66 Eridani

Star in the constellation Eridanus

66 Eridani  Observation data
Epoch J2000 Equinox J2000

Constellation | Eridanus
Right ascension | 05h 06m 45.65314s[1]
Declination | −04° 39′ 18.5939″[1]
Apparent magnitude (V) | 5.12[2]
Characteristics
Spectral type | B9V[3]
U−B color index | -0.16[4]
B−V color index | -0.06[4]
Variable type | α2 CVn
Astrometry
Radial velocity (Rv)| 32.28 ± 0.10[5] km/s
Proper motion (μ)|  RA: 10.70[1] mas/yr
Dec.: -0.78[1] mas/yr
Parallax (π)| 10.56 ± 0.34 mas[1]
Distance| 309 ± 10 ly
(95 ± 3 pc)
Absolute magnitude (MV)| 0.37[6]
Orbit[5]
Period (P)| 5.5226013 ± 0.0000020 d
Eccentricity (e)| 0.0844 ± 0.0013
Periastron epoch (T)| 2441356.499 ± 0.017
Argument of periastron (ω)
(secondary)| 160.9 ± 1.1°
Semi-amplitude (K1)
(primary)| 102.83 ± 0.20 km/s
Semi-amplitude (K2)
(secondary)| 100.35 ± 0.19 km/s
Details[5]
66 Eri A
Mass| 2.629 ± 0.032 M☉
Radius| 1.948 ± 0.063 R☉
Luminosity| 51.3 ± 3.3 L☉
Surface gravity (log g)| 4.28 ± 0.03 cgs
Temperature| 11077 K
Rotational velocity (v sin i)| 17.1 ± 0.2 km/s
Age| 30 Myr
66 Eri B
Mass| 2.566 ± 0.032 M☉
Radius| 1.919 ± 0.061 R☉
Luminosity| 46.9 ± 3.0 L☉
Surface gravity (log g)| 4.28 ± 0.03 cgs
Temperature| 10914 K
Rotational velocity (v sin i)| 16.9 ± 0.2 km/s
Other designations

EN Eri, BD−04° 1044, HD 32964, HIP 23794, HR 1657, SAO 131777[7]

Database references
SIMBAD| data

66 Eridani is a binary star in the constellation of Eridanus. The combined apparent magnitude of the system is 5.12 on average.[2] Parallax measurements by Hipparcos put the system at some 309 light-years (95 parsecs) away.[1]

This is a spectroscopic binary: the two stars cannot be individually resolved, but periodic Doppler shifts in its spectrum mean there must be orbital motion. The two stars orbit each other every 5.5226013 days.[5] Their orbit is fairly eccentric, at 0.0844.[5]

The combined spectrum of 66 Eridani matches that of a B-type main-sequence star,[3] and the two stars have similar masses.[5] The spectrum also shows excess of mercury and manganese, as it is a type of chemically peculiar star called a mercury-manganese star.[5] 66 Eridani is an Alpha2 Canum Venaticorum variable. For this reason, it has been given the designation EN Eridani.[7]

## References[edit]

1. ^ a b c d e f van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
2. ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
3. ^ a b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5: 0. Bibcode:1999MSS...C05....0H.
4. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
5. ^ a b c d e f g Makaganiuk, V.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. (2011). "Chemical spots in the absence of magnetic field in the binary Hg Mn star 66 Eridani". Astronomy & Astrophysics. 529: A160. arXiv:1102.4661. Bibcode:2011A&A...529A.160M. doi:10.1051/0004-6361/201016302. S2CID 118419097.
6. ^ Hubrig, S.; et al. (June 2001), "Search for low-mass PMS companions around X-ray selected late B stars", Astronomy and Astrophysics, 372: 152–164, arXiv:astro-ph/0103201, Bibcode:2001A&A...372..152H, doi:10.1051/0004-6361:20010452, S2CID 17507782.
7. ^ a b "* 66 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 August 2017.

* v
* t
* e

Constellation of Eridanus

* List of stars in Eridanus
* Eridanus in Chinese astronomy

Stars|

| Bayer|

* α (Achernar)
* β (Cursa)
* γ (Zaurak)
* δ
* ε (Ran)
* ζ (Zibal)
* η (Azha)
* θ1 (Acamar)
* θ2
* ι
* κ
* λ
* μ
* ν
* ξ
* ο1 (Beid)
* ο2 (Keid) (40)
* π
* ρ1
* ρ2
* ρ3
* τ1
* τ2 (Angetenar)
* τ3
* τ4
* τ5
* τ6
* τ7
* τ8
* τ9
* υ1
* υ2 (Theemin)
* υ3 (Beemim)
* υ4
* φ
* χ
* ψ
* ω
* p

|

Flamsteed|

* 14
* 15
* 17 (v)
* 39 (A)
* 45
* 51 (c)
* 53 (Sceptrum)
* 54
* 58
* 64
* 66

Variable|

* EF
* EP
* KT

HR|

* 506 (q1)
* 789 (s)
* 1106 (y)
* 1143 (h)
* 1189 (f)
* 1190 (f)
* 1195 (g)
* 1483
* 1536
* 1614

HD|

* 28185
* 30562
* 30963

Other|

* 82 G. (e)
* DENIS 0255−4700
* Gliese 86
* GJ 180
* GJ 1062
* Gliese 3293
* HIP 12961 (Koeia)
* Gliese 3323
* LTT 1445
* LP 890-9
* 2MASS J04151954−0935066
* WASP-35
* WASP-50 (Chaophraya)
* WASP-78

| Exoplanets|

* 51 Eridani b
* Epsilon Eridani b (Ægir)
* Gliese 86 b
* HD 10647 b (q1 Eridani b)
* HD 19467 B
* HD 28185 b
* HD 30562 b
* WASP-79b (Pollera)

|

| Nebulae|

* NGC 1535

|

Galaxies|

| NGC|

* 782
* 852
* 939
* 1084
* 1132
* 1140
* 1172
* 1187
* 1189
* 1190
* 1191
* 1192
* 1199
* 1222
* 1232
* 1234
* 1241
* 1262
* 1266
* 1269
* 1291
* 1300
* 1309
* 1325
* 1332
* 1337
* 1345
* 1347
* 1353
* 1357
* 1369
* 1386
* 1395
* 1400
* 1403
* 1404
* 1407
* 1426
* 1427A
* 1436
* 1437
* 1439
* 1452
* 1460
* 1487
* 1531
* 1532
* 1592
* 1600
* 1614
* 1637
* 1721
* 1723
* 1725
* 1728
* 1741

|

Other|

* Eridanus II
* ESO 198-13
* IC 1953
* IC 2006
* LEDA 74886

| Galaxy clusters|

* Abell 383
* Eridanus Cluster
* Eridanus Group
* MACS J0416.1-2403

|

| Astronomical events|

* GRB 080913

|

Category
*[RA:]: Right Ascension
*[Dec.:]: Declination
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