| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 04h 20m 16.764s[2] |
| Declination | +42° 18′ 51.81″[2] |
| Apparent magnitude (V) | 9.68 min1: 11.36 min2: 9.78[3] |
| Characteristics | |
| Spectral type | B9.6e + K2III-IV[4][5] |
| Variable type | Semi-detachedAlgol variable[1] |
| Astrometry | |
| Radial velocity (Rv) | 5.8±2.7[6] km/s |
| Proper motion (μ) | RA: −3.965mas/yr[2] Dec.: −5.345mas/yr[2] |
| Parallax (π) | 2.163±0.0343 mas[2] |
| Distance | 1,510 ± 20 ly (462 ± 7 pc) |
| Absolute magnitude (MV) | +0.4/+1.6[7] |
| Orbit | |
| Period (P) | 13.198949 d[8] |
| Eccentricity (e) | 0.00[9] |
| Inclination (i) | 81.56[7]° |
| Periastronepoch (T) | 2,416,032.0070 JD[9] |
| Semi-amplitude (K1) (primary) | 18.5[9] km/s |
| Semi-amplitude (K2) (secondary) | 6.5[9] km/s |
| Details[7] | |
| Primary | |
| Mass | 2.56 M☉ |
| Radius | 2.8 R☉ |
| Luminosity | 62 L☉ |
| Temperature | 9,700 K |
| Secondary | |
| Mass | 0.38 M☉ |
| Radius | 7.3 R☉ |
| Luminosity | 33 L☉ |
| Temperature | 4,200 K |
| Other designations | |
| BE Cet,BD+41°851,HD 276247,HIP 20245[10] | |
| Database references | |
| SIMBAD | data |
RW Persei is aeclipsing binary[4] star system in the northernconstellation ofPerseus. It has a peakapparent visual magnitude of 9.68,[3] so this system is too faint to be viewed with the naked eye. During the primary eclipse the brightness decreases to magnitude 11.36, but only to magnitude 9.78 with the secondary eclipse. The distance to RW Persei is approximately 1,510 light years, based onparallax measurements.[2] It is receding from theSun with aradial velocity of5.8±2.7 km/s.[6]
The variability of this star was discovered bySigurd Enebo, for which he received the 1906 Lindemann Award from theAstronomische Gesellschaft. He classified it as anAlgol variable and found a period of 13.196 days. Enebo refined the period to 13.1989 days in 1910.[11] The low brightness and relatively long period of this system meant that it received little study for many decades.[5] In 1945,O. Struve foundemission lines, but (except for theH-alpha emission lines) only during an eclipse. It has a deep primary eclipse with only a minor secondary eclipse. He interpreted the emission as a nebulous stream moving with the eclipsed star.[9]
D. S. Hall noted a rapid decrease in the duration of the primary eclipse in 1967, becoming apartial eclipse.[12] Observations made in 1974 suggested a possible period change in the eclipse cycle.[13] In 1986,J. J. Dobias andM. J. Plavec determined the primary component to be aBe star with an optically thick accretion disk in orbit.[5] The secondary is an ordinary K2giant star.[14] Subsequent observations in 1988 and 1989 failed to confirm this disk, although they did show that the primary component must be spinning at 30 times the rate ofsynchronous rotation.[15]
In 1991, the eclipse amplitude was found to have changed multiple times, declining from a magnitude difference of 3.20 in 1900 down to 1.75 in blue light. This is the second system shown to undergo such large adjustments in eclipse amplitude afterIU Aurigae. The changes suggested a wobble in theorbital plane caused by an orbiting third body in the system. Alterations in theO–C diagram supported this interpretation, giving anorbital period of 68 years for the third body.[14] However, aphotometric study in 1992 failed to confirm the presence of a third body in the system. Instead, it was proposed that changes in the polar radius of the primary, brought on byaccretion and slowed rotation, may explain the variations.[1]
