# Nu Hydrae

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Nu_Hydrae
> Markdown URL: https://mediated.wiki/source/Nu_Hydrae.md
> Source: https://en.wikipedia.org/wiki/Nu_Hydrae
> Source revision: 1345161472
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Star in the constellation Hydra

Nu Hydrae Location of ν Hydrae (circled) Observation data Epoch J2000 Equinox J2000 Constellation Hydra[1] Right ascension 10h 49m 37.48875s[2] Declination −16° 11′ 37.1360″[2] Apparent magnitude (V) 3.115[3] Characteristics Spectral type K0/K1 III[4] U−B color index +1.305[3] B−V color index +1.239[3] Astrometry Radial velocity (Rv) −1.37±0.25[5] km/s Proper motion (μ) RA: +93.35[2] mas/yr Dec.: +198.88[2] mas/yr Parallax (π) 23.7940±0.1695 mas[6] Distance 137.1 ± 1.0 ly (42.0 ± 0.3 pc) Absolute magnitude (MV) −0.11[1] Details Mass 2.0[7] M☉ Radius 21[5] R☉ Luminosity 151[5] L☉ Surface gravity (log g) 2.3[5] cgs Temperature 4,335[5] K Metallicity [Fe/H] −0.30[5] dex Rotational velocity (v sin i) 5.3[5] km/s Other designations ν Hya, 4 Crateris, BD−15 3138, FK5 410, HD 93813, HIP 52943, HR 4232, SAO 156256[8] Database references SIMBAD data

**Nu Hydrae**, [Latinized](/source/Romanization_of_Greek) from ν Hydrae, is an orange-hued [star](/source/Star) in the [constellation](/source/Constellation) [Hydra](/source/Hydra_(constellation)), near the border with the neighboring constellation of [Crater](/source/Crater_(constellation)). It has an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 3.115,[3] which is bright enough to be seen with the naked eye. Based upon [parallax](/source/Parallax) measurements, this star is located at a distance of about 137 [light-years](/source/Light-year) (42 [parsecs](/source/Parsec)) from the [Earth](/source/Earth).[2]

The [spectrum](/source/Stellar_spectrum) of this star matches a [stellar classification](/source/Stellar_classification) of K0/K1 III,[4] where the [luminosity class](/source/Luminosity_class) of 'III' indicates this is a [giant star](/source/Giant_star) that has exhausted the supply of hydrogen at its core and [evolved](/source/Stellar_evolution) away from the [main sequence](/source/Main_sequence). The radius of this star has expanded to 21 times the [Sun's radius](/source/Solar_radius)[5] and it radiates about 151 times the [luminosity of the Sun](/source/Solar_luminosity).[5] This expanded outer envelope has an [effective temperature](/source/Effective_temperature) of about 4,335 K,[5] giving it the characteristic orange hue of a K-type star.[9]

Nu Hydrae is an X-ray emitter with an estimated luminosity of 6.6 × 1028 [erg](/source/Erg) s−1 in the X-ray band.[7] The abundance of elements other than hydrogen and helium, what astronomers term the star's [metallicity](/source/Metallicity),[5] is about half that in the Sun.[a] It has a relatively high [proper motion](/source/Proper_motion) across the [celestial sphere](/source/Celestial_sphere),[8] suggesting that it has a [peculiar velocity](/source/Peculiar_velocity) roughly three times higher than its neighbors.[10]

Nu Hydrae was a later designation of **4 Crateris**.[11]

## Notes

1. **[^](#cite_ref-metal_10-0)** The actual abundance of metals relative to the abundance in the Sun can be derived by taking the metallicity estimate to the power of ten, thus: 1. 10[Fe/H] = 10−0.30 ≈ 0.50

## References

1. ^ [***a***](#cite_ref-Anderson2012_1-0) [***b***](#cite_ref-Anderson2012_1-1) Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", *[Astronomy Letters](/source/Astronomy_Letters)*, **38** (5): 331, [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971), [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A), [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015). [XHIP record for this object](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-ref=VIZ681510a8389ecb&-out.src=V%2F137D%2FXHIP&-nav=cat%3AV%2F137D%26tab%3A{V%2F137D%2FXHIP}%26key%3Asource%3DV%2F137D%2FXHIP%26HTTPPRM%3A&-source=V%2F137D%2FXHIP&-out=HIP&HIP=52943&-out=Comp&-out=Gr&-out=RAJ2000&-out=DEJ2000&-out=Dist&-out=X&-out=Y&-out=Z&-out=SpType&-out=Simbad&-out=Hpmag&-out=Lum&-out=Cst) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-aaa474_2_653_2-0) [***b***](#cite_ref-aaa474_2_653_2-1) [***c***](#cite_ref-aaa474_2_653_2-2) [***d***](#cite_ref-aaa474_2_653_2-3) [***e***](#cite_ref-aaa474_2_653_2-4) van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", *Astronomy and Astrophysics*, **474** (2): 653–664, [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357), [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600)

1. ^ [***a***](#cite_ref-sps1966_3-0) [***b***](#cite_ref-sps1966_3-1) [***c***](#cite_ref-sps1966_3-2) [***d***](#cite_ref-sps1966_3-3) Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", *Publications of the Department of Astronomy University of Chile*, **1**, Publicaciones Universidad de Chile, Department de Astronomy: 1–17, [Bibcode](/source/Bibcode_(identifier)):[1966PDAUC...1....1G](https://ui.adsabs.harvard.edu/abs/1966PDAUC...1....1G)

1. ^ [***a***](#cite_ref-aaa339_858_4-0) [***b***](#cite_ref-aaa339_858_4-1) di Benedetto, G. P. (November 1998), "Towards a fundamental calibration of stellar parameters of A, F, G, K dwarfs and giants", *Astronomy and Astrophysics*, **339**: 858–871, [Bibcode](/source/Bibcode_(identifier)):[1998A&A...339..858D](https://ui.adsabs.harvard.edu/abs/1998A&A...339..858D)

1. ^ [***a***](#cite_ref-aj135_1_209_5-0) [***b***](#cite_ref-aj135_1_209_5-1) [***c***](#cite_ref-aj135_1_209_5-2) [***d***](#cite_ref-aj135_1_209_5-3) [***e***](#cite_ref-aj135_1_209_5-4) [***f***](#cite_ref-aj135_1_209_5-5) [***g***](#cite_ref-aj135_1_209_5-6) [***h***](#cite_ref-aj135_1_209_5-7) [***i***](#cite_ref-aj135_1_209_5-8) [***j***](#cite_ref-aj135_1_209_5-9) [***k***](#cite_ref-aj135_1_209_5-10) Massarotti, Alessandro; et al. (January 2008). ["Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity"](https://doi.org/10.1088%2F0004-6256%2F135%2F1%2F209). *The Astronomical Journal*. **135** (1): 209–231. [Bibcode](/source/Bibcode_(identifier)):[2008AJ....135..209M](https://ui.adsabs.harvard.edu/abs/2008AJ....135..209M). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/135/1/209](https://doi.org/10.1088%2F0004-6256%2F135%2F1%2F209).

1. **[^](#cite_ref-Gaia3_6-0)** [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. (Gaia collaboration) (2021). ["*Gaia* Early Data Release 3: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202039657). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **649**: A1. [arXiv](/source/ArXiv_(identifier)):[2012.01533](https://arxiv.org/abs/2012.01533). [Bibcode](/source/Bibcode_(identifier)):[2021A&A...649A...1G](https://ui.adsabs.harvard.edu/abs/2021A&A...649A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202039657](https://doi.org/10.1051%2F0004-6361%2F202039657). [S2CID](/source/S2CID_(identifier)) [227254300](https://api.semanticscholar.org/CorpusID:227254300). (Erratum: [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202039657e](https://doi.org/10.1051%2F0004-6361%2F202039657e)). [Gaia EDR3 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20EDR3%203557567320183657472) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-aaa352_217_7-0) [***b***](#cite_ref-aaa352_217_7-1) Gondoin, P. (December 1999), "Evolution of X-ray activity and rotation on G-K giants", *Astronomy and Astrophysics*, **352**: 217–227, [Bibcode](/source/Bibcode_(identifier)):[1999A&A...352..217G](https://ui.adsabs.harvard.edu/abs/1999A&A...352..217G)

1. ^ [***a***](#cite_ref-SIMBAD_8-0) [***b***](#cite_ref-SIMBAD_8-1) ["LTT 3973 -- High proper-motion Star"](http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+93813), *SIMBAD*, [Centre de Données astronomiques de Strasbourg](/source/Centre_de_Donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2012-01-13

1. **[^](#cite_ref-csiro_9-0)** ["The Colour of Stars"](https://web.archive.org/web/20131203222826/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html), *Australia Telescope, Outreach and Education*, [Commonwealth Scientific and Industrial Research Organisation](/source/Commonwealth_Scientific_and_Industrial_Research_Organisation), December 21, 2004, archived from [the original](http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html) on December 3, 2013, retrieved 2012-01-16

1. **[^](#cite_ref-kaler_11-0)** Kaler, James B., ["Nu Hydrae"](http://stars.astro.illinois.edu/sow/nuhya.html), *Stars*, University of Illinois, retrieved 2012-01-13

1. **[^](#cite_ref-12)** Wagman, M. (August 1987). "Flamsteed's Missing Stars". *Journal for the History of Astronomy*. **18** (3): 215. [Bibcode](/source/Bibcode_(identifier)):[1987JHA....18..209W](https://ui.adsabs.harvard.edu/abs/1987JHA....18..209W). [doi](/source/Doi_(identifier)):[10.1177/002182868701800305](https://doi.org/10.1177%2F002182868701800305). [S2CID](/source/S2CID_(identifier)) [118445625](https://api.semanticscholar.org/CorpusID:118445625).

v t e Constellation of Hydra List of stars in Hydra Hydra in Chinese astronomy Stars Bayer α (Alphard) β γ (Naga) δ ε (Ashlesha) ζ η θ ι (Ukdah) κ λ μ ν ξ ο π ρ σ (Minchir) τ1 τ2 υ1 (Zhang) υ2 φ1 φ2 φ3 χ1 χ2 ψ ω b1 b3 C F Flamsteed 1 2 3 6 (a) 9 10 12 (D) 14 15 17 19 20 21 23 24 25 26 27 (P) 28 29 33 (A) 34 37 44 47 48 50 51 (k) 52 (l) 54 (m) 55 56 57 58 (Solitaire) 59 60 10 Crt 17 Crt 20 Crt 2 Sex Variable R U V W TW EX HS KU LQ V361 V419 V421 V478 V484 HR 3378 3538 3749 (G) 3750 3858 (I) 3862 3919 3923 (Felis) 4162 4328 4339 (β Ant) 4445 5265 HD 72659 74156 82943 86226 86264 90156 (γ Ant) Other 2MASS 1114−2618 ESO 439-26 Gliese 328 Gliese 357 Gliese 433 Gliese 453 GJ 3634 HAT-P-30 HE 1256−2738 HE 1327−2326 LHS 2065 LHS 3003 LTT 3780 SDSS J090745.0+024507 WASP-25 WASP-36 WASP-84 WASP-166 (Filetdor) WISE 0855−0714 WISEA J1141−3326 Exoplanets Gliese 357 d HD 72659 b HD 74156 b c HD 82943 b c HD 86226 b HD 86264 b TW Hydrae b (unconfirmed) WASP-193b Star clusters Messier 48 Messier 68 NGC 5694 Price-Whelan 1 Nebulae Abell 33 Abell 35 NGC 3242 Southern Owl Nebula Galaxies Messier 83 NGC 2617 2642 2697 2708 2758 2835 2848 2865 2890 2935 2936 2937 2960 2962 2986 2992 3030 3052 3054 3081 3109 3124 3200 3285 3285B 3290 3305 3307 3308 3309 3311 3312 3313 3314 3315 3316 3336 3369 3383 3393 3402 3463 3464 3585 3621 3673 3717 3904 3923 3936 4980 4993 5042 5061 5078 5085 5101 5135 5260 5264 5495 5626 Other 3C 196.1 AM 1316−241 Arp 7 CTQ 327 ESO 510-G13 GAMA202627 GLEAM J0917−0012 Hydra A IC 535 MRC 1138−262 Peekaboo Galaxy PKS 1151−348 RX J0911.4+0551 SDSS J0841+0101 TN J0924−2201 Tololo 1247−232 ZwCl 1693 BCG Galaxy clusters Abell 754 Abell 3411 Abell 3412 Bullet Group Hickson 40 Astronomical events GW170817 Category

---
Adapted from the Wikipedia article [Nu Hydrae](https://en.wikipedia.org/wiki/Nu_Hydrae) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Nu_Hydrae?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.