Astronomy:T Draconis
280px T Draconis in optical light | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Draco[1] |
| Right ascension | 17h 56m 23.32885s[2] |
| Declination | +58° 13′ 06.7834″[2] |
| Apparent magnitude (V) | 7.2–13.5[3] |
| Characteristics | |
| Spectral type | C6,2e-C8,3e(N0e)[3] |
| B−V color index | 2.70[1] |
| Variable type | Mira[3] |
| Astrometry | |
| Radial velocity (Rv) | −23±2[4] km/s |
| Proper motion (μ) | RA: −2.849[2] mas/yr Dec.: +22.260[2] mas/yr |
| Parallax (π) | 1.0214 ± 0.0786[2] mas |
| Distance | 3,200 ± 200 ly (980 ± 80 pc) |
| Details | |
| Radius | 670[5] R☉ |
| Luminosity | 6,900 (min); 13,300 (max)[5] L☉ |
| Temperature | 2,400[5] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
T Draconis (abbreviated T Dra) is a carbon-rich Mira variable star located in the constellation Draco.
The star's carbon-rich atmosphere produces a spectrum dominated by carbon-bearing molecular features. Its red appearance is caused by its cool, carbon rich atmosphere.
Location and identification
T Draconis is located in the northern circumpolar constellation of Draco, positioned at the celestial coordinates of right ascension 17h 56m 23.3s and declination +58° 13′ 06.8″ (J2000 epoch).[2] Based on parallax measurements from the Gaia space observatory, the star is situated approximately 3,200 light-years (980 parsecs) away from Earth.[2]
As a long-period Mira variable, the star's apparent magnitude fluctuates dramatically over a period of roughly 422 days. At its peak brightness (maximum magnitude ~7.2), it can be resolved using standard binoculars under dark skies. At its faintest (minimum magnitude ~13.5), it dims significantly, requiring a moderate-to-large aperture amateur telescope to detect.[3]
T Draconis is readily identified through visual astronomy by its intense, ruby-red or charred-orange coloration. This extreme index is a hallmark of highly evolved carbon stars, whose outer atmospheres are rich in carbon molecules (such as C2 and CN) that heavily absorb short-wavelength blue light. In the eyepiece, it forms a prominent visual double with UY Draconis—an 11th-magnitude white-yellow star.
References
- ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A XHIP record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 "T Dra". AAVSO. https://vsx.aavso.org/index.php?view=detail.top&oid=13675.
- ↑ 4.0 4.1 "V* T Dra". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+T+Dra.
- ↑ 5.0 5.1 5.2 Tatarnikov, A. M.; Zheltoukhov, S. G. et al. (January 2024). "Study of the Carbon Star T Draconis" (in en). Astronomy Letters 50 (1): 53–61. doi:10.1134/S1063773724600176. ISSN 1063-7737. Bibcode: 2024AstL...50...53T.
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