HD 215152

HD 215152 is the Henry Draper Catalogue designation for a star in the zodiac constellation of Aquarius. It has an apparent visual magnitude of 8.13,[2] meaning it is too faint to be seen with the naked eye. Parallax measurements made by the Hipparcos and Gaia spacecraft provide distance estimates of around 70 light years.[1] The star has a relatively high proper motion,[7] moving across the sky at an estimated 0.328 arc seconds per year along a position angle of 205°.[8]

HD 215152
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Aquarius
Right ascension 22h 43m 21.3028s[1]
Declination −06° 24′ 02.953″[1]
Apparent magnitude (V) 8.13[2]
Characteristics
Spectral type K3 V[3]
B−V color index 0.968[4]
Astrometry
Radial velocity (Rv)−13.80[5] km/s
Proper motion (μ) RA: −154.122±0.068[1] mas/yr
Dec.: −289.882±0.062[1] mas/yr
Parallax (π)46.24 ± 0.26[1] mas
Distance70.5 ± 0.4 ly
(21.6 ± 0.1 pc)
Details
Mass0.756±0.016[6] M☉
Surface gravity (log g)4.26±0.15[6] cgs
Temperature4,803±52[6] K
Metallicity [Fe/H]−0.08±0.02[6] dex
Rotational velocity (v sin i)3.35[4] km/s
Age5.207±4.069[6] Gyr
Other designations
BD−07° 5839, GJ 4291, HD 215152, HIP 112190, SAO 146275.[7]
Database references
SIMBADdata

The survey in 2015 have ruled out the existence of any additional stellar companions at projected distances from 6 to 145 astronomical units.[9]

This star has a stellar classification of K3 V,[3] which indicates that it is an ordinary K-type main sequence star. Based upon observation of regular variations in chromospheric activity, it has a rotation period of 36.5±1.6 days.[10] Stellar models give an estimated mass of around 76% of the Sun.[6] It has a slightly lower metallicity than the Sun,[6] and thus has a lower abundance of elements other than hydrogen and helium. The effective temperature of the stellar atmosphere is about 4,803 K, giving it the orange-hued glow of an ordinary K-type star.[11]

HD 215152 is a candidate for possessing a debris disk—a circumstellar disk of orbiting dust and debris. This finding was made through the detection of an infrared excess at a wavelength of 70 μm by the Spitzer Space Telescope. The detection has a 3σ level of certainty.[12]

Planetary system

HD 215152 has a total of four confirmed sub-Neptune mass planets, all of which are probably rocky. With all of the planets orbiting within 0.154 A.U., it is a very close system. The inner two are separated by only 0.0098 A.U., or about four times the distance between the Earth and the Moon. This is unusual for systems discovered by radial velocity measurements.[13] In 2011, it was reported that two planetary candidates (c and d) had been detected in close orbit around this star. The planets were discovered through Doppler spectroscopy using the HARPS spectrograph at La Silla Observatory in Chile. Their presence was revealed by periodic variations in the radial velocity of the host star due to gravitational perturbations by the orbiting objects. In 2018, two more planets were confirmed.[13] All planets have brief orbital periods: the four planets orbit every 5.76, 7.28, 10.86 and 25.2 days respectively.[13] Their probable masses range between 1.7 and 2.9 Earth masses.

Also, there is a gap between orbits of HD 215152 d and HD 215152 e, which may contain fifth, yet-undetected terrestrial low-mass planet.

The HD 215152 planetary system[14]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 1.819+0.501
−0.629 M⊕		 0.057638+0.000739
−0.000759		 5.75999+0.00157
−0.00175		 Probably ≤0.03 — —
c 1.720+0.618
−0.725 M⊕		 0.067393+0.000860
−0.000893		 7.28243+0.00451
−0.00827		 Probably ≤0.03 — —
d 2.801+0.809
−0.923 M⊕		 0.08799+0.00113
−0.00116		 10.86499+0.00564
−0.00613		 Probably ≤0.03 — —
e 2.877+1.063
−1.481 M⊕		 0.15417+0.00199
−0.00204		 25.1967+0.0476
−0.0505		 Probably ≤0.03 — —

References
  1. Brown, A. G. A.; et al. (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy and Astrophysics. 595. A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512.Gaia Data Release 1 catalog entry
  2. Santos, N. C.; et al. (2013), "SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs", Astronomy and Astrophysics, 556, A150, arXiv:1307.0354, Bibcode:2013A&A...556A.150S, doi:10.1051/0004-6361/201321286.
  3. Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal, 126 (4): 2048–2059, arXiv:astro-ph/0308182, Bibcode:2003AJ....126.2048G, doi:10.1086/378365.
  4. Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter", Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725.
  5. Latham, David W.; et al. (August 2002), "A Survey of Proper-Motion Stars. XVI. Orbital Solutions for 171 Single-lined Spectroscopic Binaries", The Astronomical Journal, 124 (2): 1144–1161, Bibcode:2002AJ....124.1144L, doi:10.1086/341384.
  6. Tsantaki, M.; et al. (July 2013), "Deriving precise parameters for cool solar-type stars. Optimizing the iron line list", Astronomy & Astrophysics, 555: A150, arXiv:1304.6639, Bibcode:2013A&A...555A.150T, doi:10.1051/0004-6361/201321103.
  7. "HD 215152 -- High proper-motion Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved March 14, 2016
  8. Carney, Bruce W.; et al. (June 1994), "A survey of proper motion stars. XII. An expanded sample", The Astronomical Journal, 107 (6): 2240–2289, Bibcode:1994AJ....107.2240C, doi:10.1086/117035.
  9. Mugrauer, M.; Ginski, C. (12 May 2015). "High-contrast imaging search for stellar and substellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 450 (3). doi:10.1093/mnras/stv771. Retrieved 19 June 2020.
  10. 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.
  11. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16.
  12. Koerner, D. W.; et al. (February 2010), "New Debris Disk Candidates Around 49 Nearby Stars" (PDF), The Astrophysical Journal Letters, 710 (1): L26–L29, Bibcode:2010ApJ...710L..26K, doi:10.1088/2041-8205/710/1/L26.
  13. Delisle et al., "The HARPS search for southern extra-solar planets", available at arXiv:1802.04631. Accessed 14th Feb. 2018
  14. Mayor, M.; et al. (September 2011), The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets, arXiv:1109.2497, Bibcode:2011arXiv1109.2497M.
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