| luminosity=50[13]
| temperature=4,900[13]
| metal_fe=-0.28[15]
| rotational_velocity=8[16]
| age_gyr=1[13]
}}{{Starbox catalog
| names= η Her, 44 Her, HR 6220, BD -39° 3029, HD 150997, FK5 626, HIP 81833, SAO 65504, GC 22502, CCDM J16428+3855A
}}{{Starbox reference
|Simbad=HD+150997}}{{Starbox end}}{{Sky|16|42|53.80|+|38|55|20.116|1000000}}Eta Herculis (η Her, η Herculis) is a fourth-magnitude star in the constellation Hercules.
Properties
Eta Herculis is a G-Type star. With a stellar classification G7.5IIIb, it is yet considerably larger having a mass that is 2.3 times solar and a radius 9.8 times.[13] Though it only shines with an apparent magnitude of 3.48, it is part of the "Keystone" asterism, visible overhead in the mid-summer night sky to northern observers, allowing it to be easily recognized. Eta Herculis is 50 times more luminous than the Sun.[13] The Hipparcos satellite mission estimated its distance at roughly 34.4 parsecs[9] from Earth, or 112 light years away.
If one follows the line connecting Eta Herculis with Zeta Herculis one comes across one of the earliest and most stunning globular clusters in the nighttime sky, M13, discovered in 1714 by Edmond Halley.
Eta Herculis is a double star once thought to be part of a binary star system.[13]
See also
- Lists of stars in the constellation Hercules
- Class G Stars
- Double star
References
1. ^1 2 3 4 5 6 {{cite web | title=ETA HER (Eta Herculis) | publisher=University of Illinois | work=Stars | first1=James B. | last1=Kaler | url=http://stars.astro.illinois.edu/sow/etaher.html | accessdate=2010-06-09 }}
2. ^1 2 {{cite journal | author=Perryman, M. A. C. | author2=Lindegren, L. | author3=Kovalevsky, J. | author4=Hoeg, E. | display-authors=etal | title=The HIPPARCOS Catalogue | journal=Astronomy and Astrophysics | date=July 1997 | volume=323 | pages=L49–L52 | bibcode=1997A&A...323L..49P }}
3. ^1 {{cite journal |author1=Soubiran, C. |author2=Bienaymé, O. |author3=Mishenina, T. V. |author4=Kovtyukh, V. V. | title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants | journal=Astronomy and Astrophysics | date=2008 | volume=480 | issue=1 | pages=91–101 | url=http://cds.aanda.org/index.php?option=article&access=bibcode&bibcode=2008A%2526A...480...91S | bibcode=2008A&A...480...91S | doi=10.1051/0004-6361:20078788 |arxiv = 0712.1370 }}
4. ^1 {{cite journal | author=Mermilliod, J.-C. | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished) | journal=Catalogue of Eggen's UBV data | date=1986 | bibcode=1986EgUBV........0M }}
5. ^1 2 3 4 5 6 7 {{cite simbad | title=* eta Her | accessdate = 2010-06-09 }}
6. ^1 {{cite journal |author1=Bernacca, P. L. |author2=Perinotto, M. | title=A catalogue of stellar rotational velocities. | journal=Contributi Osservatorio Astronomico di Padova in Asiago | date=1970 | volume= 239 | bibcode=1970CoAsi.239....1B}}
7. ^1 2 {{citation | last1=Pizzolato | first1=N. | last2=Maggio | first2=A. | last3=Sciortino | first3=S. | title=Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases | journal=Astronomy and Astrophysics | volume=361 | pages=614–628 |date=September 2000 | bibcode=2000A&A...361..614P }}