HD 73256 is a variable star in the southern constellation of Pyxis. It has the variable star designation CS Pyxidis. With a baseline apparent visual magnitude of 8.08, [2] it requires binoculars or a small telescope to view. The star is located at a distance of 120 light years from the Sun based on parallax, [1] and is drifting further away with a radial velocity of +30 km/s. [2]
The stellar classification of this star is G8IV-VFe+0.5, which suggests a slightly evolved G-type main-sequence star with a mild overabundance of iron in the spectrum. It is a BY Draconis variable with a period of 13.97 days, showing a variation of 0.03 in magnitude due to chromospheric activity. [4] The star appears overluminous for its class, which may be the result of a high metallicity. [6] The star has roughly the same mass and a slightly smaller radius as the Sun, but is radiating 74% of the Sun's luminosity. [5] It is around 2–3 billion years old and is spinning with a projected rotational velocity of 3.2 km/s. [6]
In 2003, S. Udry and colleagues reported the discovery of a planet in orbit around HD 73256 using data from the CORALIE spectrograph. This object is a hot Jupiter with at least 1.87 times the mass of Jupiter in an orbit with a period of 2.55 days. [6] Assuming the planet is perfectly grey with no greenhouse or tidal effects, and a Bond albedo of 0.1, the temperature would be about 1300 K. This is close to 51 Pegasi b; between the predicted temperatures of HD 189733 b and HD 209458 b (1180-1392K), before they were measured. It is a candidate for "near-infrared characterisation with the VLTI Spectro-Imager". [8]
In 2018, K. Ment and colleagues reported an attempt to confirm the existence of this planet using Keck/HIRES data, but were unable to do so despite a likelihood of success. Thus the existence of this object is disputed. [9]
In 2023, a different substellar companion on a wide orbit, likely a brown dwarf, was discovered using both radial velocity and astrometry. This study did also detect HD 73256 b, but did not update its parameters or address the dispute. [10]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b(disputed) | >1.87 ± 0.49 MJ | 0.037 | 2.54858 ± 0.00016 | 0.029 ± 0.02 | — | — |
c | 16±1 MJ | 3.8±0.1 | 2690+60 −102 | 0.16±0.07 | 29+5 −3 or 152+8 −7 ° | — |
HD 169830 is a star in the southern constellation of Sagittarius. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.90. The star is located at a distance of 120 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −17.3 km/s, and is predicted to come as close as 20.7 ly (6.4 pc) in 2.08 million years. HD 169830 is known to be orbited by two large Jupiter-like exoplanets.
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.
HR 7703 is a binary star system in the constellation of Sagittarius. The brighter component has an apparent visual magnitude of 5.31, which means it is visible from suburban skies at night. The two stars are separated by an angle of 7.10″, which corresponds to an estimated semimajor axis of 56.30 AU for their orbit.
Gliese 1 is a red dwarf in the constellation Sculptor, which is found in the southern celestial hemisphere. It is one of the closest stars to the Sun, at a distance of 14.2 light years. Because of its proximity to the Earth it is a frequent object of study and much is known about its physical properties and composition. However, with an apparent magnitude of about 8.6 it is too faint to be seen with the naked eye.
HD 196885 is a binary star system in the northern constellation of Delphinus. It comprise a pair of stars HD 196885 A and HD 196885 B on a 69-years eccentric orbit.
HD 1237 is a binary star system approximately 57 light-years away in the constellation of Hydrus.
HD 102195 is an orange-hued star in the zodiac constellation of Virgo with a confirmed exoplanet companion. With an apparent visual magnitude of 8.07, the star is too faint to be seen with the naked eye. The distance to HD 102195 can be estimated from its annual parallax shift of 34.06 mas, yielding 95.8 light years. It is moving further away from the Earth with a heliocentric radial velocity of 1.85 km/s. This is a high proper motion star and a possible member of the η Cha stellar kinematic group.
HD 80606 and HD 80607 are two stars comprising a binary star system. They are approximately 217 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. The binary system is listed as Struve 1341 in the Struve Catalogue of Double Stars; however, this designation is not in wide use and the system is usually referred to by the HD designations of its constituent stars. An extrasolar planet has been confirmed to orbit HD 80606 in a highly elliptical orbit.
HD 132406 is a star in the northern constellation of Boötes. With an apparent visual magnitude of 8.45, it is invisible to the naked eye. The distance to this star is 230 light-years based on parallax, but it is drifting closer with a radial velocity of −37.8 km/s. The star has an absolute magnitude of 4.30. It has one confirmed exoplanet companion.
HD 171028 is a star with an exoplanet companion in the equatorial constellation of Ophiuchus. With an apparent visual magnitude of 8.3, 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.
HD 33564 is a single star with an exoplanetary companion in the northern constellation of Camelopardalis. It has an apparent visual magnitude of 5.08, which means it is a 5th magnitude star that is faintly visible to the naked eye. The system is located at a distance of 68 light years from the Sun based on parallax, and it is drifting closer with a radial velocity of −11 km/s. It is a candidate member of the Ursa Major Moving Group.
HD 190647 is a yellow-hued star with an exoplanetary companion, located in the southern constellation of Sagittarius. It has an apparent visual magnitude of 7.78, making this an 8th magnitude star that is much too faint to be readily visible to the naked eye. The star is located at a distance of 178 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −40 km/s. It is also called HIP 99115.
HD 4113 is a dual star system in the southern constellation of Sculptor. It is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.88. The distance to this star, as estimated by parallax measurements, is 137 light years. It is receding away from the Sun with a radial velocity of +5 km/s.
HD 117207 is a star in the southern constellation Centaurus. With an apparent visual magnitude of 7.24, it is too dim to be visible to the naked eye but can be seen with a small telescope. Based upon parallax measurements, it is located at a distance of 105.4 light-years from the Sun. The star is drifting closer with a radial velocity of −17.4 km/s. It has an absolute magnitude of 4.67.
HD 179949 b, formally named Mastika, is an extrasolar planet discovered by the Anglo-Australian Planet Search at the Anglo-Australian Observatory, which orbits the star HD 179949. The planet is a so-called "hot Jupiter", a Jupiter-mass planet orbiting very close to its parent star. In this case, orbital distance is almost one-tenth that of Mercury from the Sun. One orbital revolution lasts only about 3 days.
HD 45652 is a star with an exoplanetary companion in the equatorial constellation of Monoceros. It was officially named Lusitânia on 17 December 2019, after the IAU100 press conference in Paris by the IAU. This star has an apparent visual magnitude of 8.10, making it an 8th magnitude star that is too dim to be visible to the naked eye. The system is located at a distance of 114 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −5 km/s. It shows a high proper motion, traversing the celestial sphere at an angular rate of 0.188 arcsec yr−1.
HIP 70849 is a star with two non-stellar companions in the southern constellation Lupus. It is a 10th magnitude star, making it too faint to be visible to the naked eye. The system is located at a distance of 78.7 light-years from the Sun based on parallax measurements.
HD 175167 is a star with an exoplanet companion in the southern constellation of Pavo. It is too faint to be visible with the naked eye at an apparent visual magnitude of 8.01. The system is located at a distance of 232 light-years from the Sun based on parallax measurements, and it is drifting further away with a radial velocity of 5 km/s. It shows a high proper motion, traversing the celestial sphere at an angular rate of 0.190 arcsec yr−1.
HD 15082 is a star located roughly 399 light years away in the northern constellation of Andromeda. The star is a Delta Scuti variable and a planetary transit variable. A hot Jupiter type extrasolar planet, named WASP-33b or HD 15082b, orbits this star with an orbital period of 1.22 days. It is the first Delta Scuti variable known to host a planet.
Sigma Ophiuchi, Latinized from σ Ophiuchi, is a single, orange-hued star in the equatorial constellation Ophiuchus. Its apparent visual magnitude is 4.31, which is bright enough to be faintly visible to the naked eye. The annual parallax shift of 3.62 mas as seen from Earth provides a distance estimate of roughly 900 light years. It is moving closer to the Sun with a radial velocity of −28 km/s.