BD Camelopardalis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Camelopardalis |
| Right ascension | 03h 42m 09.325s |
| Declination | +63° 13′ 00.501″ |
| Apparent magnitude (V) | 5.115 |
| Characteristics | |
| Spectral type | S3.5/2 (M4III) |
| U−B color index | 1.82 |
| B−V color index | 1.63 |
| R−I color index | 1.39 |
| Variable type | Symbiotic star V* BD Cam |
| Astrometry | |
| Radial velocity (Rv) | -22.0 km/s |
| Proper motion (μ) | RA: -16.97 mas/yr Dec.: 19.34 mas/yr |
| Parallax (π) | 6.27 ± 0.63 mas |
| Distance | approx. 520 ly (approx. 160 pc) |
| Absolute magnitude (MV) | -0.90 |
| Details | |
| Red giant primary | |
| Radius | 135 R☉ |
| Luminosity | 185(v)/1600(bol) L☉ |
| Surface gravity (log g) | 0.9 cgs |
| Temperature | 3250 K |
| Metallicity | 0.0 |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
BD Camelopardalis is an S star and symbiotic star in the constellation Camelopardalis. It was recognized as a spectroscopic binary star in 1922, and its orbital solution published in 1984;[1] it has a 596-day orbital period. A spectroscopic composition analysis was done of the red giant primary star in 1986.[2]
Description
Although the star's spectrum shows the spectral features of zirconium oxide which define spectral class S, BD Cam shows no technetium lines in its spectrum. It is believed to be an "extrinsic" S star, one whose s-process element excesses originate in a binary companion star. The system displays only minimal variations in the visible, but the presence of the companion and its interactions with the stellar wind of the visible red giant makes for easily observed time-variable spectral features in the ultraviolet and in the near infrared spectral line of helium.
At times BD Cam is the brightest S star in the visible sky, because other bright S stars are mira variables or other types of variable star with large changes in apparent brightness. Its own brightness variability in the visible part of the spectrum is modest.
On the basis of the measurement of radial velocities of the line components it is concluded that the helium emission originates in the vicinity of the inner Lagrangian point of the system, indicating a gas motion from the red giant primary, directed to the secondary, with a velocity of about 5 km/s. At the same time, there is a high-velocity, hot wind outwards from the primary red giant with a velocity of about 50 km/s.— Shcherbakov, A. G. and Tuominen, I.
However, HR 1105 appears to have a highly variable UV companion. In 1982, no UV flux was discerned for this system, but by 1986 C IV was strong, increasing by a factor of 3 in 1987 with prominent lines of Si III, C III, O III, Si IV, and N V.— Ake, Thomas B., III; Johnson, Hollis R. and Perry, Benjamin F., Jr.
References
- ↑ Griffin, R.F. (1984). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 58: HR 1105". Observatory 104: 224–231. Bibcode:1984Obs...104..224G.
- ↑ Smith, V.V.; Lambert, D.L. (1986). "The chemical composition of red giants. II - Helium burning and the s-process in the MS and S stars". Astrophysical Journal 311: 843–863. Bibcode:1986ApJ...311..843S. doi:10.1086/164823.
- Shcherbakov, A. G.; Tuominen, I.; Tuominen (1992). "Activity modulation of the red giant HR 1105 as observed in the He I lambda 10830 A". Astronomy & Astrophysics 255: 215–220. Bibcode:1992A&A...255..215S.
- Ake, Thomas B., III; Johnson, Hollis R.; Perry, Benjamin F., Jr.; Johnson; Perry (1988). "Companions to peculiar red giants: HR 363 and HR 1105". In ESA, A Decade of UV Astronomy with the IUE Satellite 1: 245–248. Bibcode:1988uvai....1..245A.
- HR 1105
- Image BD Camelopardalis
- Symbiotic Star Blows Bubbles Into Space
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