| 词条 | NGC 3228 |
| 释义 |
| name = NGC 3228 | image = File:NGC 3228 map.png | caption = Location of NGC 3228 | credit = | type = Open Cluster | epoch = J2000 | constellation = Vela | ra = {{RA|10|21|22}}[1] | dec = {{DEC|-51|43|42}}[1] | dist_ly = 1,870 ly | dist_pc = 573 pc[2] | appmag_v = 6.0 [1] | size_v =11'[2] | mass_msol = | age = 260 million years[2] | notes = | names = Collinder 218, vdBH 93 }}NGC 3228 is an open cluster in Vela. It was discovered by Nicolas Louis de Lacaille in 1751–1752, while he was in South Africa and catalogued it as Lac II.7.[3] It is small but bright and can be observed easily with binoculars in sufficiently dark skies.[4] It is a cluster of Trumpler type I1p or II3p, with few members with large brightness range and a slight concentration toward its center.[3] Klarchenko et al. mention 53 possible members within the angular diametre of the cluster. The tidal radius of the cluster is 1.4 – 5.5 parsecs (4.5 – 18 light years) and represents the average outer limit of NGC 3228, beyond which a star is unlikely to remain gravitationally bound to the cluster core.[2] The brightest member is of mag. 7.9 and the hottest star is of spectral type B9.[3] One member, HD 89856 (mag. 9.04, spectral type B9), is a variable star with period 4.556 days.[5] References1. ^1 2 {{cite simbad| title=NGC 3228| accessdate=2015-06-19}} 2. ^1 2 3 {{cite journal|last1=Kharchenko|first1=N. V.|last2=Piskunov|first2=A. E.|last3=Schilbach|first3=E.|last4=Röser|first4=S.|last5=Scholz|first5=R.-D.|title=Global survey of star clusters in the Milky Way|journal=Astronomy & Astrophysics|date=3 October 2013|volume=558|pages=A53|doi=10.1051/0004-6361/201322302|url=ftp://cdsarc.u-strasbg.fr/pub/cats/J/A%2BA/558/A53/catalog.dat|arxiv = 1308.5822 |bibcode = 2013A&A...558A..53K }} 3. ^1 2 {{cite web|last1=Kronberg|first1=Christine|last2=Frommert|first2=Hartmut|title=NGC 3228|url=http://messier.seds.org/xtra/ngc/n3228.html|website=messier.seds.org}} 4. ^{{cite book|last1=Monks|first1=Neale|title=Go-To Telescopes Under Suburban Skies|date=2010|publisher=Springer Science & Business Media|isbn=9781441968517|url=https://books.google.gr/books?id=waO6tUtfblsC&pg=PA40|page=40|language=en}} 5. ^{{cite journal|last1=Paunzen|first1=E.|last2=Hensberge|first2=H.|last3=Maitzen|first3=H. M.|last4=Netopil|first4=M.|last5=Trigilio|first5=C.|last6=Fossati|first6=L.|last7=Heiter|first7=U.|last8=Pranka|first8=M.|title=A photometric long-term study of chemically peculiar stars in open clusters|journal=Astronomy & Astrophysics|date=26 November 2010|volume=525|pages=A16|doi=10.1051/0004-6361/200913789|url=ftp://cdsarc.u-strasbg.fr/pub/cats/J/A%2BA/525/A16/stars.v00|arxiv = 1012.0149 |bibcode = 2011A&A...525A..16P }} External links{{wikiSky}}{{Ngc35}} 3 : NGC objects|Vela (constellation)|Open clusters |
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