Astronomy:HD 147379

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Short description: Visual binary in constellation Draco
HD 147379
Location of HD 147379 (circled)
Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}}
Constellation Draco[1][2]
HD 147379A
Right ascension  16h 16m 42.74635s[3]
Declination +67° 14′ 19.8316″[3]
Apparent magnitude (V) 8.9[4]
HD 147379B
Right ascension  16h 16m 45.31448s[5]
Declination +67° 15′ 22.4811″[5]
Apparent magnitude (V) 10.69-10.74[6]
Characteristics
HD 147379A
Evolutionary stage main sequence[3]
Spectral type M0.0V[4]
B−V color index 1.11[4]
J−H color index 0.643[7]
J−K color index 0.826[7]
HD 147379B
Spectral type M3V[8]
J−H color index 0.608[7]
J−K color index 0.842[7]
Variable type BY Draconis variable[6]
Astrometry
HD 147379A
Radial velocity (Rv)−18.962±0.0011[9] km/s
Proper motion (μ) RA: −497.915[3] mas/yr
Dec.: 84.047[3] mas/yr
Parallax (π)92.8766 ± 0.0146[3] mas
Distance35.117 ± 0.006 ly
(10.767 ± 0.002 pc)
Absolute magnitude (MV)+8.47[1]
HD 147379B
Radial velocity (Rv)−18.36±0.0008[10] km/s
Proper motion (μ) RA: −483.006[5] mas/yr
Dec.: 89.049[5] mas/yr
Parallax (π)92.8985 ± 0.0160[5] mas
Distance35.109 ± 0.006 ly
(10.764 ± 0.002 pc)
Absolute magnitude (MV)+10.54[2]
Orbit[4]
PrimaryHD 147379A
CompanionHD 147379B
Semi-major axis (a)64.4"
(693.4 astronomical unit|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[4] 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[8] M☉
Radius0.460±0.008[8] R☉
Luminosity0.02645±0.00645[15] L☉
Surface gravity (log g)4.84±0.06[8] cgs
Temperature3525±31[8] K
Rotation40.4±3.0 d[8]
Rotational velocity (v sin i)0.50[8] km/s
Other designations
GJ 617, HD 147379, WDS J16167+6714
HD 147379A: BD+67°935, GC 21949, HIP 79755, G 257-32, G 225-57, G 240-14, LHS 3175, LSPM J1616+6714, LTT 14863, NLTT 42488, TYC 4195-721-1, 2MASS J16164280+6714196[16]
HD 147379B: EW Draconis, HIP 79762, SAO 17026, PPM 19804, G 240-15, G 225-58, G 257-33, LHS 3176, LSPM J1616+6715, LTT 14864, NLTT 42489, TYC 4195-1167-1, GSC 04195-01167, 2MASS J16164537+6715224[17]
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 DR3 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,[4] too faint to be seen by the naked eye from Earth but visible using binoculars.[18] The dimmer secondary, B, fluctuates in apparent magnitude between 10.69 and 10.74,[6] making it observable via a telescope with an aperture of 35 mm or larger.[19]

HD 147379A

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.[20]

Planetary system

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 M⊕, slightly more massive than Neptune (17.147 M⊕[21]). 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.[4]

One of the teams that discovered HD 147379 b proposed another candidate planet, this one with a minimum mass of 27 M⊕ 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.[4]

The HD 147379A planetary system[4]
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[22] 86.58 ± 0.14 0.0630+0.0470−0.0380 — —

HD 147379B

A red-light light curve plotted from ZTF data[23]

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.[4]

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,[8] as opposed to "fully convective" stars weighing less than 0.35 M☉ that are convective throughout.[24] 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),[8] 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.[8]

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[25]) 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.[8]

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.[26] It was formally classified as a BY Draconis variable in 1997, receiving the variable-star designation EW Draconis.[6]

References

  1. ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 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.
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 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". Astronomy & Astrophysics 678: A90. doi:10.1051/0004-6361/202346887. ISSN 0004-6361. Bibcode: 2023A&A...678A..90S. 
  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. ↑ 6.0 6.1 6.2 6.3 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. 
  7. ↑ 7.0 7.1 7.2 7.3 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. 
  8. ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 Lehmann, L T; Donati, J-F; Fouqué, P et al. (2023-11-09). "SPIRou reveals unusually strong magnetic fields of slowly rotating M dwarfs". Monthly Notices of the Royal Astronomical Society 527 (2): 4330–4352. doi:10.1093/mnras/stad3472. ISSN 0035-8711. 
  9. ↑ Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  10. ↑ Fouqué, Pascal; Moutou, Claire; Malo, Lison et al. (2018-04-01). "SPIRou Input Catalogue: global properties of 440 M dwarfs observed with ESPaDOnS at CFHT". Monthly Notices of the Royal Astronomical Society 475 (2): 1960–1986. doi:10.1093/mnras/stx3246. ISSN 0035-8711. Bibcode: 2018MNRAS.475.1960F. 
  11. ↑ 11.0 11.1 11.2 11.3 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". Astronomy & Astrophysics 609: L5. doi:10.1051/0004-6361/201732165. ISSN 0004-6361. Bibcode: 2018A&A...609L...5R. 
  12. ↑ 12.0 12.1 12.2 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". Astronomy & Astrophysics 618: A103. doi:10.1051/0004-6361/201832732. ISSN 0004-6361. Bibcode: 2018A&A...618A.103H. 
  13. ↑ Pepper, Joshua (2018-01-01). "Rotational Period Measurement of Planet Host HD 147379". Research Notes of the AAS 2 (1): 14. doi:10.3847/2515-5172/aaa842. ISSN 2515-5172. Bibcode: 2018RNAAS...2...14P. 
  14. ↑ Veyette, Mark J.; Muirhead, Philip S. (2018-08-20). "Chemo-kinematic Ages of Eccentric-planet-hosting M Dwarf Stars". The Astrophysical Journal 863 (2): 166. doi:10.3847/1538-4357/aad40e. ISSN 0004-637X. Bibcode: 2018ApJ...863..166V. 
  15. ↑ 15.0 15.1 Stassun, Keivan G.; Oelkers, Ryan J.; Paegert, Martin et al. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256. Bibcode: 2019AJ....158..138S. 
  16. ↑ "HD 147379". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+147379. 
  17. ↑ "HD 147379B". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+147379B. 
  18. ↑ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars". Cloudy Nights. http://www.cloudynights.com/documents/limiting.pdf. 
  19. ↑ North, Gerald; James, Nick (2014). Observing Variable Stars, Novae and Supernovae. Cambridge University Press. p. 24. ISBN 978-1-107-63612-5. https://books.google.com/books?id=IzoDBAAAQBAJ&pg=PA24. 
  20. ↑ Zboril, M. (2009-07-21). "Metallicity and photospheric abundances in field GKM giants and dwarfs". Monthly Notices of the Royal Astronomical Society 397 (1): 335–340. doi:10.1111/j.1365-2966.2009.14917.x. Bibcode: 2009MNRAS.397..335Z. 
  21. ↑ Williams, David R. (1 September 2004). "Neptune Fact Sheet". NASA. http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html. 
  22. ↑ Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A. et al. (2021-07-01). "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. doi:10.3847/1538-4365/abe23c. ISSN 0067-0049. Bibcode: 2021ApJS..255....8R. 
  23. ↑ "NASA/IPAC Infrared Science Archive". NASA. https://irsa.ipac.caltech.edu/frontpage/. 
  24. ↑ Reiners, Ansgar; Basri, Gibor (March 2009). "On the magnetic topology of partially and fully convective stars". Astronomy and Astrophysics 496 (3): 787–790. doi:10.1051/0004-6361:200811450. Bibcode: 2009A&A...496..787R. 
  25. ↑ "An Overview of the Earth's Magnetic Field". http://www.geomag.bgs.ac.uk/education/earthmag.html#_Toc2075549. 
  26. ↑ Weis, Edward W. (1994). "Long term variability in dwarf M stars". The Astronomical Journal 107: 1135. doi:10.1086/116925. Bibcode: 1994AJ....107.1135W. 



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