Dobson, Amy (2016) Kinematics and age spreads of the young star-forming region NGC 2264. Doctoral thesis, Keele University.

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While stars are relatively well understood, the timescales on which they form are still debated. The young cluster NGC 2264 is an ideal region in which to test hypotheses about the timescale of star and cluster formation. Co-eval stars at any given effective temperature are expected to have similar luminosities and radii, but previous research on clusters, including NGC 2264, has found that this may not be the case. In this thesis, fibre spectroscopy from the FLAMES spectrograph is used to find radial and projected equatorial velocities for many low-mass pre-main sequence stars in NGC 2264. Projected radii are estimated by combining these data with published rotation periods. The projected radius distribution is compared with models incorporating radius and age dispersions. These methods circumvent many uncertainties that arise when using luminosities to infer ages from the Hertzsprung-Russell diagram (HRD). Comparisons of models and data favour a spread of radii that is inconsistent with a coeval population but consistent with the spread of ages seen in the HRD. Model-dependent, but distance-independent, ages of 1 - 2.6 Myrs are found, and agreement with ages determined from the HRD is found for a cluster distance of 770± 46 pc. The cluster velocity dispersion is well resolved, and a connection between spatial and kinematic substructure is established. The substructure is unlikely to be responsible for the observed age dispersion. A catalogue of 547 spectroscopic observations of stars in NGC 2264 is presented, with measurements of radial and projected equatorial velocities.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QB Astronomy
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Contributors: Jeffries, RD (Thesis advisor)
Depositing User: Lisa Bailey
Date Deposited: 03 Nov 2016 10:13
Last Modified: 11 Aug 2022 09:26

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