Observation data Epoch J2000 [1] Equinox J2000 [1] | |
---|---|
Constellation | Cepheus |
Right ascension | 20h 43m 21.60554s |
Declination | +63° 12′ 32.8418″ |
Apparent magnitude (V) | 7.669 [2] |
Characteristics | |
Spectral type | B5 [2] |
B−V color index | −0.01 [1] |
J−H color index | −0.109 [1] |
J−K color index | −0.107 [1] |
Astrometry | |
Radial velocity (Rv) | −3.80±3.5 km/s |
Proper motion (μ) | RA: −13.478 [3] mas/yr Dec.: -3.025 [3] mas/yr |
Parallax (π) | 1.0802 ± 0.0214 mas [3] |
Distance | 3,020 ± 60 ly (930 ± 20 pc) |
Details [2] | |
Mass | 6.320±0.316 M☉ |
Radius | 9.218±0.461 R☉ |
Other designations | |
Database references | |
SIMBAD | HD 197911 |
HD 197911 (HIP 102274) is a bluish-white hued star in the deep northern constellation of Cepheus, close to the border with Draco and Cygnus. With an apparent magnitude of 7.669, it is too faint to be seen by the naked eye under most conditions, but readily visible using binoculars. [4] The star is located some 3,020 light-years (930 parsecs) distant according to Gaia EDR3 parallax measurements, but is moving closer to the Solar System at a heliocentric radial velocity of −3.8±3.5 km/s .
The star appears close to the reflection nebula and H II region [5] Sh2-130, alongside the A0-type star HD 197809 and G5-type star SAO 18999, [6] though the latter two stars are located much closer to Earth at 469 ly (144 pc) [7] and 198 ly (61 pc), [8] respectively. The cluster itself is situated at a distance of 600 pc (2,000 ly). [6]
HD 197911 is a massive B-type star with the spectral type B5, a mass 6.3 times that of the Sun and 9.2 times the radius. It is a runaway star traversing space at a peculiar velocity of 56.69 km/s. The star is thought to have once been part of a binary system, from which it was ejected as its companion ended its life in a supernova. [9]
Initially, the star was thought to have originated in an OB association called the Cepheus OB2 association, which it left 2–3 million years ago, when the association was 3–4 million years old. This aligned with the age of the Cepheus bubble, an annular structure of infrared emission, providing compelling evidence for the binary-supernova scenario, that is, that it was blasted out of a binary system by a companion going supernova. [10]
However, with updated astrometric data, it is now considered more likely that it formed in either Alessi-Teutsch 5 or NGC 7160, two star clusters that are each 12.5 and 9.0 million years old. Both origins are consistent with the initially proposed scenario. [9]
36 Ophiuchi is a triple star system 19.5 light-years from Earth. It is in the constellation Ophiuchus.
Winnecke 4 is an optical double star consisting of two unrelated stars in a northerly zone of the sky, Ursa Major.
HD 225218 is a quadruple star system in the northern constellation of Andromeda. The primary component, HD 225218 A, is a giant star with a stellar classification of B9III, an apparent magnitude of 6.16, and is a candidate Lambda Boötis star. It has a fainter, magnitude 9.65 companion, HD 225218 B, at an angular separation of 5.2″ along a position angle of 171°. The primary itself has been identified as a binary star system through interferometry, with the two components separated by 0.165″. The pair, HD 225218 Aa and Ab, orbit each other with a period of about 70 years and an eccentricity of 0.515. Component B is likewise a spectroscopic binary.
HD 6114 is a visual binary star system in the northern constellation of Andromeda. With a combined apparent magnitude of 6.46, the star can only be seen with the naked eye by keen-eyed observers even on the best of nights. Based upon an annual parallax shift of 10.4 mas as seen from Earth's orbit, the system is located approximately 108 parsecs (350 ly) distant.
4 Camelopardalis is a probable multiple star in the northern constellation of Camelopardalis, located 177 light years away from the Sun, based upon parallax. With a combined apparent visual magnitude of 5.29, it is visible to the naked eye as a faint, white-hued star. The pair have a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.158″ per year. The system's proper motion makes it a candidate for membership in the IC 2391 supercluster. They are moving away from the Earth with a heliocentric radial velocity of 22.5 km/s.
1 Camelopardalis is a double star system in the constellation Camelopardalis. Its combined apparent magnitude is 5.56 and it is approximately 800 parsecs (2,600 ly) away.
2 Equulei is a double star system in the constellation of Equuleus.
ADS 9731 is a star system that consists of six stars, located in the constellation of Corona Borealis. Four of the stars are visually separate in the sky, forming a visual star system, which was resolved using adaptive optics in 1995. Two of these stars were themselves found to be spectroscopic binaries in 1998, resulting in a total of six known stars in the system. It is one of very few multiple star systems known to have at least six members.
2MASS J18450079–1409036 and 2MASS J18450097–1409053 is a system of two red dwarf stars both of which have spectral types of M5, with projected separation of 3.2 seconds of arc. The system is located in the constellation Scutum. The Gaia parallaxes place the system at 18.2 parsecs from Earth. Kinematically, it belongs to young Argus association.
1 Delphini is the Flamsteed designation for a close binary star in the equatorial constellation Delphinus. With a combined apparent magnitude of 6.08, it is barely visible to the naked eye, even under ideal conditions. Parallax measurements put the components at a distance 703 and 780 light years respectively. However, its approaching the Solar System with a radial velocity of 15 km/s.
HD 197037 is a binary star system. Its primary or visible star, HD 197037 A, is a F-type main-sequence star. Its surface temperature is 6150±34 K. HD 197037 A is depleted in heavy elements compared to the Sun, with a metallicity Fe/H index of −0.16±0.03, but is younger at an age of 3.408±0.924 billion years.
CD-73°375 is a binary star located in the constellation Volans about 820 light years away. The two components, HR 2979 and HR 2980, are separated by two arc-seconds. The pair has a combined apparent magnitude of 6.34. It has a radial velocity of about 13 km/s, which means it drifting away from the Solar System.
HD 155448 is a quintuple star system consisting of 5 young B-type stars. With an apparent magnitude of 8.72, it is too dim to be visible with the naked eye.
GK Tauri is a young T Tauri-type pre-main sequence star in the constellation of Taurus about 421 light years away, belonging to the Taurus Molecular Cloud.
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.
HD 139319 is a ternary system composed of the binary Algol variable star known as TW Draconis, and a main-sequence companion star at a separation of 3 arcseconds. The system lies in the constellation of Draco about 540 light years away.
HR 4098, also known as HD 90508, is a binary star system in the northern constellation of Ursa Major at a distance of 75 light years. This object is barely visible to the naked eye as a dim, yellow star with an apparent visual magnitude of 6.45. It is approaching the Earth with a heliocentric radial velocity of 7.2±0.2 km/s.
HD 199223 is a double star in the equatorial constellation Delphinus. However, the system was originally in Equuleus prior to the creation of official IAU constellation borders. The components have a separation of 2″ at a position angle of 282° as of 2016. They have apparent magnitudes of 6.34 and 7.49 and distances of 354 and 359 light years respectively. The system is drifting closer with a radial velocity of −33 km/s.
S Cephei, also designated as HD 206362, is a carbon star and Mira-type variable in the constellation Cepheus. Based on the measurement of its annual parallax by the Gaia satellite, the star is approximately ∼1,590 ly away from Earth.