![]() Light curves for DO Draconis. The upper plot, adapted from Andronov et al., [1] shows the long-term variability and eruptive behaviour. The lower plot, adapted from Hill et al., [2] shows the ellipsoidal variability assuming a period of 3.96898 hours. | |
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Draco |
Right ascension | 11h 43m 38.492s [3] |
Declination | +71° 41′ 20.56″ [3] |
Apparent magnitude (V) | 10.0 to 15.1 [4] |
Characteristics | |
Spectral type | + dM4 [5] |
Variable type | U Gem [4] |
Astrometry | |
Proper motion (μ) | RA: 14.379 mas/yr [3] Dec.: 12.772 mas/yr [3] |
Parallax (π) | 5.1049 ± 0.0278 mas [3] |
Distance | 639 ± 3 ly (196 ± 1 pc) |
Orbit | |
Period (P) | 3.968982 h [6] |
Semi-major axis (a) | 1.35±0.15 R☉ [5] |
Inclination (i) | 41±3 [6] ° |
Semi-amplitude (K1) (primary) | 87±13 [5] km/s |
Semi-amplitude (K2) (secondary) | 184±10 [5] km/s |
Details | |
Accreting white dwarf | |
Mass | 0.83±0.10 [7] M☉ |
Temperature | 21,500 [8] K |
Rotation | 529.31±0.02 s [7] |
Donor red dwarf | |
Mass | 0.375±0.014 [7] M☉ |
Radius | 0.42±0.08 [5] R☉ |
Rotational velocity (v sin i) | 86±15 [5] km/s |
Other designations | |
Database references | |
SIMBAD | data |
YY Draconis and DO Draconis are separate identifiers for what is likely the same cataclysmic variable system in the northern constellation of Draco, abbreviated YY Dra and DO Dra, respectively. The DO Dra binary star system is classified as a U Geminorum variable that ranges in luminosity from an apparent visual magnitude of 10.0 down to 15.1. [4] It is located at a distance of approximately 639 light years from the Sun. [3]
The variable YY Draconis was identified by W. Tsesevich in 1934 and determined to be an Algol type binary that ranged in brightness from apparent magnitude 12.9 to under 14.5 with a period of 4.21123 days. However, subsequent scans of photographic plates at the same coordinates have failed to identify any such variation. Hence, a positional reporting error is suspected, [10] and no further observations of this variable were reported (as of 1983). [11]
In 1982, the X-ray emission source PG 1148+719 (3A 1148+719) was associated with a star displaying the spectrum of a U Geminorum variable by R. F. Green and associates. In their paper, they identified this star as YY Dra, based on a positional search of the General Catalogue of Variable Stars . [12] The following year, W. Wenzel found the association with YY Dra appeared erroneous but discovered a nearby eruptive variable that brightened to magnitude 10.6 then dimmed to below magnitude 14.5. He estimated a lengthy cycle time of 5 to 20 years, comparable to BZ Ursae Majoris. [11] This cataclysmic variable was cataloged as DO Draconis.
An outburst of DO Dra was observed while in progress in 1985, which brought the system to about a magnitude brighter than minimum. [13] [14] In 1987, a debate arose as to whether this is the same variable as YY Dra, as the coordinates are separated by only 53″. [10] [15] Discussion of this identity conflict has continued as recently as 2022, and, historically, both identifiers have been used to discuss the same cataclysmic variable. A full resolution of this conflict may prove impossible since many of the original photographic plates were destroyed during World War II. The continued use of DO Dra for this variable has been encouraged since it is an unambiguous identifier. [16]
In 1991, M. Mateo and associates found an orbital period of 3.96 h with a semimajor axis of 1.35±0.15 R☉ for this binary system. DO Dra consists of a compact white dwarf primary being orbited by a red dwarf stellar companion. The red dwarf has filled its Roche lobe and is losing mass, which is being accreted by the white dwarf. Because of the close orbit, the red dwarf is rotating rapidly and is expected to be magnetically active. However, the majority of the ionized calcium emission lines originate from irradiation of the red dwarf by soft X-rays coming from the primary. [5]
This system was identified as a DQ Herculis variable by J. Patterson and associates in 1994 – also known as an intermediate polar. This indicates the white dwarf has a sufficiently strong magnetic field to channel the flow of gas from an orbiting accretion disk onto its magnetic poles. The shock from this accretion is producing the X-ray flux. [17] A 1997 study based on observations with the Hubble Space Telescope found a rotation period of 529.31±0.02 s for the white dwarf. This spin rate is producing coherent pulsations that are detectable in both the visual and X-ray spectrum. [7] The magnetic poles reach effective temperatures of 220,000 K in the accretion region, compared to 21,500 K for the remainder of the white dwarf surface. [8]
DQ Herculis, or Nova Herculis 1934, was a slow, bright nova occurring in the northern constellation of Hercules in December 1934. This cataclysmic variable star was discovered on 13 December 1934 by J. P. M. Prentice from Stowmarket, Suffolk. It reached peak brightness on 22 December 1934 with an apparent magnitude of 1.5. The nova remained visible to the naked eye for several months.
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.
WZ Sagittae is a cataclysmic dwarf nova star system in the constellation Sagitta. It consists of a white dwarf primary being orbited by a low mass companion. The white dwarf is about 0.85 solar masses while the companion is only 0.08 solar masses. This implies that the companion is a spectral class L2 star, although this has yet to be confirmed. The distance to this system has been determined by parallax, yielding a distance of 45.1 parsecs.
RX Andromedae is a variable star in the constellation of Andromeda. Although it is classified as a dwarf nova of the Z Camelopardalis (UGZ) type, it has shown low-luminosity periods typical of VY Sculptoris stars. However, for most of the time it varies from an apparent visual magnitude of 15.1 at minimum brightness to a magnitude of 10.2 at maximum brightness, with a period of approximately 13 days.
CE Gruis is a faint binary star system in the constellation Grus. It is a variable star, with a B-band brightness that ranges from a peak magnitude of 17.4 down to a minimum of 19.5 over a period of 108.6 minutes. The system is composed of a white dwarf and donor star, locked into a close, synchronous orbit. In such systems, known as polars, material from the donor star does not form an accretion disc around the white dwarf because of its intense magnetic field, but rather streams directly onto it along columns.
QS Telescopii is a faint, well-studied binary star system in the southern constellation Telescopium. It is composed of a white dwarf and main sequence donor star, locked into a close, circular orbit facing one another. Known as polars, material from the donor star does not form an accretion disk around the white dwarf, but rather streams directly onto it. This is due to the presence of the white dwarf's strong magnetic field. The pair undergo frequent shifts between a high and low accretion states, and it shifts between single and double accretion poles. The main pole is partially self-eclipsing.
SW Sextantis variable stars are a kind of cataclysmic variable star; they are double-star systems in which there is mass transfer from a red dwarf to a white dwarf forming a stable accretion disc around the latter. Unlike other non-magnetic cataclysmic variables, the emission lines from hydrogen and helium are not doubled, except briefly near phase 0.5.
BV Centauri is a cataclysmic variable binary star in the constellation Centaurus. It is a dwarf nova, and undergoes rapid increases in brightness that are recurrent with a mean period of 150 days. This period seems to have increased in the last few decades. During quiescence, its visual apparent magnitude is about 13, with variations of a few tenths of magnitude over an orbit due to differences in the star's visible surface area, brightening to a maximum magnitude of 10.7 during outbursts. From its luminosity, it is estimated that the system is about 500 parsecs (1,600 ly) away from Earth. A Gaia parallax of 2.81 mas has been measured, corresponding to about 360 pc.
SU Ursae Majoris, or SU UMa, is a close binary star in the northern circumpolar constellation of Ursa Major. It is a periodic cataclysmic variable that varies in magnitude from a peak of 10.8 down to a base of 14.96. The distance to this system, as determined from its annual parallax shift of 4.53 mas, is 719 light-years. It is moving further from the Earth with a heliocentric radial velocity of +27 km/s.
V455 Andromedae is a dwarf nova in the constellation Andromeda. It has a typical apparent visual magnitude of 16.5, but reached a magnitude of 8.5 during the only observed outburst.
V1315 Aquilae is a cataclysmic variable star in the north of the equatorial constellation of Aquila. It is in the sub-set of nova-like (NL) variables, specifically a SW Sextantis star. These were characterized as having non-magnetic white dwarfs – thus that do not undergo dwarf-nova bright luminations ("eruptions"). There is countering evidence for some magnetism. Being a SW Sextantis star, V1315 Aquilae has a high rate of mass transfer, so it is in steady-state accretion and in a constant state of outburst. It emits most of its light in the visible range, and this comes from the accretion disk. The eclipse depth is 1.8 mag. No description of the donor star is made.
GI Monocerotis, also known as Nova Monocerotis 1918, was a nova that erupted in the constellation Monoceros during 1918. It was discovered by Max Wolf on a photographic plate taken at the Heidelberg Observatory on 4 February 1918. At the time of its discovery, it had a photographic magnitude of 8.5, and had already passed its peak brightness. A search of plates taken at the Harvard College Observatory showed that it had a photographic magnitude of 5.4 on 1 January 1918, so it would have been visible to the naked eye around that time. By March 1918 it had dropped to ninth or tenth magnitude. By November 1920 it was a little fainter than 15th magnitude.
BZ Ursae Majoris is a dwarf nova star system in the northern circumpolar constellation of Ursa Major. It consists of a white dwarf primary in a close orbit with a red dwarf. The latter star is donating mass, which is accumulating in an accretion disk orbiting the white dwarf. The system is located at a distance of approximately 505 light years from the Sun based on parallax measurements.
BG Canis Minoris is a binary star system in the equatorial constellation of Canis Minor, abbreviated BG CMi. With an apparent visual magnitude that fluctuates around 14.5, it is much too faint to be visible to the naked eye. Parallax measurements provide a distance estimate of approximately 2,910 light years from the Sun.
QQ Vulpeculae is a cataclysmic variable binary star system in the northern constellation of Vulpecula, abbreviated QQ Vul. It has a brightness that fluctuates around an apparent visual magnitude of 14.7, which is too faint to be viewed with the naked eye. The distance to this system is approximately 981 light years based on parallax measurements.
SW Ursae Majoris is a cataclysmic binary star system in the northern circumpolar constellation of Ursa Major, abbreviated SW UMa. During quiescence it has an apparent visual magnitude of 16.5–17, which is too faint to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 526 light years from the Sun.
DW Ursae Majoris is an eclipsing binary star system in the northern circumpolar constellation of Ursa Major, abbreviated DW UMa. It is a cataclysmic variable of the SX Sextanis type, consisting of a compact white dwarf that is accreting matter from an orbiting companion star. The brightness of this source ranges from an apparent visual magnitude of 13.6 down to magnitude 18, which is too faint to be viewed with the naked eye. The distance to this system is approximately 1,920 light years based on parallax measurements.
ER Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated ER UMa. It is a prototype system for a subclass of SU Ursae Majoris dwarf novae. The system ranges in brightness from a peak apparent visual magnitude of 12.4 down to 15.2, which is too faint to be visible to the naked eye. The distance to this system, based on parallax measurements, is approximately 1,163 light years.
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.
IW Andromedae is a binary star system in the northern constellation of Andromeda, abbreviated IW And. It is the prototype of a class of variable stars known as IW And variables, which is an anomalous sub-class of the Z Camelopardalis variables. The brightness of this system ranges from an apparent visual magnitude of 13.7 down to 17.3, which requires a telescope to view. The system is located at a distance of approximately 2,860 light years from the Sun based on parallax measurements.