| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Serpens |
| Right ascension | 15h 58m 18.410s [2] |
| Declination | +17° 16′ 10.00″ [2] |
| Apparent magnitude (V) | 11.04±0.09 [3] |
| Characteristics | |
| Spectral type | A2 [4] |
| B−V color index | 0.22 [3] |
| Variable type | β Per + δ Sct [5] |
| Astrometry | |
| Primary | |
| Proper motion (μ) | RA: −8.236 mas/yr [2] Dec.: −10.444 mas/yr [2] |
| Parallax (π) | 2.2539±0.0229 mas [2] |
| Distance | 1,450 ± 10 ly (444 ± 5 pc) |
| Absolute magnitude (MV) | +1.88±0.03 |
| Secondary | |
| Absolute magnitude (MV) | +5.17±0.05 |
| Orbit [5] | |
| Period (P) | 0.8793496±0.0000047 d |
| Semi-major axis (a) | 5.59±0.05 R☉ |
| Inclination (i) | 90.0±1.5° |
| Longitude of the node (Ω) | 3.645±0.002° |
| Periastron epoch (T) | 2,457,127.5076±0.0041 HJD |
| Semi-amplitude (K1) (primary) | 51.6±1.1 km/s |
| Semi-amplitude (K2) (secondary) | 270.3±3.6 km/s |
| Details [5] | |
| Primary | |
| Mass | 2.55±0.09 M☉ |
| Radius | 1.64±0.02 R☉ |
| Luminosity | 14.45+0.69 −0.65 L☉ |
| Surface gravity (log g) | 4.42±0.01 cgs |
| Temperature | 8,820±62 K |
| Rotational velocity (v sin i) | 90±18 km/s |
| Secondary | |
| Mass | 0.49±0.02 M☉ |
| Radius | 1.38±0.02 R☉ |
| Luminosity | 0.93+0.05 −0.04 L☉ |
| Surface gravity (log g) | 3.85±0.01 cgs |
| Temperature | 4,786±11 [4] K |
| Other designations | |
| AO Ser, BD+17°2942, TYC 1496-3-1, GSC 01496-00003, 2MASS J15581840+1716101 [6] | |
| Database references | |
| SIMBAD | data |
AO Serpentis is an eclipsing binary star system in the Serpens Caput segment of the Serpens constellation. It is invisible to the naked eye with a typical apparent visual magnitude of 11.04. [3] Variable star observers record a peak magnitude of 10.7, dropping to 12.0 during the primary eclipse and 10.8 from the secondary eclipse. [7] The distance to this system is approximately 1,450 light years based on parallax measurements. [2]
This system was discovered by C. Hoffmeister to be an Algol-type eclipsing binary in 1935. [8] The following year, P. Guthnick and R. Prager reported a brightness variation between 10.5 and 12.0. [9] In 2004, S. -L. Kim and associates determined that one of the components of this system is pulsating with a short period. [10]
This is a semi-detached binary star system with the secondary component completely filling its Roche lobe while the primary is 61% full. It has an orbital period of 21.1 hours and a semimajor axis of just 5.6 times the radius of the Sun. The orbital plane is inclined by an angle of 90° to the line of sight, causing the secondary component to be completely eclipsed once per orbit. [5] The orbital period shows long-term cyclic variations, changing by up to 0.0051 days every 17.32 years. This may be due to magnetic activity cycles or the influence of a third body. The orbital period as a whole is steadily decreasing at the rate of (−5.39±0.03)×10−7 days yr−1 due to loss of mass and angular momentum by the system. [4]
The physical properties of the stellar components can be explained by a mass transfer. At some point in the past, mass flowed from the (at the time) more massive and evolved secondary component. This has left the primary as an A-type main-sequence star while the secondary is less massive but overly large. The hotter primary component is a Delta Scuti variable that is undergoing radial pulsation with a dominant frequency of 21.852 days−1 and a secondary frequency of 23.484 days−1. [5]
