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A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".
61 Cygni is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. Of apparent magnitude 5.20 and 6.05, respectively, they can be seen with binoculars in city skies or with the naked eye in rural areas without light pollution.
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young stellar objects as its immediate products. It is closely related to planet formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a single star, must also account for the statistics of binary stars and the initial mass function. Most stars do not form in isolation but as part of a group of stars referred as star clusters or stellar associations.
36 Ophiuchi is a triple star system 19.5 light-years from Earth. It is in the constellation Ophiuchus.
Messier 67 and sometimes called the King Cobra cluster or the Golden Eye cluster is an open cluster in the southern, equatorial half of Cancer. It was discovered by Johann Gottfried Koehler in 1779. Estimates of its age range between 3.2 and 5 billion years. Distance estimates are likewise varied, but typically are 800–900 parsecs (2,600–2,900 ly). Estimates of 855, 840, and 815 pc were established via binary star modelling and infrared color-magnitude diagram fitting.
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71 Tauri is a suspected triple star system in the zodiac constellation Taurus, located 146 light years from the Sun. It is visible to the naked eye as a faint, yellow-white hued star with an apparent visual magnitude of +4.48. The star is moving further away from the Earth with a heliocentric radial velocity of +38 km/s. It is a member of the Hyades open cluster.
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In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space.
The Hertzsprung–Russell diagram, abbreviated as H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures. The diagram was created independently in 1911 by Ejnar Hertzsprung and by Henry Norris Russell in 1913, and represented a major step towards an understanding of stellar evolution.
HD 28527 is a star in the constellation Taurus, and a member of the Hyades open cluster. It is faintly visible to the naked eye with an apparent visual magnitude of 4.78. The distance to this star, as determined from its parallax shift of 22 mas, is 148 light years. It is moving away from the Earth with a heliocentric radial velocity of +38 km/s.
56 Cygni is a single star in the northern constellation of Cygnus, located 135 light years from Earth. It is visible to the naked eye as a white-hued star with an apparent visual magnitude of 5.06. The star is moving closer to the Earth with a heliocentric radial velocity of −21.5. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.181″/yr. According to Eggen (1998), this is a member of the Hyades Supercluster.
ζ Fornacis is the Bayer designation for a star in the southern constellation of Fornax. It is faintly visible to the naked eye with an apparent visual magnitude of 5.67. Based upon a measured annual parallax shift of 29.9 mas, it is located at a distance of about 109 light-years from the Sun. The star is drifting further away with a radial velocity of +29 km/s. Positioned about 1.3° to the southeast of Zeta Fornacis is the galaxy NGC 1232.
V957 Scorpii is a variable star in the constellation of Scorpius. It is a blue straggler in the open cluster Messier 7, a star that is unexpectedly hot compared to other members of the cluster.
79 Tauri, also known as b Tauri, is an Am star in the constellation of Taurus with an apparent magnitude of 5.0. It is a member of the Hyades open cluster and parallax measurements by Gaia give a distance of about 157 light years.
References
- ↑ Barnes, Sydney (March 2003). "On the rotational evolution of Solar- and Late-Type Stars, Its Magnetic Origins, and the Possibility of Stellar Gyrochronology". The Astrophysical Journal. 586 (1): 464–479. arXiv: astro-ph/0303631 . Bibcode:2003ApJ...586..464B. doi:10.1086/367639.
- ↑ Barnes, Sydney (November 2007). "Ages for Illustrative Field Stars Using Gyrochronology: Viability, Limitations, and Errors". The Astrophysical Journal. 669 (2): 1167–1189. arXiv: 0704.3068 . Bibcode:2007ApJ...669.1167B. doi:10.1086/519295.
- ↑ Skumanich, Andrew (February 1972). "Time Scales for CA II Emission Decay, Rotational Braking, and Lithium Depletion". The Astrophysical Journal. 171: 565. Bibcode:1972ApJ...171..565S. doi:10.1086/151310.
- ↑ Radick, Richard; Thompson, D. T.; Lockwood, G. W.; Duncan, D. K.; Baggett, W. E. (October 1987). "The activity, variability, and rotation of lower main-sequence Hyades stars". The Astrophysical Journal. 321: 459–472. Bibcode:1987ApJ...321..459R. doi:10.1086/165645.
- ↑ Meibom, Søren; Barnes, Sydney A.; Platais, Imants; Gilliland, Ronald L.; Latham, David W.; Mathieu, Robert D. (5 January 2015). "A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster". Nature. 517: 589–591. arXiv: 1501.05651 . Bibcode:2015Natur.517..589M. doi:10.1038/nature14118. PMID 25539085.