BY Dragon - a multiple star system in the constellation Dragon . It consists of at least three components. Components A and B form a close binary system with a circulation period of 5.98 days. These stars have not yet entered the main sequence and are in the process of formation. They belong to the spectral types dK5e and dK7e, respectively. Dragon BY is a prototype of variable stars like Dragon BY .
| BY Dragon AB | |||
|---|---|---|---|
| Star | |||
| Observational data ( Age J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Distance | 53.6 ± 0.6 St. years (16.4 ± 0.2 pc ) | ||
| Visible magnitude ( V ) | + 8.07 | ||
| Constellation | The Dragon | ||
| Astrometry | |||
| Radial velocity ( R v ) | −27 ± 5 km / s | ||
| Own movement (μ) | RA: 186.62 mas per year Dec: −324.90 mas per year | ||
| Parallax (π) | 60.90 ± 0.73 mas | ||
| Absolute magnitude (V) | +7.10 | ||
| Specifications | |||
| Spectral class | K6Ve | ||
| Color Index ( B - V ) | 1.19 | ||
| Color Index ( U - B ) | 0.99 | ||
| Variability | BY Dra | ||
| physical characteristics | |||
| Temperature | |||
| |||
| Database Information | |||
| SIMBAD | data | ||
The third component (C) is a distance of 260 a from the pair AB . e. Component C is a red dwarf of spectral type M5. It is possible that the fourth component is present in the system with a circulation period of 114 days, but so far its existence has not been visually confirmed [3] .
Studying a star, one can imagine how the young Sun looked like, at the dawn of its evolution, before nuclear reactions started in it. On Dragon BY there are giant spots or their groups covering about a quarter of the visible surface of the star. On the modern Sun, spots occupy only thousandths of the area of its disk. BY Dragon rotates around its axis seven times faster than our luminary (turnover in 4 days) and due to spots periodically flares up and dims. The total area of the spots slowly fluctuates over time, changing the brightness of the star by 30 percent with a cycle of 50 ≈ 60 years. If the Sun behaved in the same way, the whole Earth would turn into Antarctica , then into Sahara .
Most researchers believe [4] that the main component (A) contributes most to variability, while component B gives only a third of the total luminosity, however, giant spots can also be on it.
Notes
- ↑ 1 2 3 4 Gaia Data Release 2 - 2018.
- ↑ 1 2 Activity and the Li abundances in the FGK dwarfs // Astron. Astrophys. - EDP Sciences , 2012. - ISSN 0004-6361 ; 0365-0138 ; 1432-0746 ; 1286-4846 - doi: 10.1051 / 0004-6361 / 201118412
- ↑ Boden, AF; Lane, BF A Preliminary Visual Orbit of BY Draconis (Eng.) // The Astrophysical Journal . - IOP Publishing , 2001. - Vol. 547 , no. 2 . - P. 1071-1076 . - DOI : 10.1086 / 318394 .
- ↑ Pettersen, BR; Olah, K .; Sandmann, WH Longterm behavior of starspots. II - A decade of new starspot photometry of BY Draconis and EV Lacertae (Eng.) // Astronomy and Astrophysics Supplement Series : journal. - EDP Sciences 1992. - Vol. 96 , no. 3 . - P. 497-504 .