NGC 4815

NGC 4815 is an open cluster in the constellation Musca. It was discovered by John Herschel in 1834. It is located approximately 10,000 light years away from Earth.

NGC 4815
Observation data (J2000 epoch)
ConstellationMusca
Right ascension12h 58m 01s[1]
Declination−64° 57′ 36″[1]
Distance10,040 ly (3,079 pc[2])
Apparent magnitude (V)8.6 [1]
Apparent dimensions (V)7'[3]
Physical characteristics
Mass880 ±230[4] M☉
Estimated age400 million years[3]
Other designationsCr 265, VDBH 142

Characteristics

NGC 4815 is an intermediate age cluster. Carraro and Ortolani determined the age of the cluster to be 500 million years, based on BV photometry, which is nearly the same as the Hyades,[5] while Sagar et al. determined its age at 400±50 million years[6] and Kharchenko et al. at 400 million years.[3] Friel at al. estimated its age to be between 500 and 630 million years.[7]

There are 69 probable member stars within the angular radius of the cluster and 39 within the central part of the cluster.[3] Five blue stragglers have been detected in the cluster,[8] and 15 red giants are probable members of the cluster.[6] The earliest main sequence stars are of type A0. One of the stars in the cluster region shows extremely red colour along with blue ultraviolet colour and it could be an interacting binary star.[6] The turnoff point is at 2.6 ±0.1 M☉.[7]

The members show small dispersions in abundance, with the exception of Mg, which is common for clusters of rather low mass, as NGC 4815.[7] The mean metallicity of the cluster is [Fe/H] = +0.03 ± 0.05 dex (as estimated by Frieal et al.)[7] or −0.01 ± 0.04 (as estimated by Tautvaišienė et al.).[9] Alpha-elements [Ca/Fe] and [Si/Fe] show solar ratios, [Mg/Fe] is moderately enhanced, [Ti/Fe] is slightly subsolar, [Al/Fe] is enhanced, and [Na/Fe] is significantly enhanced.[7] THE CNO abundances in the cluster are [C/H] = −0.17 ± 0.08, [N/H] = 0.53 ± 0.07, [O/H] = 0.12 ± 0.09, and [C/N] = 0.79 ± 0.08.[9]

References
  1. "NGC 4815". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-19.
  2. WEBDA page for open cluster NGC 4815
  3. Kharchenko, N. V.; Piskunov, A. E.; Schilbach, E.; Röser, S.; Scholz, R.-D. (3 October 2013). "Global survey of star clusters in the Milky Way". Astronomy & Astrophysics. 558: A53. arXiv:1308.5822. Bibcode:2013A&A...558A..53K. doi:10.1051/0004-6361/201322302.
  4. Prisinzano, L.; Carraro, G.; Piotto, G.; Seleznev, A. F.; Stetson, P. B.; Saviane, I. (15 April 2001). "Luminosity and mass function of galactic open clusters I. NGC 4815". Astronomy & Astrophysics. 369 (3): 851–861. arXiv:astro-ph/0101371. Bibcode:2001A&A...369..851P. doi:10.1051/0004-6361:20010202.
  5. Carraro, G.; Ortolani, S. (September 1994). "Deep CCD BV photometry of the poorly studied open cluster NGC 4815". Astronomy and Astrophysics Supplement. 106: 573–579. Bibcode:1994A&AS..106..573C.
  6. Sagar, Ram; Munari, U.; de Boer, K.S. (October 2001). "A multicolour CCD photometric and mass function study of the distant southern open star clusters NGC 3105, NGC 3603, Melotte 105, Hogg 15, NGC 4815, Pismis 20 and NGC 6253". Monthly Notices of the Royal Astronomical Society. 327 (1): 23–45. Bibcode:2001MNRAS.327...23S. doi:10.1046/j.1365-8711.2001.04438.x.
  7. Friel, E. D.; Donati, P.; Bragaglia, A.; Jacobson, H. R.; Magrini, L.; Prisinzano, L.; Randich, S.; Tosi, M.; Cantat-Gaudin, T.; Vallenari, A.; Smiljanic, R.; Carraro, G.; Sordo, R.; Maiorca, E.; Tautvaišien*error*ė, G.; Sestito, P.; Zaggia, S.; Jiménez-Esteban, F. M.; Gilmore, G.; Jeffries, R. D.; Alfaro, E.; Bensby, T.; Koposov, S. E.; Korn, A. J.; Pancino, E.; Recio-Blanco, A.; Franciosini, E.; Hill, V.; Jackson, R. J.; de Laverny, P.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.; Hourihane, A.; Costado, M. T.; Jofré, P.; Lind, K. (19 March 2014). "Gaia -ESO Survey: Properties of the intermediate age open cluster NGC 4815". Astronomy & Astrophysics. 563: A117. arXiv:1403.7451. Bibcode:2014A&A...563A.117F. doi:10.1051/0004-6361/201323215.
  8. Ahumada, J. A.; Lapasset, E. (20 November 2006). "New catalogue of blue stragglers in open clusters". Astronomy & Astrophysics. 463 (2): 789–797. Bibcode:2007A&A...463..789A. doi:10.1051/0004-6361:20054590.
  9. Tautvaišienė, G.; Drazdauskas, A.; Mikolaitis, Š.; Barisevičius, G.; Puzeras, E.; Stonkut*error*ė, E.; Chorniy, Y.; Magrini, L.; Romano, D.; Smiljanic, R.; Bragaglia, A.; Carraro, G.; Friel, E.; Morel, T.; Pancino, E.; Donati, P.; Jiménez-Esteban, F.; Gilmore, G.; Randich, S.; Jeffries, R. D.; Vallenari, A.; Bensby, T.; Flaccomio, E.; Recio-Blanco, A.; Costado, M. T.; Hill, V.; Jofré, P.; Lardo, C.; de Laverny, P.; Masseron, T.; Moribelli, L.; Sousa, S. G.; Zaggia, S. (17 December 2014). "The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705". Astronomy & Astrophysics. 573: A55. arXiv:1411.2831. Bibcode:2015A&A...573A..55T. doi:10.1051/0004-6361/201424989.


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