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]
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]