HD 170657

Last updated
HD 170657
Observation data
Epoch J2000       Equinox J2000
Constellation Sagittarius
Right ascension 18h 31m 18.96122s [1]
Declination –18° 54′ 31.7326″ [1]
Apparent magnitude  (V)6.81 [2]
Characteristics
Evolutionary stage Main sequence
Spectral type K2V [3]
U−B color index +0.56 [4]
B−V color index +0.861±0.007 [2]
Variable type Suspected [5]
Astrometry
Radial velocity (Rv)−43.16±0.14 [6]  km/s
Proper motion (μ)RA: –138.402 [1]   mas/yr
Dec.: –195.274 [1]   mas/yr
Parallax (π)75.9773 ± 0.0458 [1]   mas
Distance 42.93 ± 0.03  ly
(13.162 ± 0.008  pc)
Absolute magnitude  (MV)6.20 [2]
Details
Mass 0.79±0.11 [7]   M☉
Radius 0.75+0.01
−0.04 [1]   R☉
Luminosity 0.336±0.001 [1]   L☉
Surface gravity (log g)4.59 [8]   cgs
Temperature 5,133±37 [8]   K
Metallicity [Fe/H]–0.15 [7]   dex
Rotational velocity (v sin i)4.2 [8]  km/s
Age 7.95 [8]   Gyr
Other designations
NSV  10944, GJ  716, HD  170657, HIP  90790, SAO  161557, WDS J18313-1855A, LTT  7358 [9]
Database references
SIMBAD data
ARICNS data

HD 170657 is a star in the southern constellation Sagittarius. It is a suspected variable star that has been measured ranging in apparent visual magnitude from 6.82 down to 6.88, [5] which is dim enough to be a challenge to view with the naked eye even under ideal conditions. The star is located at a distance of 43  light years from the Sun based on parallax. It is drifting closer with a radial velocity of −43 km/s, and is predicted to come as close as 14.0 light-years in around 266,200 years. [6] The space velocity components of this star are (U, V, W) = (–41, –26, +6) km/s. [10]

This is a K-type main-sequence star with a stellar classification of K2V, [3] which indicates that, much like the Sun, it is generating energy at its core using hydrogen fusion. The star has 79% [7] of the mass of the Sun and 75% [1] of the Sun's radius. It is nearly eight [8]  billion years old and is spinning with a projected rotational velocity of 4.2  [8] The star is radiating 33.6% [1] of the luminosity of the Sun from its photosphere at an effective temperature of 5,133 K. [8] When observed with the Spitzer Space Telescope, this star did not display an excess emission of infrared radiation, which may otherwise indicate the presence of an orbiting debris disk. [11]

Related Research Articles

HD 210277 is a single star in the equatorial constellation of Aquarius. It has an apparent visual magnitude of 6.54, which makes it a challenge to view with the naked eye, but it is easily visible in binoculars. The star is located at a distance of 69.5 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −20.9 km/s.

Kappa<sup>1</sup> Sagittarii Star in the constellation Sagittarius

Kappa1 Sagittarii (κ1 Sagittarii) is a solitary, white-hued star in the zodiac constellation of Sagittarius. It has an apparent visual magnitude of +5.58, which is bright enough to be faintly visible to the naked eye. According to the Bortle scale, it can be viewed from dark suburban skies. Based upon an annual parallax shift of 15.12 mas as seen from Earth, this star is located around 223 light years from the Sun. It is advancing in the general direction of the Sun with a radial velocity of −11.6 km/s.

Lambda1 Tucanae is the Bayer designation for one member of a pair of stars sharing a common proper motion through space, which lie within the southern constellation of Tucana. As of 2013, the pair had an angular separation of 20.0 arc seconds along a position angle of 82°. Together, they are barely visible to the naked eye with a combined apparent visual magnitude of 6.21. Based upon an annual parallax shift for both stars of approximately 16.5 mas as seen from Earth, this system is located roughly 198 light years from the Sun.

Delta Antliae

Delta Antliae is the Bayer designation for a binary star system in the southern constellation of Antlia. The combined apparent visual magnitude of the system is +5.57, allowing it to be viewed from the suburbs with the naked eye. Judging by the parallax shift of this system, it is located at a distance of 450 ± 10 light-years from Earth. The system is reduced in magnitude by 0.03 due to extinction caused by intervening gas and dust.

39 Aquarii is a star in the zodiac constellation of Aquarius. 39 Aquarii is its Flamsteed designation. It is a faint naked eye star with an apparent visual magnitude of 6.03. Based upon an annual parallax shift of 23.78 measured with a 3% margin of error, this star is at a distance of around 137 light-years from Earth. It is a double star with a magnitude 9.3 companion at an angular separation of 0.6 arcseconds along a position angle of 257°.

70 Aquarii is a variable star located 425 light years away from the Sun in the equatorial constellation of Aquarius. It has the variable star designation FM Aquarii; 70 Aquarii is the Flamsteed designation. It is near the lower limit of visibility to the naked eye, appearing as a dim, yellow-white hued star with a baseline apparent visual magnitude of 6.19. This star is moving closer to the Earth with a heliocentric radial velocity of –5.8 km/s.

11 Aquarii is a sun-like star in the zodiac constellation of Aquarius, located 88.5 light years away from the Sun. 11 Aquarii is the Flamsteed designation. It is difficult to see with the naked eye, appearing as a dim, yellow-hued star with an apparent visual magnitude of 6.22. This body is moving closer to the Earth with a heliocentric radial velocity of −17.8 km/s, and is expected to come as close as 65.1 ly in 700,000 years.

8 Aquilae is a star in the equatorial constellation of Aquila, located 266 light years away from the Sun. 8 Aquilae is the Flamsteed designation. It can be viewed with the naked eye in good seeing conditions, appearing as a dim, yellow-white hued star with an apparent visual magnitude of 6.08. The star is moving further from the Earth with a heliocentric radial velocity of +12 km/s.

3 Centauri is a triple star system in the southern constellation of Centaurus, located approximately 300 light years from the Sun. It is visible to the naked eye as a faint, blue-white hued star with a combined apparent visual magnitude of 4.32. As of 2017, the two visible components had an angular separation of 7.851″ along a position angle of 106°. The system has the Bayer designation k Centauri; 3 Centauri is the Flamsteed designation. It is a suspected eclipsing binary with a variable star designation V983 Centauri.

HD 50281 is a star in the equatorial constellation of Monoceros. It is orange in hue with an apparent visual magnitude of 6.58, which lies at or below the typical limit of visibility to the naked eye. The star is located at a distance of 28.5 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −7.2 km/s.

HR 5256 is a star located thirty-three light-years away from the Sun in the northern circumpolar constellation of Ursa Major. It has an orange hue and is a challenge to view with the naked eye, having an apparent visual magnitude of 6.52 The distance to this star is very nearly 10 parsecs, so the absolute magnitude of 6.51 is nearly the same as the star's apparent magnitude. HR 5256 is drifting nearer to the Sun with a radial velocity of −26.4 km/s, and will make its closest approach to the Sun in about 333,000±16,000 years, when it will be at a distance of 12.72 ± 0.65 light-years.

HD 179791 is suspected variable star in the equatorial constellation of Aquila. It is a challenge to see with the naked eye even under good viewing conditions, having an apparent visual magnitude of 6.48. The distance to HD 179791 can be estimated from its annual parallax shift of 5.3 mas, which yields a value of 616 light years. It is moving further from the Earth with a heliocentric radial velocity of +16 km/s. Astrometric measurements of the star show changes in motion that may indicate it is a member of a close binary system.

HD 7924 Star in the constellation Cassiopeia

HD 7924 is a single star located 55.5 light years away from the Sun in the northern constellation of Cassiopeia, near the northern constellation border with Cepheus. It has an orange hue and is only visible by means of binoculars or a telescope due to a low apparent visual magnitude of 7.167. The star is drifting closer to the Sun with a radial velocity of –22.7 km/s, and is expected to approach to within 9.3 light-years in around 711,700 years.

HD 145377 is a star in the southern constellation Scorpius. It has an apparent visual magnitude of 8.10 and can be viewed with a small telescope. The star is located at a distance of 175 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +11.6. The absolute magnitude of this star is 4.31, indicating it would be visible to the naked eye if it were at a distance of 10 parsecs.

Zeta<sup>1</sup> Antliae Binary star system in the constellation Antlia.

Zeta1 Antliae is the Bayer designation for a binary star system in the southern constellation of Antlia. Based upon parallax measurements, the pair are located at a distance of roughly 350 light-years from Earth. They have apparent magnitudes of +6.20 and +7.01 and are separated by 8.042 arcseconds. The apparent magnitude of the combined system is +5.76, which is bright enough to be seen with the naked eye in suitably dark skies.

5 Vulpeculae

5 Vulpeculae is a single, white-hued star in the northern constellation of Vulpecula. It is situated amidst a random concentration of bright stars designated Collinder 399, or Brocchi's Cluster. This is a faint star that is just visible to the naked eye with an apparent visual magnitude of 5.60. Based upon an annual parallax shift of 13.8921±0.0900 mas, it is located around 235 light years from the Sun. It is moving closer with a heliocentric radial velocity of −21 km/s, and will make its closest approach in 2.5 million years at a separation of around 120 ly (36.89 pc).

HD 154577 is a solar-type star in the southern constellation of Ara. It is a high proper motion star and, based upon an annual parallax shift of 73.41 mas, is located about 44 light years from the Sun. The star is too faint to be readily visible to the naked eye, having an apparent visual magnitude of 7.4. It is moving away from the Sun with a radial velocity of +9 km/s.

θ Normae, Latinised as Theta Normae, is a binary star system in the constellation Norma. It has an apparent visual magnitude of 5.13 and is visible to the naked eye as a faint, blue-white hued point of light. Based upon an annual parallax shift of 9.27 mas as seen from Earth, this system is located about 352 light years from the Sun. At that distance, the visual magnitude of these stars is diminished by an extinction of 0.45 due to interstellar dust.

HD 76653 is a single star in the southern constellation Vela. It is faintly visible to the naked eye with an apparent visual magnitude of +5.71. Based upon an annual parallax shift of 41.22 mas as seen from Earth, it is located 79 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −6 km/s. It is a probable co-moving companion of the nearby Delta Velorum; the two have an estimated physical separation of 2.2 ly (0.6605 pc) with similar proper motions. Both are likely members of the Ursa Major association.

89 Leonis is a single star in the equatorial constellation of Leo, the lion. It has a yellow-white hue and is faintly visible to the naked eye with an apparent visual magnitude of 5.70. Based upon parallax measurements, it is located at a distance of 88 light years from the Sun. The star has a high proper motion and is moving further away with a radial velocity of +4.8 km/s. It is a candidate member of the TW Hydra stellar kinematic group.

References

  1. 1 2 3 4 5 6 7 8 9 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.
  2. 1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID   119257644.
  3. 1 2 Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv: astro-ph/0603770 . Bibcode:2006AJ....132..161G. doi:10.1086/504637.
  4. ↑ Corben, P. M.; Carter, B. S.; Banfield, R. M.; Harvey, G. M. (1972). "UBV Photometry of 500 Southern Stars [erratum: 1973MNSSA..32...48C]". Monthly Notes of the Astronomical Society of Southern Africa. 31: 7. Bibcode:1972MNSSA..31....7C.
  5. 1 2 Kukarkin, B. V.; et al. (1981). Nachrichtenblatt der Vereinigung der Sternfreunde e.V. (Catalogue of suspected variable stars). Moscow: Academy of Sciences USSR Shternberg. Bibcode:1981NVS...C......0K.
  6. 1 2 Bailer-Jones, C.A.L.; et al. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics. 616: A37. arXiv: 1805.07581 . Bibcode:2018A&A...616A..37B. doi:10.1051/0004-6361/201833456.
  7. 1 2 3 Valenti, Jeff A.; Fischer, Debra A. (July 2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi: 10.1086/430500 .
  8. 1 2 3 4 5 6 7 Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 19. arXiv: 1611.02897 . Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID   119511744. 21.
  9. ↑ "HD 170657". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-11-09.
  10. ↑ Gliese, W. (1969). Catalogue of Nearby Stars. Heidelberg: Veröffentlichungen des Astronomischen Rechen-Instituts. Bibcode:1969VeARI..22....1G.
  11. ↑ Lawler, S. M.; et al. (November 2009). "Explorations Beyond the Snow Line: Spitzer/IRS Spectra of Debris Disks Around Solar-type Stars". The Astrophysical Journal. 705 (1): 89–111. arXiv: 0909.0058 . Bibcode:2009ApJ...705...89L. doi:10.1088/0004-637X/705/1/89.
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