V766 Centauri

Database links to V766 Centauri

Double star V766 Centauri
artistic conception of V766 Centauri
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	centaur
Right ascension	13 h 47 m 10.87 s
declination	-62 ° 35 ′ 23 ″
Apparent brightness	6.8 (6.11-7.50) mag
Typing
B − V color index	+1.98
U − B color index	+1.19
Spectral class	K0 0-Ia / B0 Ibp
Variable star type	irregular
Astrometry
Radial velocity	−38.20 km / s
parallax	(1.35 ± 1.95)  mas
distance	11,700  ly 3,600  pc
Proper movement
Rec. Share:	−2.94  mas / a
Dec. portion:	−2.54  mas / a
Physical Properties
Dimensions	39  M ☉
radius	1315  R ☉
Luminosity	~ 500,000-1,000,000  L ☉
Effective temperature	5000  K
Rotation time	10-30 d
Other names and catalog entries
Cordoba Survey CD −61 ° 3988 Bright Star Catalog HR 5171 [1] Henry Draper Catalog HD 119796 [2] Hipparcos catalog HIP 67261 [3] SAO catalog SAO 252448 [4] Other names V766 Centauri

V766 Centauri , also known as HR 5171 or HD 119796 , is a multiple star system in the constellation Centaur and about 3,600 parsecs from Earth . The spectral type of the primary star (component Aa) fluctuates between G8Ia + and K3Ia + and its brightness fluctuates irregularly, partly because it is an eclipsing star: it has a very close, somewhat hotter companion (component Ab). Both stars are so close that they touch. Another star (component B) orbits the system.

development

The component Aa of V766 Centauri had an initial mass of 40 solar masses and is developing into a red hypergiant. This star sheds its remaining shells in huge explosions, with its temperature increasing more and more. In the further course it would evolve into a blue supergiant or luminous blue variable , but will probably explode in a supernova beforehand due to the loss of its shell to its partner (component Ab) . Another possible scenario would be for him to keep part of his shell and thereby remain stable with his companion.

Physical Properties

The system was examined by the European Southern Observatory with the Very Large Telescope Interferometer (VLTI). The observations revealed that V766 Centauri Aa the largest known yellow star and he to 1,300 times the diameter of the sun has. It is part of a binary star system, where its partner is so close that they touch (English: contact binaries). They rotate in 1300  days . If placed in the place of the sun, this star would extend beyond Jupiter's orbit . The volume of V766 Centauri Aa is about 2.274 billion times that of the Sun. It is 50 percent larger than the red supergiant Betelgeuse and 1 million times brighter than the sun. The close companion Ab is also a bright yellow giant star, with a radius of about a third of the primary star, with a similar surface temperature. However, it only contributes to a small part of the total luminosity (about 12%) and probably only has a tenth of the mass of V766 Centauri Aa. This information comes from model calculations, since the data from the two stars cannot be sufficiently separated from one another.

It was also found that V766 Centauri Aa grows over time and that it is one of the few stars that change their temperature and size at the same time: as it grows, it cools down at the same time.

The astronomers also found out that the star is not just a double, but a multiple star system . The second companion star, V766 Centauri B, orbits the two close companions (Aa and Ab) in a comparatively wide orbit, at a distance of at least 35,000 AU.

The hot distant companion V766 Centauri B is a blue supergiant of type B0, 316,000 times as bright as our sun. Although this is almost half of the bolometric luminosity of the primary star, its optical brightness is only three magnitudes lower, since a large part of its radiation is emitted in the non-visible UV range.

The high luminosity , huge size and mass transfer with its smaller companion make V766 Centauri Aa a very rare type of star that has not yet been studied very intensively.

Web links

Commons : V766 Centauri  - Collection of images, videos and audio files

• ESO: The VLT spots the largest yellow hypergiant (+ photos, map & animation) March 12, 2014
• ESO: VLTI re-examines the largest known yellow hypergiant

Individual evidence

1. ↑ ^{a b c d e} HD 119796. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed September 10, 2018 . 
2. ↑ V0766 Cen. In: VSX. AAVSO, accessed September 10, 2018 . 
3. ↑ ^{a b} http://www.wissenschaft.de/erde-weltall/astronomie/-/journal_content/56/12054/3134458/Kosmischer-Riese/
4. ↑ ^{a b} O. Chesneau, A. Meilland, E. Chapellier, F. Millour, AM Van Genderen, Y. Nazé, N. Smith, A. Spang, JV Smoker, L. Dessart, S. Kanaan, Ph. Bendjoya, MW Feast, JH Groh, A. Lobel, N. Nardetto, S. Otero, RD Oudmaijer, AG Tekola, PA Whitelock, C. Arcos, M. Curé, L. Vanzi: The yellow hypergiant HR 5171 A: Resolving a massive interacting binary in the common envelope phase . In: Astronomy & Astrophysics . 563, 2014, p. A71. arxiv : 1401.2628v2 . bibcode : 2014A & A ... 563A..71C . doi : 10.1051 / 0004-6361 / 201322421 .
5. ↑ AM Van Genderen, H. Nieuwenhuijzen, A. Lobel: An early detection of blue luminescence by neutral PAHs in the direction of the yellow hypergiant HR 5171A? . In: Astronomy & Astrophysics . 583, 2015, p. A98. arxiv : 1509.07421 . bibcode : 2015A & A ... 583A..98V . doi : 10.1051 / 0004-6361 / 201526392 .