Keid
|
Triple star Keid (40 Eri) |
||
|---|---|---|
| Observation data epoch : J2000.0 |
||
| AladinLite | ||
| Constellation | Eridanus | |
| Astrometry | ||
| distance | 16.45 ± 0.07 ly (5.04 ± 0.02 pc ) |
|
| period | A: BC 8,000 years B: C 252 years |
|
| Age | 4 to 12 billion years | |
| Individual data | ||
| Names | A , B , C | |
| Observation data: | ||
| Right ascension | A. | 4 h 15 m 16.3201 s |
| B. | 4 h 15 m 21.786 s | |
| C. | 4 h 15 m 21.733 s | |
| declination | A. | −7 ° 39 ′ 10,336 ″ |
| B. | −7 ° 39 ′ 29.22 ″ | |
| C. | −7 ° 39 ′ 17.36 ″ | |
|
Apparent brightness |
A. | 4.43 m |
| B. | 9.52 m | |
| C. | 11.19 m | |
| Typing: | ||
| Spectral class | A. | K0.5 V |
| B. | DA4 | |
| C. | M4.5 Ve | |
| BV color index | A. | +0.82 |
| B. | +0.03 | |
| C. | +1.67 | |
| UB color index | A. | +0.45 |
| B. | −0.68 | |
| C. | +0.83 | |
| Astrometry: | ||
|
Absolute visual brightness M vis |
A. | 5.92 likes |
| B. | 11.01 mag | |
| C. | 12.68 mag | |
| Physical Properties: | ||
| Dimensions | A. | 0.75 M ☉ |
| B. | 0.5 M ☉ | |
| C. | 0.13 M ☉ | |
| radius | A. | 0.87 R ☉ |
| B. | 0.016 R ☉ | |
| C. | 0.22 R ☉ | |
| Luminosity | A. | 0.365 L ☉ |
| B. | 0.00336 L ☉ | |
| C. | 0.000722 L ☉ | |
| Effective temperature | A. | 5,165 K |
| B. | 12,600 K | |
| C. | 3,370 K | |
| Rotation time | A. | 20.8 d |
| B. | 0.5 d | |
| C. | 4 d | |
| Designations and catalog entries | ||
| Bayer-Bez. | ο 2 Eri | |
| Flamsteed-Bez. | 40 Eri | |
| Bonn diam. | BD -7 ° 781 | |
| Bright Star Cat. | HR 1325 | |
| Hipparcos catalog | HIP 19849 | |
| ADS catalog | ADS 3093 | |
| Other names |
DY Eri, GJ 166, LHS 23 / LHS 24 / LHS 25 |
|
| HD catalog | A. | HD 26965 |
| B. | HD 26976 | |
| C. | HD 26976 | |
| SAO catalog | A. | SAO 131063 |
| B. | SAO 131065 | |
| C. | SAO 131065 | |
40 Eridani , also as ο 2 Eridani ( Omicron 2 Eridani ) or Keid (from the Arabic wordالقيض, DMG al-qaiḍ 'egg shell') is a triple star system less than 16.5 light years from Earth .
The system lies in the constellation Eridanus and was identified as a binary star system by William Herschel in 1783 . In 1851 Otto Wilhelm von Struve discovered that one of the components is itself a binary star system. In 1910, component B was identified as a white dwarf because this star belongs to spectral type A despite its low luminosity . This star was the first compact dwarf star to be discovered.
General
40 Eridani A is an orange main sequence star of the fourth magnitude of the spectral class K1. It has about 25% less mass than the sun and about a third of its luminosity. Like his two companions, he is between four and twelve billion years old.
40 Eridani B , a ninth size white dwarf (spectral class DA4), has about half the mass of the sun. Since it has already left the main sequence phase behind, it can be assumed that this star was the most massive component when the system was formed. After leaving the main series to eventually become the white dwarf, it shed much of its original mass.
40 Eridani C is a red dwarf eleventh size with the spectral class M4.5 Ve and belongs to the flare stars . As a changeable one he is called DY Eridani.
The components B and C orbit the primary star in about 400 AU within about 8000 years. The close pair B and C move in an orbit with a radius of about 35 AU, with one orbit taking about 252 years.
Planetary system
In 2018, a planet in the orbit of 40 Eridani A was discovered in the habitable zone with a minimum mass of 8.47 ± 0.47 earth masses and thus classified as super-earth .
| planet |
Orbital time [d] |
Major semi-axis [AE] |
Inclination [degree] |
Radius [R E ] |
Dimensions |
|---|---|---|---|---|---|
| b | 42.38 ± 0.01 days | 0.22446 ± 0.00004 | - | - | 8.47 ± 0.47 M E |
40 Eridani in fiction
In the fictional Star Trek universe, 40 Eridani A is the sun of Spock's homeworld Vulkan . Although this was never directly mentioned in film and television, both the licensed book Star Trek: Star Charts and Star Trek inventor Gene Roddenberry himself refer to 40 Eridani as the star orbiting the volcano. In addition, Commander Tucker , one of the main characters of the TV series Star Trek: Enterprise , speaks of a distance of 16 light years between volcano and earth, which corresponds approximately to the actual distance of 40 Eridani.
Web links
Individual evidence
- ^ MAC Perryman et al .: The Hipparcos Catalog .
- ↑ Bo Ma, Jian Ge, Matthew Muterspaugh, Michael A Singer, Gregory W Henry, Jonay I González Hernández, Sirinrat Sithajan, Sarik Jeram, Michael Williamson, Keivan Stassun, Benjamin Kimock, Frank Varosi, Sidney Schofield, Jian Liu, Scott Powell, Anthony Cassette, Hali Jakeman, Louis Avner, Nolan Grieves, Rory Barnes, Sankalp Gilda, Jim Grantham, Greg Stafford, David Savage, Steve Bland, Brent Ealey: The first super-Earth Detection from the High Cadence and High Radial Velocity Precision Dharma Planet Survey . In: Monthly Notices of the Royal Astronomical Society . 480, No. 2, 2018, p. 2411. arxiv : 1807.07098 . bibcode : 2018MNRAS.480.2411M . doi : 10.1093 / mnras / sty1933 .
- ↑ Super-Earth in the constellation Eridanus: Is this the home planet of Mr. Spock? In: Spiegel Online . September 19, 2018, accessed October 7, 2018 .
- ↑ https://detektor.fm/wissen/heimatplanet-von-mr-spock-entdeck
- ↑ Vulcan's sun . projectrho.com In: Sky & Telescope magazine , July 1991.