Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Eridanus |
Right ascension | 03h 55m 16.13133s [2] |
Declination | −12° 05′ 56.7277″ [2] |
Apparent magnitude (V) | 5.97 - 6.00 [3] |
Characteristics | |
Spectral type | A9Vp SrEuCr [4] |
Variable type | roAp [5] |
Astrometry | |
Proper motion (μ) | RA: −91.357±0.036 [2] mas/yr Dec.: −28.376±0.036 [2] mas/yr |
Parallax (π) | 20.7432 ± 0.0413 mas [2] |
Distance | 157.2 ± 0.3 ly (48.21 ± 0.10 pc) |
Absolute magnitude (MV) | 2.32 [6] |
Details | |
Mass | 1.54±0.13 [7] M☉ |
Radius | 1.75±0.05 [7] R☉ |
Luminosity | 7.6±1.2 [7] L☉ |
Surface gravity (log g) | 4.30 [8] cgs |
Temperature | 7,235±280 [7] K |
Metallicity [Fe/H] | −0.36 [8] dex |
Rotation | 12.46 d [7] |
Rotational velocity (v sin i) | 7.0 [8] km/s |
Age | 780+760 −470 [7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
HR 1217 is a variable star in the constellation Eridanus. It has the variable star designation DO Eridani, but this seldom appears in the astronomical literature; it is usually called either HR 1217 or HD 24712. At its brightest, HR 1217 has an apparent magnitude of 5.97, making it very faintly visible to the naked eye for an observer with excellent dark-sky conditions. [5]
HR 1217 is one of the best-studied rapidly oscillating Ap (roAp) stars. [1] Inspired by the 1978 discovery of the rapid (12 minute period) brightness variability of Przybylski's Star (an Ap star), in 1980 D. W. Kurtz observed the Ap star HR 1217, and found clear 6.15 minute oscillations, the amplitude of which slowly changed over the course of several days. [10] The next year, high-speed photometric observations of the star revealed six nearly equally spaced pulsation periods ranging from 6.126 minutes (strongest) to 5.966 minutes (weakest). [11] In 1989 it was found that the amplitudes of these pulsations are modulated over a period equal to the star's rotation period. [12] By 2019, ten pulsation frequencies had been found in the TESS data. [13]
HR 1217 is a chemically peculiar star, with particular over-abundances of copper, europium, and chromium in its spectrum. [4] At the same time, lines of other metals such as iron are less strong than expected for an A9 star, which is typical of an Ap star. In 2009, Shulyak et al. computed a model atmosphere for the star which showed how the elemental abundances varied as a function of atmospheric height. [14] In 2015, doppler imaging was used to produce maps of both the star's magnetic field and the distribution of several chemical elements across the star's surface. It was the first roAp star to be mapped in this way. [15]
Gamma Doradus variables are variable stars which display variations in luminosity due to non-radial pulsations of their surface. The stars are typically young, early F or late A type main sequence stars, and typical brightness fluctuations are 0.1 magnitudes with periods on the order of one day. This class of variable stars is relatively new, having been first characterized in the second half of the 1990s, and details on the underlying physical cause of the variations remains under investigation.
Przybylski's Star, or HD 101065, is a rapidly oscillating Ap star at roughly 356 light-years from the Sun in the southern constellation of Centaurus. It has a unique spectrum showing over-abundances of most rare-earth elements, including some short-lived radioactive isotopes, but under-abundances of more common elements such as iron.
V1291 Aquilae is a single star in the equatorial constellation of Aquila. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude that fluctuates around 5.65. Based on parallax measurements, it is located at a distance of approximately 278 light years from the Sun. The star it is drifting closer with a radial velocity of −22 km/s.
BX Boötis is a star in the northern constellation of Boötes. It is a dim star near the lower limit of visibility to the naked eye, having a nominal apparent visual magnitude of 6.35. Based upon an annual parallax shift of 10.81 mas, it is located 302 light years away. At that distance, the visual magnitude of the star is diminished by an extinction of 0.13 due to interstellar dust. It is moving closer with a heliocentric radial velocity of −11 km/s.
BN Camelopardalis is a suspected astrometric binary in the northern circumpolar constellation of Camelopardalis. It appears as a variable star that is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude that fluctuates around 5.49. The system is located at a distance of around 310 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +9 km/s.
Rapidly oscillating Ap stars (roAp stars) are a subtype of the Ap star class that exhibit short-timescale rapid photometric or radial velocity variations. The known periods range between 5 and 23 minutes. They lie in the δ Scuti instability strip on the main sequence.
Gamma Equulei, Latinized from γ Equulei, is a double star in the northern constellation of Equuleus. It is located at a distance of around 118 light-years from Earth and is visible to the naked eye with a slightly variable apparent visual magnitude of around 4.7. The star is drifting closer to the Sun with a radial velocity of −16.5 km/s.
HD 105382 is a star in the constellation Centaurus. Its apparent magnitude is 4.47. From parallax measurements, it is located 130 parsecs from the Sun.
S Apodis, also known as HD 133444 is a variable star located in the southern circumpolar constellation Apus. It has an apparent magnitude ranging from 9.6 to 17, which is below the limit for naked eye visibility. The object is located relatively far at a distance of approximately 15,000 light years based on Gaia DR3 parallax measurements, but it is drifting closer with a heliocentric radial velocity of −75 km/s.
HD 137509 is a star in the southern constellation of Apus, positioned less than a degree from the northern constellation boundary with Triangulum Australe. It has the variable star designation of NN Apodis, or NN Aps for short, and ranges in brightness from an apparent visual magnitude of 6.86 down to 6.93 with a period of 4.4916 days. The star is located at a distance of approximately 647 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +0.50 km/s.
Xi Phoenicis, Latinized from ξ Phoenicis, is a visual binary star system in the southern constellation of Phoenix. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.70. Based upon an annual parallax shift of 14.61 mas as measured from Earth, it is located around 223 light years from the Sun. The system is moving away from the Sun with a radial velocity of about +10 km/s.
Rho Phoenicis is a variable star in the constellation of Phoenix. From parallax measurements by the Gaia spacecraft, it is located at a distance of 245 light-years from Earth.
HD 74423 is a heartbeat binary star and one component pulsates on only one hemisphere. This is caused by tidal interaction with its partner. The star is located in the Volans constellation.
HR 3831, also known as HD 83368, is a binary star system in the southern constellation of Vela at a distance of 233 light years. This object is barely visible to the naked eye as a dim, blue star with an apparent visual magnitude of 6.232. It is approaching the Earth with a heliocentric radial velocity of 4.0±0.3 km/s.
17 Comae Berenices is a multiple star system in the northern constellation of Coma Berenices. The brighter component, 17 Com A, is a naked eye star with an apparent visual magnitude of 5.2. It has a faint companion of magnitude 6.6, 17 Com B, positioned at an angular separation of 146.4″ along a position angle of 251°, as of 2018. They are located at a distance of approximately 240 light years from the Sun based on parallax measurements.
HR 7355 is a star in the southern constellation of Sagittarius. It is faintly visible to the naked eye with an apparent visual magnitude of 6.03. The star is located at a distance of approximately 760 light years based on parallax measurements. The radial velocity of the star is poorly constrained, but it appears to be receding at the rate of +4 km/s.
HD 125248 is a binary star system in the equatorial constellation of Virgo. It has the variable star designation CS Virginis, while HD 125248 is the designation from the Henry Draper Catalogue. This system is dimly visible to the naked eye as a point of light with an apparent visual magnitude that ranges from 5.84 down to 5.95. It is located at a distance of approximately 280 light years from the Sun based on parallax measurements, but is drifting closer with a heliocentric radial velocity of −8 km/s.
HD 133880, also known as HR 5624 and HR Lupi, is a Bp star about 340 light years from the Earth, in the constellation Lupus. It is a 5th magnitude star, and will be faintly visible to the naked eye of an observer far from city lights. It is an SX Arietis variable star, varying from magnitude 5.76 to 5.81 over a period of 21.0594 hours. HD 133880 is a member of the Upper Centaurus–Lupus association. It is a young star, estimated to have completed only 5±2 percent of its projected main sequence lifetime. It is one of the few stars known to produce coherent pulsed radio radiation via electron cyclotron maser emission.
HR 1170, also known as HD 23728 and V376 Persei, is a star about 220 light years from the Earth, in the constellation Perseus. It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights. It is a variable star, whose brightness varies slightly from magnitude 5.77 to 5.91.
QQ Telescopii, also known as HD 185139 or simply QQ Tel, is a solitary variable star located in the southern constellation Telescopium. It has an apparent magnitude of 6.25, placing it near the limit for naked eye visibility, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 333 light years and it is currently receding with a heliocentric radial velocity of 7.8 km/s. At its current distance, QQ Telescopii's brightness is diminished by two tenths of a magnitude due to interstellar dust and it has an absolute magnitude of +1.01.