Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Cygnus |
A | |
Right ascension | 21h 08m 38.88974s [1] |
Declination | +30° 12′ 20.2879″ [1] |
Apparent magnitude (V) | 5.712 [2] |
B | |
Right ascension | 21h 08m 38.67181s [3] |
Declination | +30° 12′ 22.2133″ [3] |
Apparent magnitude (V) | 8.060 [2] |
Characteristics | |
Spectral type | B9V [4] (B9VspSi + kA2.5hA7VmA9n) [5] |
Variable type | Slowly pulsating B [6] |
Astrometry | |
A | |
Proper motion (μ) | RA: +24.645 [1] mas/yr Dec.: −20.647 [1] mas/yr |
Parallax (π) | 8.1988 ± 0.1038 mas [1] |
Distance | 398 ± 5 ly (122 ± 2 pc) |
B | |
Proper motion (μ) | RA: +24.004 [3] mas/yr Dec.: −25.161 [3] mas/yr |
Parallax (π) | 8.4500 ± 0.0263 mas [3] |
Distance | 386 ± 1 ly (118.3 ± 0.4 pc) |
Orbit [7] | |
Primary | Aa1 |
Companion | Aa2 |
Period (P) | 3.313 d |
Eccentricity (e) | 0 |
Semi-amplitude (K1) (primary) | 21.77 km/s |
Orbit [7] | |
Primary | Aa |
Companion | Ab |
Period (P) | 154.072 d |
Eccentricity (e) | 0.311 |
Semi-amplitude (K1) (primary) | 9.49 km/s |
Details | |
Aa1 | |
Mass | 3.17 [8] M☉ |
Radius | 2.5 [9] R☉ |
Luminosity | 113 [9] L☉ |
Surface gravity (log g) | 4.14 [9] cgs |
Temperature | 11,885 [9] K |
Rotation | 1.13 d [10] |
Rotational velocity (v sin i) | 17.9 [11] km/s |
Aa2 | |
Mass | 0.40 M☉ |
Ab | |
Mass | 0.65 M☉ |
B | |
Mass | 1.54 [8] M☉ |
Radius | 1.5 [9] R☉ |
Luminosity | 6.2 [9] L☉ |
Surface gravity (log g) | 4.33 [9] cgs |
Temperature | 7,482 [9] K |
Rotational velocity (v sin i) | 77 [11] km/s |
Other designations | |
Database references | |
SIMBAD | data |
A | |
B |
V389 Cygni, also known as HD 201433 and HR 8094, is a star about 390 light years from the Earth, in the constellation Cygnus. It is a 5th-magnitude star, making it faintly visible to the naked eye of an observer far from city lights. V389 Cygni is a multiple star. [4] One component of that system is a slowly pulsating B-type star (SPB) causing the system's brightness to vary from magnitude 5.55 to 5.71 over a period of 1.4 days. [6]
V389 Cygni is catalogued as a multiple star with four visible components. The faint companions TYC 2701-897-1 and UCAC4 602-123109 are unrelated background objects, [15] at 59″ and 73″ respectively. [16] A 5th-magnitude and 8th-magnitude star separated by 3.3″ form a common proper motion pair, generall referred to as components A and B). The brighter star, component A, is a spectroscopic binary and the system also harbours an unseen third star, making it a triple and the system as a whole then includes four stars. [8] Both the visible stars are chemically peculiar, A being an Ap star and B an Am star. [17] The blended spectral class of the pair is B9V, with the brighter star having a class of B9VspSi (or B9 Si Mg) [17] and the fainter kA2.5hA7VmA9n.
Component A of V389 Cygni was discovered to be a spectroscopic binary from spectra obtained in 1918. In 1921, Reynold K. Young of the Dominion Astrophysical Observatory derived its orbit from 49 additional spectra obtained in 1920-1921. He found it to have a circular orbit, with a period of 3.3137 days. He noted that the star showed evidence of variability. [13]
In 1922 Kurt Bottlinger and Paul Guthnick detected variability in V389 Cygni. [19] Between 1936 and 1942, Guthnick made extensive photoelectric observations of V389 Cygni. He found that sometimes the brightness appeared to change irregularly, and at other times two periods, 1.12912 and 1.19328 days, could be seen. Neither period was related to the orbital period of the spectroscopic binary. Guthnick postulated that the system consisted of two Cepheid variables orbiting each other, [20] [21] but it is now believed that only one of the stars in the close binary pair is variable, and it is an SPB star. [4]
In 1978, Frank Gieseking and Wilhelm Seggewiss refined Young's orbit determination for the spectroscopic binary (new period 3.313168±0.000008 days), and found that V389 Cygni is a triple star. The third, unseen component, orbits the close binary pair with a period of 154.09±0.02 days. They were unable to derive a nonzero eccentricity for either orbit. [19] In 1989, David Barlow re-analyzed earlier data and found that while the orbit of the inner binary appeared to be circular, the data were best fit if the orbit of the third star had an eccentricity of 0.311±0.057. [7]
In 2017, Thomas Kallinger et al. published an extensive spectroscopic and astroseismic study of V389 Cygni. They found 29 pulsation frequencies in the BRITE satellite data for the star. They were able to derive an eccentricity value for the inner binary pair's orbit of 0.015±0.003. Their astroseismic results indicate that the outer layer of the SPB star is in the process of becoming tidally locked to its close companion, but the inner portion of the star still rotates at a significantly different speed. [4]
70 Ophiuchi is a binary star system located 16.6 light years away from the Earth. It is in the constellation Ophiuchus. At magnitude 4 it appears as a dim star visible to the unaided eye away from city lights.
Epsilon Cancri is a white-hued binary star system in the zodiac constellation of Cancer. It is the brightest member of the Beehive Cluster with an apparent visual magnitude of +6.29, which is near the lower limit of visibility with the naked eye. The annual parallax shift of 5.4 mas as seen from Earth yields a distance estimate of approximately 606 light-years from the Sun.
Epsilon Volantis, Latinized from ε Volantis, is a quadruple star system in the southern constellation Volans. This star is at the center of the constellation of Volans and connects the "wings" of the constellation. Based upon parallax measurements, is roughly 640 light years from Earth.
74 Aquarii is a triple star system in the constellation of Aquarius. 74 Aquarii is its Flamsteed designation and it also bears the variable star designation HI Aquarii. The combined apparent visual magnitude is 5.8, although it is very slightly variable, and it is located at a distance of 590 light-years from Earth.
13 Vulpeculae is a blue giant with a stellar classification of class B9.5III in the northern constellation Vulpecula. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.57 and it is approximately 339 light years away from the Sun based on parallax. The star is radiating 180 times the luminosity of the Sun from its photosphere at an effective temperature of 8,801 K.
32 Cygni is the Flamsteed designation for a binary star system in the Cygnus constellation. It is a 4th magnitude star, which can be seen with the naked eye under suitably dark skies. Parallax measurements give an estimated distance of 1,100 light-years (320 parsecs) from the Earth. However, Schröder et al. (2007) suggest the actual value, after correcting for Malmquist bias, may be closer to 1,174 light-years (360 parsecs). Although it is a spectrsocopic binary with components that cannot be separated visually, it has two entries in the Henry Draper Catalogue, with identical magnitudes and positions, but showing the spectral types of the two components.
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.
LY Aurigae is a multiple star system in the constellation Auriga. It is an eclipsing binary variable star, dropping in brightness by 0.7 magnitudes every 4 days. The system is around a thousand light years away in the Auriga OB1 stellar association.
V381 Cephei is a triple star system in the northern constellation of Cepheus. Its apparent magnitude is slightly variable between 5.5 and 5.7.
Lambda Cygni is a class B5V star in the constellation Cygnus. Its apparent magnitude is 4.54 and it is approximately 770 light years away based on parallax.
ξ Cygni is a spectroscopic binary star in the constellation Cygnus. Its apparent magnitude is 3.73 and it is located around 360 parsecs (1,200 ly) away.
47 Cygni is a triple star system in the northern constellation of Cygnus, and is located around 4,000 light years from the Earth. It is visible to the naked eye with a combined apparent visual magnitude of 4.61. The system is moving closer to the Earth with a heliocentric radial velocity of −4.6 km/s.
μ Cygni, Latinised as Mu Cygni, is a binary star system in the northern constellation of Cygnus. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.49. The system is located 72 light years distant from the Sun, based on parallax, and is drifting further away with a radial velocity of +17 km/s.
𝜈 Pavonis, Latinized as Nu Pavonis, is a possible triple star system in the southern constellation of Pavo. It is visible to the naked eye as a faint star that varies in apparent visual magnitude from 4.60 to 4.64 over a period of 0.85584 days. The system lies approximately 440 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +17 km/s. It is a possible member of the Wolf 630 group of co-moving stars.
V Puppis is a star system in the constellation Puppis. Its apparent magnitude is 4.41. There is a binary star system at the center with a B1 dwarf orbiting a B3 subgiant star. They have an orbital period of 1.45 days and a distance of only 15 solar radii apart. However, the system moves back and forth, indicating that there is a massive object orbiting them with a period around 5.47 years. Based on the mass of the object, its lack of a visible spectrum, and circumstellar matter in the system with many heavy elements, it is probably a black hole. However, a follow-up study could not confirm this object, but found signs that there may be a third object which is fainter than the other components.
HY Velorum is a binary star system in the southern constellation of Vela. It is a dim star but visible to the naked eye with an apparent visual magnitude of 4.83. The distance to this system, as estimated from its annual parallax shift of 7.1 mas, is 460 light years. HY Vel most likely forms a gravitationally bound pair with the magnitude 5.45 binary system KT Vel ; both are members of the IC 2391 open cluster. As of 1998, HY Vel and KT Vel had an angular separation of 76.1″ along a position angle of 311°.
31 Cygni, also known as ο1 Cygni, Omicron1 Cygni, ο2 Cygni or V695 Cygni, is a ternary star system about 750 light years away in the constellation Cygnus.
EQ Pegasi is a nearby binary system of two red dwarfs. Both components are flare stars, with spectral types of M4Ve and M6Ve respectively, and a current separation between the components of 5.8 arcseconds. The system is at a distance of 20.4 light-years, and is 950 million years old. The primary star is orbited by one known exoplanet.
HR 7484 is a binary star system in the northern constellation of Cygnus. It is dimly visible to the naked eye under good viewing conditions, having an apparent visual magnitude of 5.89. Based upon an annual parallax shift of 24.71, it is located 132 light years away. The system is moving closer with a heliocentric radial velocity of −14 km/s.
7 Tauri is a multiple star in the northern constellation of Taurus. It has a combined apparent visual magnitude of 5.95, so, according to the Bortle scale, it is faintly visible from suburban skies at night. Measurements made with the Gaia spacecraft show an annual parallax shift of 5.5 mas, which is equivalent to a distance of around 593 light years from the Sun.