Observation data Epoch J2000.0 [1] Equinox J2000.0 [1] | |
---|---|
Constellation | Sagittarius |
Right ascension | 19h 07m 09.77940s |
Declination | −26° 19′ 54.5064″ |
Apparent magnitude (V) | 9.15 [2] |
Characteristics | |
Evolutionary stage | A5 SrEuCr [3] |
B−V color index | 0.45 [2] |
J−H color index | 0.071 [4] |
J−K color index | 0.055 [4] |
Astrometry | |
Proper motion (μ) | RA: -2.063 [1] mas/yr Dec.: −4.425 [1] mas/yr |
Parallax (π) | 2.5411 ± 0.0186 mas [1] |
Distance | 1,284 ± 9 ly (394 ± 3 pc) |
Absolute magnitude (MV) | 1.55, [5] 1.166 [6] |
Details [5] | |
Mass | 1.81, 2.2 [7] M☉ |
Radius | 2.57 R☉ |
Luminosity | 18.9, 26.9, [6] ~32 [7] L☉ |
Surface gravity (log g) | 3.79 cgs |
Temperature | 7420, 7002, [6] 8000 [7] K |
Rotational velocity (v sin i) | 2.50 [8] km/s |
Age | 955 Myr |
Other designations | |
Database references | |
SIMBAD | data |
HD 177765 is a white-hued star in the southern constellation of Sagittarius. With an apparent magnitude of 9.15, it is too faint to be seen by the naked eye from Earth, but is dimly visible using binoculars. [9] It is located at a distance of 1,284 light-years (394 parsecs) according to Gaia EDR3 parallax measurements.
The star is classified as a rapidly oscillating Ap star (roAp star). It shows super-solar abundances of chromium and strontium as well as many rare-earth elements such as europium and cerium, but is depleted of carbon and nickel. [8] In 2012, the star was found to pulsate with a low radial velocity amplitude of 7–150 m/s and a period of 23.6 minutes, the latter being the longest out of any known roAp star at the time. [7] Two additional pulsation frequencies were detected in 2016. [10]
The precise stellar parameters vary from publication to publication, but the star is considered to be part of a group of evolved roAp stars with long pulsation periods, alongside β CrB A and HD 116114. The existence of this group implies a systematic shift of rare-earth emission line anomalies as roAp stars age. [7]
HD 1185 is a double star in the northern constellation of Andromeda. The primary, with an apparent magnitude of 6.15, is a white main-sequence star of spectral type A2VpSi, indicating it has stronger silicon absorption lines than usual, thus making it also an Ap star. The secondary companion, which is 9.08 arcseconds away, is not visible to the naked eye at an apparent magnitude of 9.76. It shares common proper motion and parallax with the primary star but orbital parameters are still unknown.
HD 30442 is a solitary star in the northern circumpolar constellation Camelopardalis. It is faintly visible to the naked eye with an apparent magnitude of 5.47 and is estimated to be 403 light years away from the Solar System. The object has a heliocentric radial velocity of −37 km/s, indicating that it is drifting closer.
20 Camelopardalis is a solitary star in the circumpolar constellation Camelopardalis. It has an apparent magnitude of 7.45, making it readily visible in binoculars but not to the naked eye. Located about 880 light years away, it is approaching the Solar System with a radial velocity of −50.3 km/s. Due to its faintness, 20 Cam is one of the 220 Flamsteed stars without Bright Star Catalog designations.
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.
HD 166066 is a solitary star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 8.10, making it readily visible in binoculars, but not to the naked eye. The object is located 223 light years away from the Solar System, but is drifting away with a poorly constrained radial velocity of about 2.93 km/s.
HD 76270, also known as HR 3544, is a solitary, white hued star located in the southern circumpolar constellation Volans. It has an apparent magnitude of 6.10, making it faintly visible to the naked eye if viewed under ideal conditions. The object is relatively far with a distance of 2,360 light years, but is slowly approaching the Solar System with a heliocentric radial velocity of −2.6 km/s.
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.
HD 1, also known as HIP 422, is the first star catalogued in the Henry Draper Catalogue. It is located in the northern circumpolar constellation Cepheus and has an apparent magnitude of 7.42, making it readily visible in binoculars, but not to the naked eye. The object is located relatively far away at a distance of 1,220 light years but is approaching the Solar System with a spectroscopic radial velocity of −27.3 km/s.
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.
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.
HD 193721 is an astrometric binary in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.77, allowing it to be faintly seen with the naked eye. Parallax measurements place the system 760 light years away from the Solar System and it is currently receding with a heliocentric radial velocity 8.6 km/s.
HD 193373 is a solitary red hued star located in the equatorial constellation Delphinus. It has an apparent magnitude of 6.21, placing it near the limit for naked eye visibility. Parallax measurements place it 846 light years distant and it is currently receding with a heliocentric radial velocity of 22.7 km/s.
HD 194612 is a solitary orange hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.9, making it visible to the naked eye under ideal conditions. Parallax measurements place it at a distance of 760 light years and it has a low heliocentric radial velocity of 0.3 km/s.
HD 182509, also designated as HR 7370, is an orange hued star located in the southern constellation Telescopium. It has an apparent magnitude of 5.69, making it faintly visible to the naked eye if viewed under ideal conditions. Parallax measurements place the object at a distance of 635 light years. It has a poorly constrained heliocentric radial velocity of −5 km/s, indicating that it is drifting towards the Solar System.
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.
HD 166473 is a rapidly oscillating Ap star and an α2 CVn variable located about 455 light-years away in the southern constellation of Corona Australis. It has the variable star designation V694 Coronae Australis. With an apparent magnitude of 7.953, it is too faint to be seen by the naked eye from Earth, but can be observed using binoculars.
HD 861 is a spectroscopic binary star system in the deep northern constellation of Cassiopeia. With an apparent magnitude of 6.622, the star is faintly visible to the naked eye under very dark skies and readily visible using binoculars. It is located approximately 403 light-years distant according to Gaia EDR3 parallax measurements, and is moving further away at a heliocentric radial velocity of 8.80 km/s.
HD 197911 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. The star is located some 3,020 light-years 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.
HD 24733 is a spectroscopic binary system that is also a Beta Lyrae variable located about 606 light-years away in the deep northern constellation of Camelopardalis, close to the border with Perseus. It has the variable-star designation DD Camelopardalis. With a mean apparent magnitude of 7.038, it is too faint to be seen by the naked eye from Earth, but readily visible through binoculars.