DW Cancri
Variable star in constellation Cancer
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DW Cancri (DW Cnc) is a cataclysmic variable (CV) star system located in the constellation of Cancer.[1] It is classified as an intermediate polar (IP), a subtype of magnetic CV characterized by a white dwarf primary with a moderately strong magnetic field that channels accretion from a low-mass companion star.[4][5] The system exhibits behaviors typical of VY Scl-type variables, including prolonged low states and occasional brightenings.[6] DW Cnc has an orbital period of approximately 86 minutes, placing it below the period gap for CVs.[4][5]
| |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 07h 58m 53.04s[1] |
| Declination | +16° 16′ 45.2″[1] |
| Apparent magnitude (V) | 11.36 - 16.3[2] |
| Characteristics | |
| Evolutionary stage | White dwarf + Red dwarf |
| Variable type | U Gem[2] |
| Astrometry | |
| Radial velocity (Rv) | 38.970486[1] km/s |
| Proper motion (μ) | RA: -25.973[1] mas/yr Dec.: -0.142[1] mas/yr |
| Parallax (π) | 4.8818±0.0395 mas[3] |
| Distance | 668 ± 5 ly (205 ± 2 pc) |
| Other designations | |
| DW Cnc, AAVSO 0753+16, TIC 19028616[1] | |
| Database references | |
| SIMBAD | data |
Discovery
DW Cancri was identified as a potential CV during the Byurakan survey for blue galaxies and quasars, where it appeared as an emission-line object due to strong Balmer series lines in its spectrum.[4] Further spectroscopic confirmation established it as a CV, with initial studies noting its nova-like characteristics and lack of typical dwarf nova outbursts. The system's magnetic nature was inferred from periodic photometric and spectroscopic modulations consistent with an intermediate polar.[4]
Characteristics
DW Cnc is a close binary system consisting of a white dwarf primary and a low-mass main-sequence secondary, likely a red dwarf, from which material is accreted via Roche lobe overflow.[4][5] The white dwarf's magnetic field, estimated to be moderately strong, disrupts the inner accretion disk and funnels material to its magnetic poles, producing characteristic spin-period modulations.[4]
Variability
DW Cnc displays two distinct states: a high state at V ≈ 14.5–15 magnitude and prolonged low states ≈2 magnitudes fainter (V ≈ 16.5–17.5), characteristic of VY Scl stars where reduced mass transfer dims the system.[7][6] In low states, the accretion disk may be depleted, weakening periodic signals like the spin period.[5]
The first observed outburst occurred in 2007, brightening by ≈4 magnitudes to V ≈ 11.36 before fading ≈2.25 magnitudes in 27 hours.[8] More recent observations identified three short high-state outbursts lasting ≈1 day each, with a recurrence time of ≈60 days and amplitude ≈1 magnitude, potentially magnetically gated.[7] These events contrast with the typical quiescence of intermediate polars and suggest episodic mass transfer enhancements.[5]
Kilo-second quasi-periodic oscillations (QPOs) have been detected, with continuous signals over 61 days, interpreted as accretion instabilities or disk modes.[9]