer giant planet.[8]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| f (unconfirmed) | ≥ 0.47±0.11 M⊕ | 0.0263±0.0009 | 2.2166±0.0001 | — | — | — |
| e | ≥ 1.46+0.19 −0.18 M⊕ |
0.0417+0.0014 −0.0015 |
4.4249±0.0001 | — | — | — |
| b | ≥ 3.9±0.5 M⊕ | 0.0683+0.0022 −0.0024 |
9.2619±0.0005 | 0.14±0.06 | — | — |
| c | ≥ 6.5+1.0 −0.9 M⊕ |
0.121+0.004 −0.005 |
21.784±0.004 | 0.17±0.06 | — | — |
| d | ≥ 6.1±1.4 M⊕ | 0.212+0.007 −0.008 |
50.77±0.05 | 0.25+0.20 −0.15[22] |
— | — |
See also
- List of nearest stars
- Lalande 21185
References
- ↑ 1.0 1.1 Kirkpatrick, J. Davy et al. (April 2024). "The Initial Mass Function Based on the Full-sky 20 pc Census of ~3600 Stars and Brown Dwarfs". The Astrophysical Journal Supplement Series 271 (2): 55. doi:10.3847/1538-4365/ad24e2. Bibcode: 2024ApJS..271...55K.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 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.
- ↑ 3.0 3.1 3.2 3.3 Cousins, A. W. J. (1973). "UBV photometry of some southern stars". Monthly Notes of the Astronomical Society of Southern Africa 32: 11. Bibcode: 1973MNSSA..32...11C.
- ↑ 4.0 4.1 4.2 Demory, Brice-Olivier; Ségransan, Damien; Forveille, Thierry; Queloz, Didier; Beuzit, Jean-Luc; Delfosse, Xavier; Di Folco, Emmanuel; Kervella, Pierre et al. (October 2009). "Mass-radius relation of low and very low-mass stars revisited with the VLTI". Astronomy and Astrophysics 505 (1): 205–215. doi:10.1051/0004-6361/200911976. Bibcode: 2009A&A...505..205D.
- ↑ Micela, G.; Pye, J.; Sciortino, S. (April 1997). "Coronal properties of nearby old disk and halo dM stars". Astronomy and Astrophysics 320: 865–877. Bibcode: 1997A&A...320..865M.
- ↑ Murdin, Paul, ed (November 2000). Encyclopedia of Astronomy and Astrophysics. Bristol: Institute of Physics Publishing. doi:10.1888/0333750888/5158. ISBN 0333750888. Bibcode: 2000eaa..bookE5158.. "absolute magnitude is 9.8".
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Pineda, J. Sebastian et al. (September 2021). "The M-dwarf Ultraviolet Spectroscopic Sample. I. Determining Stellar Parameters for Field Stars". The Astrophysical Journal 918 (1): 23. doi:10.3847/1538-4357/ac0aea. 40. Bibcode: 2021ApJ...918...40P.
- ↑ 8.0 8.1 8.2 Painter, Katie E.; Bowler, Brendan P.; Franson, Kyle; Becker, Juliette C.; Burt, Jennifer A. (2025-06-26). "Astrometric Accelerations of Provisional Targets for the Habitable Worlds Observatory". The Astronomical Journal 170 (3): 147. doi:10.3847/1538-3881/ade442. Bibcode: 2025AJ....170..147P.
- ↑ Rabus, Markus; Lachaume, Régis; Jordán, Andrés; Brahm, Rafael; Boyajian, Tabetha; Von Braun, Kaspar; Espinoza, Néstor; Berger, Jean-Philippe et al. (2019). "A discontinuity in the Teff–radius relation of M-dwarfs". Monthly Notices of the Royal Astronomical Society 484 (2): 2674–2683. doi:10.1093/mnras/sty3430. Bibcode: 2019MNRAS.484.2674R.
- ↑ López-Morales, Mercedes (May 2007). "On the Correlation between the Magnetic Activity Levels, Metallicities, and Radii of Low-Mass Stars". The Astrophysical Journal 660 (1): 732–739. doi:10.1086/513142. Bibcode: 2007ApJ...660..732L.
- ↑ 11.0 11.1 11.2 11.3 Hartogh, C. et al. (January 2026). "RedDots: Multiplanet system around M dwarf GJ 887 in the solar neighborhood". Astronomy & Astrophysics forthcoming. doi:10.1051/0004-6361/202554984.
- ↑ Torres, G. R. et al. (December 2006). "Search for associations containing young stars (SACY). I. Sample and searching method". Astronomy and Astrophysics 460 (3): 695–708. doi:10.1051/0004-6361:20065602. Bibcode: 2006A&A...460..695T.
- ↑ Yee, Samuel W.; Petigura, Erik A.; von Braun, Kaspar (2017). "Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library". The Astrophysical Journal 836 (1): 77. doi:10.3847/1538-4357/836/1/77. Bibcode: 2017ApJ...836...77Y.
- ↑ "LACAILLE 9352 -- Pre-main sequence Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+217987.
- ↑ Luyten, Willem Jacob; Shapley, Harlow (1930). "A study of the near-by stars". Annals of the Astronomical Observatory of Harvard College 85 (5): 73. Bibcode: 1930AnHar..85...73L.
- ↑ Reylé, Céline; Jardine, Kevin; Fouqué, Pascal; Caballero, Jose A.; Smart, Richard L.; Sozzetti, Alessandro (30 April 2021). "The 10 parsec sample in the Gaia era". Astronomy & Astrophysics 650: A201. doi:10.1051/0004-6361/202140985. Bibcode: 2021A&A...650A.201R. Data available at https://gruze.org/10pc/
- ↑ "High Proper Motion Stars in the Hipparcos Catalogue". European Space Agency. July 1, 2007. http://www.rssd.esa.int/index.php?project=HIPPARCOS&page=hpm.
- ↑ Gould, B. A. (1881). "Corrigenda in the Uranometria Argentina. Star with large proper motion". Astronomische Nachrichten 100 (1): 7–10. doi:10.1002/asna.18811000104. Bibcode: 1881AN....100....7G. https://zenodo.org/record/1424713.
- ↑ "ARICNS star page of Lacaille 9352". Astronomisches Rechen-Institut Heidelberg. http://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01887.htm.
- ↑ "Annotations on NAME LACAILLE 9352 object". SIMBAD. Centre de Données astronomiques de Strasbourg. http://cdsannotations.u-strasbg.fr/annotations/simbadObject/1191721.
- ↑ Glindemann, Andreas; Paresce, Francesco. "Giant Eyes for the VLT Interferometer". European Southern Observatory. http://www.eso.org/public/news/eso0134/.
- ↑ 22.0 22.1 Jeffers, S. V.; Dreizler, S.; Barnes, J. R.; Haswell, C. A.; Nelson, R. P.; Rodríguez, E.; López-González, M. J.; Morales, N. et al. (2020), "A multiple planet system of super-Earths orbiting the brightest red dwarf star GJ887", Science 368 (6498): 1477–1481, doi:10.1126/science.aaz0795, PMID 32587019, Bibcode: 2020Sci...368.1477J
- ↑ Witze, Alexandra (2020). "Why boring could be good for this star's two intriguing planets". Nature. doi:10.1038/d41586-020-01905-5. PMID 34168349. https://www.nature.com/articles/d41586-020-01905-5. Retrieved 2020-06-30.
 |
