Delta Ophiuchi
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Star δ Ophiuchi |
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Snake bearer | ||||||||||||||||||||
| Right ascension | 16 h 14 m 20.7 s | ||||||||||||||||||||
| declination | -03 ° 41 ′ 40 ″ | ||||||||||||||||||||
| Apparent brightness | 2.73 mag | ||||||||||||||||||||
| Typing | |||||||||||||||||||||
| B − V color index | +1.58 | ||||||||||||||||||||
| U − B color index | +1.96 | ||||||||||||||||||||
| R − I index | +1.03 | ||||||||||||||||||||
| Spectral class | M1 III | ||||||||||||||||||||
| Variable star type | Yes | ||||||||||||||||||||
| Astrometry | |||||||||||||||||||||
| Radial velocity | (−19.6 ± 0.1) km / s | ||||||||||||||||||||
| parallax | (19.06 ± 0.16) mas | ||||||||||||||||||||
| distance | (171 ± 1) ly (52.5 ± 0.4) pc |
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| Visual absolute brightness M vis | −0.87 mag | ||||||||||||||||||||
| Proper movement | |||||||||||||||||||||
| Rec. Share: | (−47.54 ± 0.22) mas / a | ||||||||||||||||||||
| Dec. portion: | (−142.73 ± 0.14) mas / a | ||||||||||||||||||||
| Physical Properties | |||||||||||||||||||||
| Dimensions | (1.6 ± 0.3) M ☉ | ||||||||||||||||||||
| radius | (56) R ☉ | ||||||||||||||||||||
| Luminosity |
(500) L ☉ |
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| Effective temperature | (3800) K | ||||||||||||||||||||
| Metallicity [Fe / H] | (0.32) | ||||||||||||||||||||
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Other names and catalog entries |
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Delta Ophiuchi ( δ Ophiuchi , also abbreviated Delta Oph , δ Oph ) is a star of the spectral class M1 in the constellation of the Serpent Bearer . It has an apparent magnitude of 2.73 mag. This corresponds to a third magnitude star. This makes it the fourth brightest star in this constellation. According to measurements of the parallax by Hipparcos , the star is about 170 light years away from Earth. He bears the proper name Yed Prior (Arabic يد jad / Latin), "front hand". It forms a visual double star with Epsilon Ophiuchi (proper name: Yed Posterior , distance approx. 106 light years) , visible to the naked eye .
nomenclature
δ Ophiuchi is the Bayer designation for the star.
The traditional name of this star is Yed Prior . Yed is derived from the Arabic word "Yad" and means "the hand". Delta and Epsilon Ophiuchi together form the left hand of Ophiuchus (beating bearer), which holds the head of a snake. This head is called "Serpens Caput" and is a constellation of stars in the constellation Snake . As of October 5, 2016, the name "Yed Prior" has been the standard name of this star, included in the list of star names of the International Astronomical Union .
properties
Delta Ophiuchi belongs to the spectral class M 1 III. The star is a red giant star. It has almost used up its hydrogen supply for nuclear fusion. As a result, its outer sheaths have expanded significantly. The apparent diameter of the star could be observed to be 10.47 ± 0.12 mas. The distance determined by Hipparchus results in a sun diameter of about 59 times. Despite its large diameter compared to the sun, the star only has 1.5 times the mass of the sun.
The effective temperature of the photosphere of the star is relatively cool with approx. 3700 K. For this reason the star glows in the orange-red light, which is typical for a class M star.
The star belongs to the class of variable stars . Its brightness fluctuates visually by 0.03 size classes. The star's equatorial rotation speed is 7.0 km / s. The presence of elements that are heavier than hydrogen and helium ( metallicity ) is twice as high as in our sun.
The light emitted by the star is increasingly linearly polarized from red to blue frequencies and shows a certain variability. This property can indicate an asymmetrical distribution of dust in its outer shell. It is also conceivable that a photometric hotspot is responsible for this.
Events
δ Ophiuchi was late in the evening ( GMT ) of July 8, 2010 by nearly 11 likes darker asteroids (472) Roma for about 5 seconds covered . This event could be observed from Europe and South America . Because of the great brightness of δ Ophiuchi, this event was theoretically visible to the naked eye.
Individual evidence
- ↑ a b c Hipparcos catalog (ESA 1997)
- ↑ a b c Bright Star Catalog
- ↑ Pulkovo radial velocities for 35493 HIP stars
- ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
- ↑ a b T Tsuji: Cool luminous stars: The hybrid nature of their infrared spectra . In: Astronomy & Astrophysics . 489, No. 3, 2008, p. 1271. arxiv : 0807.4387 . bibcode : 2008A & A ... 489.1271T . doi : 10.1051 / 0004-6361: 200809869 .
- ↑ a b P Cruzalèbes, A Jorissen, Y Rabbia, S Sacuto, A Chiavassa, E Pasquato, B Plez, K Eriksson, A Spang, O Chesneau: Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI / AMBER . In: Monthly Notices of the Royal Astronomical Society . 434, 2013, p. 437. arxiv : 1306.3288 . bibcode : 2013MNRAS.434..437C . doi : 10.1093 / mnras / stt1037 .
- ↑ a b Naming Stars . IAU.org. Retrieved June 28, 2018.
- ↑ mas = milli-arcseconds