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HD 147379

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HD 147379
Location of HD 147379 (circled)
Observation data
Epoch J2000[1]      Equinox J2000[1]
Constellation Draco
HD 147379A
Right ascension 16h 16m 42.74635s
Declination +67° 14′ 19.8316″
Apparent magnitude (V) 8.9[2]
HD 147379B
Right ascension 16h 16m 45.31448s[3]
Declination +67° 15′ 22.4811″[3]
Apparent magnitude (V) 10.69-10.74[4]
Characteristics
HD 147379A
Spectral type M0.0V[2]
B−V color index 1.11[2]
J−H color index 0.643[5]
J−K color index 0.826[5]
HD 147379B
Spectral type M3V[6]
J−H color index 0.608[5]
J−K color index 0.842[5]
Variable type BY Draconis variable[4]
Astrometry
HD 147379A
Radial velocity (Rv)−18.962±0.0011[7] km/s
Proper motion (μ) RA: −497.915[8] mas/yr
Dec.: 84.047[8] mas/yr
Parallax (π)92.8766 ± 0.0146 mas[8]
Distance35.117 ± 0.006 ly
(10.767 ± 0.002 pc)
HD 147379B
Radial velocity (Rv)−18.36±0.0008[9] km/s
Proper motion (μ) RA: −483.006[10] mas/yr
Dec.: 89.049[10] mas/yr
Parallax (π)92.8985 ± 0.0160 mas[10]
Distance35.109 ± 0.006 ly
(10.764 ± 0.002 pc)
Orbit[2]
PrimaryHD 147379A
CompanionHD 147379B
Semi-major axis (a)64.4"
(693.4 AU)
Details[11]
HD 147379A
Mass0.58±0.08 M☉
Radius0.57±0.06 R☉
Luminosity0.1069±0.0153[12] L☉
Surface gravity (log g)4.609±0.012[2] cgs
Temperature4090±50 K
Metallicity [Fe/H]0.16±0.16 dex
Rotation22 d[13]
Age5.1+3.2
−2.4[14] Gyr
HD 147379B
Mass0.45±0.02[6] M☉
Radius0.460±0.008[6] R☉
Luminosity0.02645±0.00645[15] L☉
Surface gravity (log g)4.84±0.06[6] cgs
Temperature3525±31[6] K
Metallicity [Fe/H]0.20±0.10[6] dex
Rotation40.4±3.0 d[6]
Rotational velocity (v sin i)0.50[6] km/s
Other designations
GJ 617, WDS J16167+6714AB
HD 147379A: AG+67° 695, BD+67° 935, Gaia DR3 1642641410934267008, GC 21949, GJ 617 A, HD 147379, HIP 79755, WDS J16167+6714A, G 257-32, G 225-57, G 240-14, LHS 3175, LSPM J1616+6714, LTT 14863, NLTT 42488, TIC 230073581, TYC 4195-721-1, 2MASS J16164280+6714196, WISEA J161641.85+671420.6[1]
HD 147379B: EW Draconis, Gaia DR3 1642642957122493824, GJ 617 B, HD 147379B, HIP 79762, SAO 17026, PPM 19804, WDS J16167+6714B, G 240-15, G 225-58, G 257-33, LHS 3176, LSPM J1616+6715, LTT 14864, NLTT 42489, TIC 230073588, TYC 4195-1167-1, GSC 04195-01167, 2MASS J16164537+6715224, WISEA J161644.44+671523.3[3]
Database references
SIMBADA
B

HD 147379 (Gliese 617) is a wide visual binary between two red dwarfs in the deep northern constellation of Draco. The two stars are located approximately 35.1 light-years (10.8 pc) distant based on Gaia EDR3 parallax measurements, and approaching the Solar System at heliocentric radial velocities of −18.962 km/s and −18.36 km/s, respectively. The brighter primary star, HD 147379A, has an apparent magnitude of 8.9,[2] too faint to be seen by the naked eye from Earth but visible using binoculars.[16] The dimmer secondary, B, fluctuates in apparent magnitude between 10.69 and 10.74,[4] making it observable via a telescope with an aperture of 35 mm or larger.[17]

HD 147379A

[edit]

HD 147379A (HIP 79755) is a red dwarf with a spectral type of M0.0V, about 58% the mass of the Sun, 57% the radius, and an age of 5.1+3.2
−2.4 billion years. It emits just over a tenth of the luminosity of the Sun from its photosphere at an effective temperature of 4,090 K (3,820 °C; 6,900 °F). It has a high metallicity of [Fe/H]=0.16±0.16 dex, meaning it has an iron content somewhere around 45% higher than the Sun.[11] It is also enriched in cobalt, but is depleted in calcium and titanium. The star shows slight variations in the TiO spectral lines.[18]

Planetary system

[edit]

In 2018, two teams independently reported the discovery of an exoplanet orbiting HD 147379A, both via the radial-velocity method.[11][12] This was the first exoplanet found by the CARMENES survey.[11] The planet, commonly referred to as HD 147379 b, has a minimum mass of 21.6 ± 1.1 ME, slightly more massive than Neptune (17.147 ME[19]). It orbits its host star once every 86.58 days at about a third of the distance from Earth to the Sun, placing it within the conservative habitable zone of the star, where liquid water could exist.[2]

One of the teams that discovered HD 147379 b proposed another candidate planet, this one with a minimum mass of 27 ME and a 500-day period, orbiting at a distance of about 1 AU.[12] However, a 2023 follow-up study did not detect such a signal. Instead, they detected a signal with a 12.3-day period, but discarded it due to the high chance of it being a false positive. Nevertheless, it is highly likely that a second planet exists interior to b's orbit.[2]

The HD 147379A planetary system[2]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥21.6 ± 1.1 M🜨 0.3315 ± 0.0024[20] 86.58 ± 0.14 0.0630+0.0470
−0.0380 		— —

HD 147379B

[edit]

HD 147379B (HIP 79762) is a gravitationally bound companion to HD 147379A at a separation of 64.4 arcseconds, which corresponds to a distance of 693.4 AU.[2]

This is a red dwarf with a spectral type of M3V, about 45% the mass of the Sun and 46% the radius. It has a "partially convective" structure, meaning that the outer convection zone does not reach down to the core,[6] as opposed to "fully convective" stars weighing less than 0.35 M☉ that are convective throughout.[21] It too has a high metallicity of [M/H]=0.20±0.10 dex, translating to a roughly 60% excess in elements heavier than hydrogen and helium compared to the Sun. At an effective temperature of 3,525 K (3,252 °C; 5,885 °F),[6] it radiates just 2.6% the luminosity of the Sun from its photosphere.[15] It rotates on its axis once every 40.4 days at a relatively slow projected equatorial velocity of 0.50 km/s.[6]

It has a magnetic field that fluctuated in strength between 36-75 G between 2020-2022, approximately 100 times stronger than Earth's magnetic field (0.22-0.67 G[22]) and similar to those of faster-rotating red dwarfs. The variations in strength are smaller than those seen in fully convective red dwarfs such as Gliese 1151.[6]

In 1994, the star was reported to have a high likelihood (99%) of exhibiting long-term variability, albeit the author noted that this may be suspect.[23] It was formally classified as a BY Draconis variable in 1997, receiving the variable-star designation EW Draconis.[4]

References

[edit]
  1. ^ a b "HD 147379". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 January 2025.
  2. ^ a b c d e f g h i j Stalport, M.; Cretignier, M.; Udry, S.; et al. (2023). "A review of planetary systems around HD 99492, HD 147379, and HD 190007 with HARPS-N" (PDF). Astronomy & Astrophysics. 678: A90. arXiv:2308.05669. Bibcode:2023A&A...678A..90S. doi:10.1051/0004-6361/202346887. ISSN 0004-6361. Retrieved 2 January 2025.
  3. ^ a b c "HD 147379B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 January 2025.
  4. ^ a b c d Kazarovets, E. V.; Samus, N. N. (23 April 1997). "The 73rd Name-List of Variable Stars". Information Bulletin on Variable Stars. 4471: 1–45. Bibcode:1997IBVS.4471....1K.
  5. ^ a b c d Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; et al. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  6. ^ a b c d e f g h i j k l Lehmann, L T; Donati, J-F; Fouqué, P; et al. (9 November 2023). "SPIRou reveals unusually strong magnetic fields of slowly rotating M dwarfs" (PDF). Monthly Notices of the Royal Astronomical Society. 527 (2): 4330–4352. doi:10.1093/mnras/stad3472. ISSN 0035-8711. Retrieved 16 January 2025.
  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. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  9. ^ Fouqué, Pascal; Moutou, Claire; Malo, Lison; et al. (1 April 2018). "SPIRou Input Catalogue: global properties of 440 M dwarfs observed with ESPaDOnS at CFHT" (PDF). Monthly Notices of the Royal Astronomical Society. 475 (2): 1960–1986. arXiv:1712.04490. doi:10.1093/mnras/stx3246. ISSN 0035-8711. Retrieved 17 January 2025.
  10. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  11. ^ a b c d Reiners, A.; Ribas, I.; Zechmeister, M.; et al. (2018). "The CARMENES search for exoplanets around M dwarfs: HD147379 b: A nearby Neptune in the temperate zone of an early-M dwarf" (PDF). Astronomy & Astrophysics. 609: L5. arXiv:1712.05797. Bibcode:2018A&A...609L...5R. doi:10.1051/0004-6361/201732165. ISSN 0004-6361. Retrieved 2 January 2025.
  12. ^ a b c Hobson, M. J.; Díaz, R. F.; Delfosse, X.; et al. (2018). "The SOPHIE search for northern extrasolar planets: XIII. Two planets around M-dwarfs Gl617A and Gl96" (PDF). Astronomy & Astrophysics. 618: A103. arXiv:1806.10958. Bibcode:2018A&A...618A.103H. doi:10.1051/0004-6361/201832732. ISSN 0004-6361. Retrieved 2 January 2025.
  13. ^ Pepper, Joshua (1 January 2018). "Rotational Period Measurement of Planet Host HD 147379". Research Notes of the AAS. 2 (1): 14. arXiv:1801.01789. Bibcode:2018RNAAS...2...14P. doi:10.3847/2515-5172/aaa842. ISSN 2515-5172.
  14. ^ Veyette, Mark J.; Muirhead, Philip S. (20 August 2018). "Chemo-kinematic Ages of Eccentric-planet-hosting M Dwarf Stars". The Astrophysical Journal. 863 (2): 166. arXiv:1807.06017. Bibcode:2018ApJ...863..166V. doi:10.3847/1538-4357/aad40e. ISSN 0004-637X.
  15. ^ a b Stassun, Keivan G.; Oelkers, Ryan J.; Paegert, Martin; et al. (1 October 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256.
  16. ^ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011.
  17. ^ North, Gerald; James, Nick (2014). Observing Variable Stars, Novae and Supernovae. Cambridge University Press. p. 24. ISBN 978-1-107-63612-5.
  18. ^ Zboril, M. (21 July 2009). "Metallicity and photospheric abundances in field GKM giants and dwarfs" (PDF). Monthly Notices of the Royal Astronomical Society. 397 (1): 335–340. Bibcode:2009MNRAS.397..335Z. doi:10.1111/j.1365-2966.2009.14917.x. Retrieved 20 January 2025.
  19. ^ Williams, David R. (1 September 2004). "Neptune Fact Sheet". NASA. Archived from the original on 1 July 2010. Retrieved 14 August 2007.
  20. ^ Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A.; et al. (1 July 2021). "The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades". The Astrophysical Journal Supplement Series. 255 (1): 8. arXiv:2105.11583. Bibcode:2021ApJS..255....8R. doi:10.3847/1538-4365/abe23c. ISSN 0067-0049.
  21. ^ Reiners, Ansgar; Basri, Gibor (March 2009). "On the magnetic topology of partially and fully convective stars". Astronomy and Astrophysics. 496 (3): 787–790. arXiv:0901.1659. Bibcode:2009A&A...496..787R. doi:10.1051/0004-6361:200811450. S2CID 15159121.
  22. ^ "An Overview of the Earth's Magnetic Field". www.geomag.bgs.ac.uk. Retrieved 2 March 2024.
  23. ^ Weis, Edward W. (1994). "Long term variability in dwarf M stars". The Astronomical Journal. 107: 1135. Bibcode:1994AJ....107.1135W. doi:10.1086/116925.
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