Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Equuleus |
Right ascension | 21h 10m 12.37231s [1] |
Declination | +10° 44′ 19.9495″ [1] |
Apparent magnitude (V) | 8.23±0.01 [2] |
Characteristics | |
Evolutionary stage | main sequence star |
Spectral type | A3 [3] |
B−V color index | 0.271±0.015 [4] |
Variable type | planetary transit [5] |
Astrometry | |
Radial velocity (Rv) | 14.0±0.2 [6] km/s |
Proper motion (μ) | RA: −5.691 mas/yr [1] Dec.: +5.066 mas/yr [1] |
Parallax (π) | 5.4889 ± 0.0237 mas [1] |
Distance | 594 ± 3 ly (182.2 ± 0.8 pc) |
Absolute magnitude (MV) | +1.81 [4] |
Details | |
Mass | 1.90+0.06 −0.07 [7] M☉ |
Radius | 2.1±0.2 [5] R☉ |
Luminosity | 12.0+0.9 −1.1 [7] L☉ |
Surface gravity (log g) | 4.09±0.14 [8] cgs |
Temperature | 7,490±150 [7] K |
Metallicity [Fe/H] | 0.00 [5] dex |
Rotational velocity (v sin i) | 109±4 [5] km/s |
Age | 800±200 [7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
HD 201585 is a star located in the equatorial constellation Equuleus. It has an apparent magnitude of 8.23, [2] making it readily visible in small telescopes but not to the naked eye. Gaia DR3 parallax measurements imply a distance of 594 light-years and it is currently receding with a heliocentric radial velocity of 14 km/s . [6] At its current distance, HD 201585's brightness is diminished by three-tenths of a magnitudes due to interstellar extinction [10] and it has an absolute magnitude of +1.81. [4] HD 201585 is the star's Henry Draper Catalogue designation. It is also designated as MASCARA-1 meaning that it is the first star observed by the MASCARA exoplanet search program.
HD 201585 has a stellar classification of A3, [3] indicating that it is an A-type star. However, later observations of the star's physical properties revealed a cooler class of A8. It has 1.9 times the mass of the Sun and 2.1 times the radius of the Sun. [5] It radiates 12 times the luminosity of the Sun from its photosphere at an effective temperature of 7,490 K , giving it the typical white hue of an A-type star. HD 201585 either has a solar metallicity or an iron abundance of [Fe/H] = +0.15, [5] depending on the source. Unfortunately, the latter value is poorly constrained. The star is estimated to be approximately 800 million years old and like most hot stars, it spins rapidly with a projected rotational velocity of 109 km/s .
HD 201585 b, also known as MASCARA-1b, was discovered around 2016 after astronomer G. J. J. Talens and colleagues observed planetary transit signals coming from HD 201585; its discovery was announced on July 13, 2017. [5] It is a hot Jupiter with 3.7 times the mass of Jupiter [5] and 1.60 times the radius of Jupiter. [7] MASCARA-1b has a measured equilibrium temperature of 2,594±2 K . [5] A 2022 study conducted on the planet found that it was unusually reflective for a hot Jupiter, having a geometric albedo of 0.171+0.066
−0.068. [7] Attempts to characterize its spectrum around the same year in a different study have failed due to MASCARA-1b's high surface gravity, resulting in a compact planetary atmosphere. [11]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
HD 201585/MASCARA-1b | 3.7±0.9 [5] MJ | 0.040352+0.000046 −0.000049 | 2.1487738±0.0000009 | 0.00034+0.00034 −0.00023 | 88.45±0.17° | 1.597+0.018 −0.019 RJ |
21 Aquilae is a solitary variable star in the equatorial constellation of Aquila. It has the variable star designation V1288 Aql; 21 Aquilae is its Flamsteed designation. This object is visible to the naked eye as a dim, blue-white hued star with a baseline apparent visual magnitude of about 5.1. The star is located at a distance of around 680 light-years from Earth, give or take a 20 light-year margin of error. It is moving closer to the Earth with a heliocentric radial velocity of –5 km/s.
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HD 183144 is suspected variable star in the equatorial constellation of Aquila. It is a hot giant star about 1,130 light years away.
HD 33463 is a suspected variable star in the northern constellation of Auriga, about 1,050 light years away. It is a red giant star with a stellar classification of M2III, and has expanded away from the main sequence after exhausting its core hydrogen. It has reached 133 times the size of the Sun and, at an effective temperature of 3,753 K it shines at a bolometric luminosity of 2,114 L☉.
HD 135438 is a K-type giant star in the northern constellation of Boötes. With an apparent magnitude of 6.0, it lies about 650 light years away.
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HD 101570 is a single star in the southern constellation of Centaurus. It has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.93. The star is located at a distance of approximately 1,080 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +18 km/s. It has an absolute magnitude of −2.24.
HD 63399 is an orange hued star located in the southern constellation Puppis, the poop deck. It has an apparent magnitude of 6.45, placing it near the limit for naked eye visibility. Based on parallax measurements from Gaia DR3, the object is estimated to be 445 light years distant. It appears to be receding with a spectroscopic radial velocity of 28.5 km/s. At its current distance, HD 63399 is diminished by 0.29 magnitudes due to interstellar dust.
S Boötis is a Mira variable in the constellation Boötes. It ranges between magnitudes 7.8 and 13.8 over a period of approximately 270 days. It is too faint to be seen with the naked eye, however when it is near maximum brightness it can be seen with binoculars.
HD 39901 is an orange hued star located in the constellation Columba. It is also called HR 2069, which is the star's Bright Star Catalog designation. Eggen (1989) lists it as a member of the old disk population.
HD 49268 is a solitary star in the southern circumpolar constellation Volans. It has an apparent magnitude of +6.49, placing it near the limit of naked eye visibility. Parallax measurements place the object at a distance of 456 light years; it is receding with a heliocentric radial velocity of 20.6 km/s.
HD 66920, also known as HR 3171, is a solitary, white hued star located in the southern circumpolar constellation Volans, the flying fish. It has an apparent magnitude of 6.33, placing it near the limit for naked eye visibility. Based on parallax measurements from the Gaia spacecraft, the star is estimated to be 428 light years distant. It appears to be receding from the Solar System, having a heliocentric radial velocity of 23.8 km/s. Pauzen et al. (2001) listed it as a λ Boötis star, but is now considered a non member.
HD 76236, also designated as HR 3543 or rarely 11 G. Chamaeleontis, is a solitary star located in the southern circumpolar constellation Chamaeleon. It is faintly visible to the naked eye as an orange-hued star with an apparent magnitude of 5.77. Based on parallax measurements from the Gaia satellite, the object is estimated to be 612 light years away. Currently, it is receding with a heliocentric radial velocity of 7 km/s. At its current distance, HD 76236's brightness is diminished by 0.39 magnitudes due to interstellar dust. It has an absolute magnitude of −0.13.
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HD 37289, also known as HR 1916, is a solitary, orange hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.61, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from the Gaia spacecraft, the object is estimated to be 308 light years distant. It appears to be approaching the Sun, having a heliocentric radial velocity of −20.7 km/s.
WD 0810-353 is a white dwarf currently located 36 light-years from the Solar System. This stellar remnant may approach the Solar System 29,000 years from now at a distance of around 0.15 parsecs, 0.49 light-years or 31,000 AU from the Sun, crossing well within the proposed boundaries of the Oort cloud. Such close proximity will almost certainly make its flyby the closest in the future, until the flyby of Gliese 710 occurs around 1.14 million years after the dwarf's flyby.
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