R Coronae Australis
File:R Coronae Australis region.jpg A colour photo of the R Coronae Australis region in the southern Milky Way. | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | +11.91 |
| Characteristics | |
| Spectral type | B5IIIpe[2] |
| Variable type | INSA[3] |
| Astrometry | |
| Radial velocity (Rv) | Script error: No such module "val".[4] km/s |
| Proper motion (μ) | RA: 1.582[5] mas/yr Dec.: −30.835[5] mas/yr |
| Parallax (π) | 10.5361±0.6971 mas[5] |
| Distance | Script error: No such module "val".[6] pc |
| Absolute magnitude (MV) | −0.30[7] |
| Orbit | |
| Period (P) | Script error: No such module "val".[8] yr |
| Semi-major axis (a) | Script error: No such module "val".[8]" (27-28 AU[6]) |
| Eccentricity (e) | 0.4[6] |
| Inclination (i) | 70[6]° |
| Details | |
| A | |
| Mass | 3.5[7] Template:Solar mass |
| Radius | 6.2[7] Template:Solar radius |
| Luminosity | 132[7] Template:Solar luminosity |
| Temperature | 9,550[7] K |
| Age | Script error: No such module "val".[6] Myr |
| B | |
| Mass | 0.3 - 0.55[6] Template:Solar mass |
| Surface gravity (log g) | Script error: No such module "val".[6] cgs |
| Temperature | 3,650 - 3,870[6] K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| CD−37°13027, HIP 93449, Wray 15-1887 | |
| Database references | |
| SIMBAD | data |
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R Coronae Australis (R CrA) is a variable binary system in the constellation Corona Australis.[2][8] It has varied between magnitudes 10 and 14.36.[10] A small reflection/emission nebula NGC 6729 extends from the star towards SE. It is also the brightest feature of the Coronet Cluster, therefore sometimes called R CrA Cluster.
This star is moving toward the Solar System with a radial velocity of 36 km s−1. It was previously believed that in roughly 222,000 years, this system could have approached within Script error: No such module "convert". of the Sun. However, the estimate had a considerable margin of error in it.[11] With the release of Gaia DR2, the star was determined to be 4 times further from the Sun than initially believed, constraining the approach to only Script error: No such module "convert"..[5] Examination of other objects known to be in the same star-forming region gives a distance of Script error: No such module "val"., suggesting an error in the Gaia parallax for R CrA itself.[6]
Johann Friedrich Julius Schmidt discovered that R Coronae Australis is a variable star, in 1865. It appeared with its variable star designation in Annie Jump Cannon's 1907 work Second Catalogue of Variable Stars.[12]
A companion to the star was proposed in 2019 with a mass between 0.1 and 1 Solar masses, depending on the characteristics of the stellar environment, orbiting the primary in 43–47 years.[8] The companion was later directly observed to be a red dwarf with a mass between Template:Solar mass and Template:Solar mass.[6] It has also been proposed that the primary component is itself a close binary.[7]
References
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