Light curves for CX Draconis. The main plot, from Hipparcos data, [1] shows the long-term variability. The inset plot, from TESS data, [2] shows how the brightness changes of short timescales. | |
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Draco |
Right ascension | 18h 46m 43.089s [3] |
Declination | +52° 59′ 16.65″ [3] |
Apparent magnitude (V) | 5.68 to 5.99 [4] |
Characteristics | |
Spectral type | B2.5 V + F5 III [5] |
Variable type | γ Cas + rotating ellipsoidal [4] |
Astrometry | |
Radial velocity (Rv) | −2.1±2.3 [6] km/s |
Proper motion (μ) | RA: 10.965 mas/yr [3] Dec.: −4.920 mas/yr [3] |
Parallax (π) | 2.8262 ± 0.0587 mas [3] |
Distance | 1,150 ± 20 ly (354 ± 7 pc) |
Orbit [7] | |
Period (P) | 6.695957±0.000043 d |
Semi-major axis (a) | ≥ 3.253 Gm [8] |
Eccentricity (e) | 0.052±0.006 |
Inclination (i) | 52 to 55° |
Periastron epoch (T) | 2,442,549.48±0.24 HJD |
Argument of periastron (ω) (secondary) | 267.9±6.4° |
Semi-amplitude (K1) (primary) | 33.66±0.86 km/s |
Semi-amplitude (K2) (secondary) | 145.92±0.82 km/s |
Details | |
Primary | |
Mass | 7.3 [9] M☉ |
Surface gravity (log g) | 3.71±0.27 [10] cgs |
Temperature | 19,580±640 [10] K |
Rotational velocity (v sin i) | 163±10 [10] km/s |
Secondary | |
Mass | ~1.7 [9] M☉ |
Temperature | 6,500 [11] K |
Rotational velocity (v sin i) | ~65 [11] km/s |
Other designations | |
Database references | |
SIMBAD | data |
CX Draconis is an interacting binary star system in the northern constellation of Draco, abbreviated CX Dra. It has the designation HD 174237 in the Henry Draper Catalogue ; CX Draconis is the variable star designation. This is a double-lined spectroscopic binary system with a near circular orbit. [7] The brightness of the system undergoes long-term irregular fluctuations, [11] ranging from an apparent visual magnitude of 5.68 down to 5.99. [4] Based on parallax measurements, it is located at a distance of approximately 1,150 light years from the Sun. [3]
In 1921, this target was found to have a varying radial velocity by J. S. Plaskett and associates. [13] [14] It was shown to be a Be star by O. C. Mohler in 1940, [15] and in 1965 M. Lacoarret studied variations in the hydrogen alpha emission profiles from the target. This system was discovered to be a photometric variable by P. Merlin in 1975. [14] P. Koubský measured the radial velocity variations in 1976, [16] and in 1978 published orbital elements for this binary system with a period of 6.696 days. [17] He found that the variation in emission lines matched the time scale of the orbit, indicating that this is an interacting binary. [11]
Using observations from the Einstein Observatory, in 1984 this system was shown to be an X-ray source by E. F. Guinan and associates. This emission may be coming from the cooler secondary that is phase-locked with the primary and is magnetically active due to rapid rotation. [18] In 1992, J. Horn and associates determined that the secondary component is an evolved F-type giant star. Evidence suggests this star is overflowing its Roche lobe with gas streaming toward the primary. [11]
Models indicate that the main source of the H-alpha emission is located mid-way between the two stars, with other emission lines originating from an accretion disk orbiting the primary. The circumstellar environment is changing in cycles lasting hundreds of days. [7] Infrared emission to the northeast of the system suggests it may be undergoing systematic mass loss. [19]
Beta Canis Minoris, also named Gomeisa, is a star in the constellation of Canis Minor. In the night sky it is notable for its proximity to the prominent star Procyon.
Upsilon Sagittarii is a spectroscopic binary star system in the constellation Sagittarius. Upsilon Sagittarii is the prototypical hydrogen-deficient binary (HdB), and one of only four such systems known. The unusual spectrum of hydrogen-deficient binaries has made stellar classification of Upsilon Sagittarii difficult.
Zeta Tauri is a binary star in the zodiac constellation of Taurus, the Bull. It has an apparent visual magnitude of about 3.0, which is bright enough to be seen with the naked eye. Parallax measurements place it at a distance of roughly 440 light-years from the Sun.
Nu Draconis is a double star in the constellation Draco. The respective components are designated ν1 Draconis and ν2 Draconis. The second component is a spectroscopic binary star system.
26 Andromedae, abbreviated 26 And, is a binary star system in the constellation Andromeda. 26 Andromedae is the Flamsteed designation. It has a combined apparent visual magnitude of 6.10, which is near the lower limit of visibility to the naked eye. The distance to this system can be estimated from its annual parallax shift of 5.35 mas, which yields a distance of about 600 light years. At that distance, the visual magnitude of the stars is diminished from an extinction of 0.04 due to interstellar dust. The system is moving further from the Earth with a heliocentric radial velocity of +3.3 km/s.
Kappa Draconis, Latinized from κ Draconis, is a blue giant star located in the northern circumpolar constellation of Draco. At an apparent magnitude of 3.88, it is barely visible to the naked eye when artificial lighting from cities is present. Nevertheless, it is a powerful star, approximately five time as massive as the Sun. It is about 460 light-years away, and is 1,400 times brighter than the Sun.
Chi Draconis is a magnitude 3.6 binary star in the constellation Draco. It also has the Flamsteed designation 44 Draconis. At a distance of 27 light years, it is one of the forty or so closest stars.
Phi Persei is a class B2Vep fourth-magnitude star in the constellation Perseus, location about 720 light-years from Earth.
Omicron Draconis is a giant star in the constellation Draco located 322.93 light years from the Earth. Its path in the night sky is circumpolar for latitudes greater than 31o north, meaning the star never rises or sets when viewed in the night sky.
AG Draconis is a binary star system in the northern constellation of Draco. It consists of a giant star and a white dwarf that revolve around each other every 550 days.
V923 Aquilae is a variable binary star system in the equatorial constellation of Aquila. It has the designation HD 183656 from the Henry Draper Catalogue; V932 Aql is the variable star designation. The system is dimly visible to the naked eye with an apparent visual magnitude that fluctuates around 6.06. It is located at a distance of approximately 890 light years from the Sun based on parallax, but is drifting closer with a radial velocity of around −26 km/s.
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.
Theta Draconis, a name Latinized from θ Draconis, is a binary star system in the northern circumpolar constellation of Draco. It is faintly visible to the naked eye at night with an apparent visual magnitude of 4.12. Parallax measurements place it at an estimated distance of 68.6 light-years from the Sun, and it is drifting closer with a radial velocity of −8 km/s. It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.464″ per year. O. J. Eggen included this star as a member of the NGC 1901 supercluster based on its space motion.
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59 Cygni is a multiple star system in the northern constellation of Cygnus, located roughly 1,300 light years away from Earth. It is visible to the naked eye as a blue-white hued star with a combined apparent visual magnitude of 4.74.
14 Lacertae is a binary star system in the northern constellation Lacerta, located around 1,600 light years away. It has the variable star designation V360 Lacertae; 14 Lacertae is the Flamsteed designation. The system is barely visible to the naked eye in good seeing conditions, having a peak apparent visual magnitude of 5.91. It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.
50 Persei is a star in the constellation Perseus. Its apparent magnitude is 5.52, which is bright enough to be seen with the naked eye. Located around 21.00 parsecs (68.5 ly) distant, it is a White main-sequence star of spectral type F7V, a star that is currently fusing its core hydrogen. In 1998 the star was named a candidate Gamma Doradus variable with a period of 3.05 days, which would means it displays variations in luminosity due to non-radial pulsations in the photosphere. Subsequently, it was classified as a RS Canum Venaticorum and BY Draconis variable by an automated program.
λ Librae is the Bayer designation for a binary star system in the zodiac constellation of Libra. It can be faintly seen with the naked eye, having an apparent visual magnitude of 5.03. With an annual parallax shift of 10.54 mas, it is roughly 310 light years from the Sun. At that distance, the visual magnitude of this system is diminished by an extinction factor of 0.22 due to interstellar dust. It is 0.1 degree north of the ecliptic.
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.
4 Draconis, also known as HR 4765 and CQ Draconis, is a star about 570 light years from the Earth, in the constellation Draco. 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 4.90 to 5.12 over a period of 4.66 years.