NGC 3766 (also known as Caldwell 97) is an open star cluster in the southern constellation Centaurus. It is located in the vast star-forming region known as the Carina molecular cloud, and was discovered by Nicolas Louis de Lacaille during his astrometric survey in 1751–1752. At a distance of about 1745 pc,[2] the cluster subtends a diameter of about 12 minutes of arc.[3]
Open cluster in the constellation Centaurus
NGC 3766
NGC 3766 image taken with the MPG/ESO 1.2-metre telescope at the La Silla Observatory[1] Credit: ESO
Observation data (J2000 epoch)
Constellation
Centaurus
Right ascension
11h36.1m
Declination
−61° 37′
Distance
5.5 kly
Apparent magnitude (V)
5.3
Apparent dimensions (V)
12.0′
Physical characteristics
Radius
9.6 ly
Notable features
Easy to view via binoculars or telescope
Other designations
Pearl Cluster[citation needed], NGC 3766, Caldwell 97, Collinder 248, Melotte 107, Dunlop 289, Lacaille III.7, C1133-613
There are 137 listed stars, but many are likely non-members, with only 36 having accurate photometric data.[4] It has a total apparent magnitude of 5.3 and integrated spectral type of B1.7.[2] NGC 3766 is relatively young, with an estimated age of log (7.160) or 14.4 million years,[3] and is approaching us at 14.8km/s.[2] This cluster contains eleven Be stars, two red supergiants and four Ap stars.[4]
36 examples of an unusual type of variable star were discovered in the cluster. These fast-rotating pulsating B-type stars vary by only a few hundredths of a magnitude with periods less than half a day. They are main sequence stars, hotter than δ Scuti variables and cooler than slowly pulsating B stars.[5]
Saio, H; Ekström, S; Mowlavi, N; Georgy, C; Saesen, S; Eggenberger, P; Semaan, T; Salmon, S. J. A. J (2017). "Period–luminosity relations of fast-rotating B-type stars in the young open cluster NGC 3766". Monthly Notices of the Royal Astronomical Society. 467 (4): 3864. arXiv:1702.02306. Bibcode:2017MNRAS.467.3864S. doi:10.1093/mnras/stx346.
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