HD 171028

Star in the constellation Ophiuchus

HD 171028
Observation data Epoch J2000.0 Equinox J2000.0
Constellation	Ophiuchus
Right ascension	18^h 32^m 15.4933^s^[1]
Declination	06° 56′ 44.6858″^[1]
Apparent magnitude (V)	8.301^[2]
Characteristics
Spectral type	G0^[3]
B−V color index	0.61^[3]
Astrometry

Radial velocity (R_v)	+13.48±0.28^[1] km/s
Proper motion (μ)	RA: −42.869±0.084^[1] mas/yr Dec.: −14.705±0.077^[1] mas/yr
Parallax (π)	8.9274 ± 0.0497 mas^[1]
Distance	365 ± 2 ly (112.0 ± 0.6 pc)

Details

Mass	1.01±0.06^[2] `M`_☉
Radius	2.42+0.01 −0.03^[1] `R`_☉
Luminosity	5.406+0.042 −0.041^[1] `L`_☉
Surface gravity (log g)	3.84±0.03^[2] cgs
Temperature	5,671±16^[2] K
Metallicity [Fe/H]	−0.48±0.01^[2] dex
Rotational velocity (v sin i)	2.3^[3] km/s
Age	4.890±0.229^[4] Gyr

Other designations
BD+06 3833, TYC 458-1450-1, 2MASS J18321548+0656446^[5]
Database references
SIMBAD	data

HD 171028 is a star with an exoplanet companion in the equatorial constellation of Ophiuchus. With an apparent visual magnitude of 8.3,^[2] it is too faint to be readily visible with the naked eye. Unlike most planet-harboring stars, it does not have a Hipparcos number. The star is located at a distance of approximately 365 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13.5 km/s.^[1]

This is a yellow-hued G-type star of unknown luminosity class with a stellar classification of G0.^[3] It is a metal-poor star belonging to the thin disk population.^[6] HD 171028 is estimated to be nearly five billion years old and is spinning with a projected rotational velocity of 2.3 km/s.^[3] It has the same mass as the Sun, but the radius is 2.4 times larger. The star is radiating 5.4^[1] times the luminosity of the Sun from its photosphere at an effective temperature of 5,671 K.^[2]

In the summer of 2007, a Jovian planetary companion was discovered by the HARPS planet search program using the radial velocity method.^[3] This object is orbiting at a distance of 1.32 AU from the host star with a period of 1.5 years and an eccentricity (ovalness) of 0.59. Since the inclination of the orbit is unknown, only a minimum mass can be determined. This planet has at least double the mass of Jupiter.^[7]

The HD 171028 planetary system^[7]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥1.98 M_J	1.32	550±3	0.59±0.01	—	—

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j 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.
^ ^a ^b ^c ^d ^e ^f ^g Sousa, S. G.; et al. (February 2011). "Spectroscopic characterization of a sample of metal-poor solar-type stars from the HARPS planet search program. Precise spectroscopic parameters and mass estimation". Astronomy and Astrophysics. 526: 11. arXiv:1012.1528. Bibcode:2011A&A...526A..99S. doi:10.1051/0004-6361/201015646. S2CID 118785170. A99.
^ ^a ^b ^c ^d ^e ^f Santos, N. C.; et al. (2007). "The HARPS search for southern extra-solar planets. XII. A giant planet orbiting the metal-poor star HD 171028". Astronomy and Astrophysics. 474 (2): 647–651. arXiv:0708.0954. Bibcode:2007A&A...474..647S. doi:10.1051/0004-6361:20078129. S2CID 73681862.
^ Costa Silva, A. R.; et al. (February 2020). "Chemical abundances of 1111 FGK stars from the HARPS-GTO planet search sample. III. Sulfur". Astronomy & Astrophysics. 634: 10. arXiv:1912.08659. Bibcode:2020A&A...634A.136C. doi:10.1051/0004-6361/201936523. S2CID 209405391. A136.
^ "HD 171028". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-10-06.
^ Haywood, M. (May 2008). "A peculiarity of metal-poor stars with planets?". Astronomy and Astrophysics. 482 (2): 673–676. arXiv:0804.2954. Bibcode:2008A&A...482..673H. doi:10.1051/0004-6361:20079141. S2CID 16390388.
^ ^a ^b Santos, Nuno C.; et al. (2011), "The HARPS search for southern extrasolar planets XXV. Results from the metal-poor sample", Astronomy and Astrophysics, 526: A112, arXiv:1011.2094, Bibcode:2011A&A...526A.112S, doi:10.1051/0004-6361/201015494, S2CID 119106340

Constellation of Ophiuchus

Stars

Bayer	α (Rasalhague) β (Cebalrai) γ δ (Yed Prior) ε (Yed Posterior) ζ (Han) η (Sabik) θ ι κ λ (Marfik) μ ν ξ ο ρ σ τ υ φ χ ψ ω
Flamsteed	12 14 15 16 18 19 20 21 23 24 26 28 29 30 31 36 (A, Guniibuu) 37 38 41 43 44 (b) 45 (d, θ Tel) 50 51 (c) 52 53 (f) 54 58 61 66 67 68 70 (p) 71 72 73 74 24 Sco
Variable	U V X Y RS RV RZ ST SW TT TW UU WZ XX BF IX KK V380 V426 V438 V442 V445 V451 V453 V502 V508 V566 V567 V716 V839 V841 V849 V986 V1010 V1054 V2051 V2052 V2076 V2105 V2112 V2113 V2114 V2118 V2126 V2129 V2213 V2214 V2247 V2291 V2292 V2293 V2295 V2301 V2306 V2307 V2324 V2368 V2388 V2393 V2400 V2487 V2500 (Barnard's Star) V2502 V2540 V2542
HR	5989 5990 6041 6067 6096 6124 6136 6137 6140 6144 6179 6189 6190 6193 6201 6202 6235 6248 6269 6284 6294 6296 6302 6308 6329 6340 6350 6353 6354 6358 6359 6361 6365 6367 6372 6375 6387 6390 6404 6413 6428 6433 6435 6439 6441 6465 6472 6473 6474 6476 6489 6490 6494 6497 6504 6507 6512 6516 6520 6521 6524 6532 6534 6575 6577 6578 6590 6593 6601 6633 6639 6650 6659 6667 6670 6686 6689 6690 6696 6706 6719 6784 6797 6800 6851 6857 6883 6902 6925 6976 6985 6987 7010
HD	148390 148427 (Timir) 148531 149143 (Rosalíadecastro) 149382 150052 150381 150433 150493 152581 (Mahsati) 154088 156992 157172 160042 160346 164509 167162 170469 171028
Other	AS 239 BD-9 4395 CFHTWIR-Oph 98 CoRoT-6 CoRoT-25 CoRoT-26 DoAr 21 Elias 2-27 Gaia BH1 Gliese 673 GJ 1207 GJ 1214 GRS 1739-278 GX 1+4 GX 9+9 H 1705-250 Hen 3-1341 Great Annihilator IRAS 16293−2422 K2-32 LS IV-1 2 2MASS J16452211-1319516 MXB 1659-29 Oph-IRS 48 PG 1627-017 PSR B1929+10 TOI-677 Van Biesbroeck 8 VVV BD001 WISE 1800+0134 WISEP J180026.60+013453.1 Wolf 635 XTE J1739-285

Exoplanets	CFHTWIR-Oph 98 b 6b 25b 26b GJ 1214 b (Enaiposha) ν Ophiuchi b c

Star
clusters

NGC	6284 6287 6293 6304 6316 6325 6342 6355 6356 6366 6401 6426 6633
Other	IC 4665 Melotte 186 Messier 9 Messier 10 Messier 12 Messier 14 Messier 19 Messier 62 Messier 107 Palomar 6

Nebulae

NGC	6309 6572
Other	Dark Horse Double Helix Nebula Ophiuchus Superbubble Pipe Nebula Rho Ophiuchi cloud complex Serpens–Aquila Rift Snake Nebula