DI Herculis
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Double star DI Herculis |
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| AladinLite | |||||||||||||||||
| Constellation | Hercules | ||||||||||||||||
| Right ascension | 18 h 53 m 26.2 s | ||||||||||||||||
| declination | + 24 ° 16 ′ 40.8 ″ | ||||||||||||||||
| Apparent brightness | 8.47 likes | ||||||||||||||||
| Astrometry | |||||||||||||||||
| distance | approx. 2000 ly | ||||||||||||||||
| orbit | |||||||||||||||||
| period | 10.55 days | ||||||||||||||||
| Individual data | |||||||||||||||||
| Names | A; B. | ||||||||||||||||
| Typing: | |||||||||||||||||
| Spectral class | A. | B5 V | |||||||||||||||
| B. | B4 V | ||||||||||||||||
| Other names and catalog entries |
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DI Herculis is a binary star system of Algol-type in the constellation Hercules . The system has an apparent magnitude of about +8.5 mag, consists of two young blue stars of the spectral classes B5 and B4 and is about 2000 light years away.
The orbit of the stars around the common center of gravity is strongly elliptical with an eccentricity of 0.2. Together with a semiaxis a of 0.496 astronomical units and stellar masses of 4.52 and 5.15 solar masses, a theoretical apse rotation of 4.27 ° per 100 years is expected. This value is made up of a relativistic proportion of 2.34 ° per 100 years and a classic proportion of 1.93 ° per 100 years. In contrast, the observed value is only 1.04 ° per 100 years.
This deviation in the bright double star has triggered intensive studies over the past 30 years. The following solutions were discussed:
- New theories on gravitation (see also Modified Newtonian Dynamics )
- fast circularization of the elliptical orbit
- Change in the rotation of the vestibule by a third body in the orbit system
- Presence of a circumstellar cloud between the components of the binary star system with a gravitational influence
- Position of the axes of rotation of the stars
Using the Rossiter-McLaughlin effect , it was possible in 2009 to prove that the axes of rotation of the two B stars are approximately in the orbit plane of the binary star system . If this is included in the calculations of the vestibule rotation , the deviation between the expected and measured value disappears within the scope of the measurement inaccuracy. With that, DI Herculis can no longer be regarded as an indication of a possible falsification of the general theory of relativity .
Web links
- DI Herculis - An unusually eccentric algol system ; Astronomical News, volume 265, p.101, 1938, bibcode : 1938AN .... 265..101L
- Precession of the binary star DI Herculis and binary pulsar PSR J1518 + 4904
literature
- S. Albrecht, S. Reffert, I. Snellen: Misaligned spin and orbital axes cause the anomalous precession of DI Herculis . In: Nature . tape 461 , 2009, p. 373–376 , doi : 10.1038 / nature08408 .
- K. Hsnan, R. Mardling: A Three Body Solution for the DI Her System . In: Astrophysics and Space Science . tape 304 , 2006, p. 243-246 , doi : 10.1007 / s10509-006-9121-0 .
- A. Claret, G. Torres, M. Wolf: DI Herculis as a test of internal stellar structure and general relativity . In: Astronomy & Astrophysics . tape 515 , 2010, doi : 10.1051 / 0004-6361 / 200913942 .
- A. Dariush, N. Riazi: A New Apsidal Motion Study of DI Her . In: Astrophysics and Space Science . tape 283 , 2003, p. 253-261 , doi : 10.1023 / A: 1021380815734 .
- SA Khodykon: Evidence for a third body in the eclipsing binary DI Herculis . In: International Bulletin of Variable Stars . tape 5788 , 2007.
Individual evidence
- ^ Hipparcos catalog (1997), bibcode : 1997A & A ... 323L..49P
- ↑ Einstein's nemesis: DI Herculis
- ↑ DI Her
- ↑ UBVR photometry of DI Herculis