Gliese 752

Gliese 752 is a binary star system in the Aquila constellation. This system is relatively nearby, at a distance of about 19 light years.[6] This system consists of two M-type stars. The primary star is the magnitude 9 Gliese (GJ) 752 A. The secondary star is the dim magnitude 17 Gliese (GJ) 752 B, more commonly referred to as VB 10. This stellar pair form a binary star system separated by about 74 arc seconds (~434 AU).[8] This system is also known for its high proper motion of about 1 arc second a year.

Gliese 752
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Gliese 752 A
Right ascension  19h 16m 55.257s[1]
Declination +05° 10′ 08.05″[1]
Apparent magnitude (V) ~9.13[1]
Gliese 752 B
Right ascension  19h 16m 57.62s[2]
Declination +05° 09′ 02.2″[2]
Apparent magnitude (V) ~17.30[2]
Characteristics
Gliese 752 A
Spectral type M2.5[1]
Apparent magnitude (B) ~10.63[1]
Apparent magnitude (V) ~9.13[1]
Apparent magnitude (R) ~8.3[1]
Apparent magnitude (J) ~5.58[1]
Apparent magnitude (H) ~4.93[1]
Apparent magnitude (K) ~4.67[1]
Variable type BY[3]
Gliese 752 B
Spectral type M8V[2]
Apparent magnitude (B) ~19.42[2]
Apparent magnitude (V) ~17.30[2]
Apparent magnitude (R) ~15.6[2]
Apparent magnitude (J) 9.908 ± 0.025[2]
Apparent magnitude (H) 9.226 ± 0.026[2]
Apparent magnitude (K) 8.765 ± 0.022[2]
Variable type UV[4]
Astrometry
A
Proper motion (μ) RA: −579[5] mas/yr
Dec.: −1333[5] mas/yr
Parallax (π)169.1590 ± 0.0520[5] mas
Distance19.281 ± 0.006 ly
(5.912 ± 0.002 pc)
Absolute magnitude (MV)10.13[6]
B
Proper motion (μ) RA: −598[7] mas/yr
Dec.: −1365[7] mas/yr
Parallax (π)168.9620 ± 0.1299[7] mas
Distance19.30 ± 0.01 ly
(5.918 ± 0.005 pc)
Absolute magnitude (MV)18.7[8]
Details
Gliese 752 A
Mass0.46[6] M☉
Radius0.546[6] R☉
Luminosity (bolometric)0.0326 ± 0.0004[9] L☉
Temperature~3,240[6] K
Metallicity–0.05 ± 0.17[10]
Rotation46.5±0.3 d[11]
Gliese 752 B
Mass0.075 ±.05[12] M☉
Radius~0.102[6] R☉
Temperature~2,600[6] K
Age~1[12] Gyr
Other designations
BD+04° 4048, GJ 752, CCDM J19169+0510, WDS J19169+0510
Gliese 752 A: V1428 Aql, HD 180617, HIP 94761, Ross 652, Wolf 1055, TYC 472-1252-1, GSC 00472-01252, 2MASS J19165526+0510086[1]
Gliese 752 B: VB 10, V1298 Aql, 2MASS J19165762+0509021[2]
Database references
SIMBADAB
A
vB 10 (B)

In August 2018, a group of scientist using measurements taken from the CARMENES spectrograph, on the Calar Alto Observatory located in Spain, announced they had detected a planet orbiting the larger of the stars, HD 180617 (Gliese 752 A). The measurements indicated the presence of a planet with a minimum mass comparable to Neptune on an orbit partly located within the habitable zone.[9]

The name and number are from the Catalogue of Nearby Stars, published by German astronomer Wilhelm Gliese in 1969.[13]

Interior dynamics of the Gliese 752 stars
Diagram showing the relative sizes and internal dynamic processes of the two Gliese 752 stars.

Before the Hubble Space Telescope observation of Gliese 752 system, astronomers thought magnetic fields in stars required the same dynamo process that creates magnetic fields on the Sun. In the classic solar model heat generated by nuclear fusion reactions at the star's center escapes through a radiative zone just outside the core. The heat travels from the radiative core to the star's surface through a convection zone. In this region, heat bubbles to the surface by motions similar to boiling in a pot of water.

Dynamos, which accelerate electrons to create magnetic forces, operate when the interior of a star rotates faster than its surface. Recent studies of the Sun indicate its convection zone rotates at nearly the same rate at all depths. This means the solar dynamo must operate in the more rapidly rotating radiative core just below the convective zone.[14]

Gliese 752 A characteristics

The primary star, also known as Wolf 1055, is a type M2.5 red dwarf with about half the size and mass as the Sun and considerably cooler at 3240 K. This star was first observed to be a high proper motion star by the German astronomer Max Wolf with his pioneering use of astrophotography. He added this star to his extensive catalog of such stars in 1919.[15] It is a variable star with the variable star catalog name V1428 Aquilae. It is a BY Draconis type variable star subject to flare events.[1][3]

Planetary system
The HD 180617 (Gliese 752 A) planetary system[9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥12.2+1.0
−1.4[note 1] M⊕		 ≥0.3357+0.0099
−0.0100[note 1]		 ≥105.9+0.09
−0.10[note 1]		 0.16+0.05
−0.10		 ≈0 [note 1]° —

Gliese 752 B characteristics
Main article: VB 10

Gliese 752 was not known to be a binary star system until the discovery of a small dim secondary star by George Van Biesbroeck in 1944. This star is identified as VB 10 in Van Biesbroeck's star catalog. This star is notable for its very low mass. At .08 solar mass it is near the lower mass limit for a star. It is also quite small at 10% of the solar radius.[8]

This star is a type M8V red dwarf. This star is also known for its very low luminosity, with an absolute magnitude of nearly 19, due to its very cool surface temperature of only 2600°K.[2] It is a variable star with the variable star catalog name V1298 Aquilae. This star is a UV Ceti type variable star also subject to flare events. It shares the large proper motion, along with the tendency to flare, with the primary star.[4]

In 2009 the discovery of the extrasolar planet, VB 10b, was announced in orbit around this star.[12] However a subsequent spectrographic survey failed to confirm the presence of any large planets in orbit around this star.[16]

See also

Notes
  1. Under the condition of an edge-on view onto the system, the semi-amplitude astrometric signature at Earth’s distance is estimated to be about 4.6 μas. With decreasing orbital inclination, the planetary mass and therefore the astrometric signature increases, so this is only a lower limit.

References
  1. "V* V1428 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-05-30.
  2. "V* V1298 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-05-28.
  3. "V1428 Aql". General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2009-06-06.
  4. "V1298 Aql". General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2009-05-28.
  5. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  6. Linsky, Jeffrey L.; Wood, Brian E.; Brown, Alexander; Giampapa, Mark S.; Ambruster, Carol (December 20, 1995). "Stellar Activity at the End of the Main Sequence: GHRS Observations of the M8 Ve Star VB 10". The Astrophysical Journal. 455: 670–676. Bibcode:1995ApJ...455..670L. doi:10.1086/176614. hdl:2060/19970022983.
  7. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  8. van Biesbroeck, G. (August 1944). "The star of lowest known luminosity". The Astronomical Journal. 51: 61–62. Bibcode:1944AJ.....51...61V. doi:10.1086/105801.
  9. Kaminski, A; et al. (2018). "The CARMENES search for exoplanets around M dwarfs. A Neptune-mass planet traversing the habitable zone around HD 180617". Astronomy & Astrophysics. A115: 618. arXiv:1808.01183. doi:10.1051/0004-6361/201833354.
  10. Rojas-Ayala, Bárbara; et al. (April 2012). "Metallicity and Temperature Indicators in M Dwarf K-band Spectra: Testing New and Updated Calibrations with Observations of 133 Solar Neighborhood M Dwarfs" (PDF). The Astrophysical Journal. 748 (2): 93. arXiv:1112.4567. Bibcode:2012ApJ...748...93R. doi:10.1088/0004-637X/748/2/93. See table 3.
  11. Suárez Mascareño, A.; et al. (September 2015), "Rotation periods of late-type dwarf stars from time series high-resolution spectroscopy of chromospheric indicators", Monthly Notices of the Royal Astronomical Society, 452 (3): 2745–2756, arXiv:1506.08039, Bibcode:2015MNRAS.452.2745S, doi:10.1093/mnras/stv1441.
  12. Pravdo; et al. (June 2009). "An Ultracool Star's Candidate Planet" (PDF). The Astrophysical Journal. 700 (1): 623–632. arXiv:0906.0544. Bibcode:2009ApJ...700..623P. doi:10.1088/0004-637X/700/1/623. Archived from the original (PDF) on 2009-06-04. Retrieved 2009-05-30.
  13. Gliese, W. (1969). "Catalogue of Nearby Stars. Edition 1969". Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg. 22. Verlag G. Braun, Karlsruhe, 117 Seiten. 22: 1. Bibcode:1969VeARI..22....1G.CS1 maint: location (link)
  14. "Red Dwarf Dynamo Raises Puzzle over Interiors of Lowest Mass Stars". hubblesite. 1995-01-10. Retrieved 2009-08-03.
  15. Wolf, M. (August 1919). "Starkbewegter Stern in Aquila". Astronomische Nachrichten. 209 (4): 61–62. Bibcode:1919AN....209...61W. doi:10.1002/asna.19192090406.
  16. Bean, Jacob; Andreas Seifahrt; Henrik Hartman; Hampus Nilsson; Ansgar Reiners; Stefan Dreizler; Henry; Guenter Wiedemann (2009). "The CRIRES Search for Planets Around the Lowest-Mass Stars. II. No Giant Planet Orbiting VB10". arXiv:0912.0003v1 [astro-ph.EP].

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