All Outputs (6)

A lithium depletion boundary age of 21 Myr for the Beta Pictoris moving group (2013)
Journal Article
Binks, A. S., & Jeffries, R. D. (2014). A lithium depletion boundary age of 21 Myr for the Beta Pictoris moving group. Monthly Notices of the Royal Astronomical Society: Letters, 438(1), L11-L15. https://doi.org/10.1093/mnrasl/slt141

Optical spectroscopy is used to confirm membership for eight low-mass candidates in the young Beta Pic moving group (BPMG) via their radial velocities, chromospheric activity and kinematic parallaxes. We searched for the presence of the Li I 6708 Å r... Read More about A lithium depletion boundary age of 21 Myr for the Beta Pictoris moving group.

A lithium depletion boundary age of 22 Myr for NGC 1960 (2013)
Journal Article
Jeffries, R. D., Naylor, T., Mayne, N. J., Bell, C. P. M., & Littlefair, S. P. (2013). A lithium depletion boundary age of 22 Myr for NGC 1960. Monthly Notices of the Royal Astronomical Society, 434(3), 2438-2450. https://doi.org/10.1093/mnras/stt1180

We present a deep Cousins RI photometric survey of the open cluster NGC 1960, complete to RC ≃ 22, IC ≃ 21, that is used to select a sample of very low mass cluster candidates. Gemini spectroscopy of a subset of these is used to confirm membership an... Read More about A lithium depletion boundary age of 22 Myr for NGC 1960.

No evidence for intense, cold accretion on to YSOs from measurements of Li in T-Tauri stars (2013)
Journal Article
Sergison, D. J., Mayne, N. J., Naylor, T., Jeffries, R. D., & Bell, C. P. M. (2013). No evidence for intense, cold accretion on to YSOs from measurements of Li in T-Tauri stars. Monthly Notices of the Royal Astronomical Society, 434(2), 966-977. https://doi.org/10.1093/mnras/stt973

We have used medium-resolution spectra to search for evidence that proto-stellar objects accrete at high rates during their early ‘assembly phase’. Models predict that depleted lithium and reduced luminosity in T-Tauri stars are key signatures of ‘co... Read More about No evidence for intense, cold accretion on to YSOs from measurements of Li in T-Tauri stars.

Pre-main-sequence isochrones – II. Revising star and planet formation time-scales (2013)
Journal Article
Bell, C. P. M., Naylor, T., Mayne, N. J., Jeffries, R. D., & Littlefair, S. P. (2013). Pre-main-sequence isochrones – II. Revising star and planet formation time-scales. Monthly Notices of the Royal Astronomical Society, 434(1), 806-831. https://doi.org/10.1093/mnras/stt1075

We have derived ages for 13 young (<30 Myr) star-forming regions and find that they are up to a factor of 2 older than the ages typically adopted in the literature. This result has wide-ranging implications, including that circumstellar discs survive...

On the relationship between the size and surface coverage of starspots on magnetically active low-mass stars (2013)
Journal Article
Jackson, R. J., & Jeffries, R. D. (2013). On the relationship between the size and surface coverage of starspots on magnetically active low-mass stars. Monthly Notices of the Royal Astronomical Society, 431(2), 1883-1890. https://doi.org/10.1093/mnras/stt304

We present a model that predicts the light curve amplitude distribution for an ensemble of low-mass magnetically active stars, under the assumptions that stellar spin axes are randomly orientated and that cool starspots have a characteristic scale le... Read More about On the relationship between the size and surface coverage of starspots on magnetically active low-mass stars.

Angular momentum evolution of cool stars: Toward a synthesis of observations and theory before and after the ZAMS (2013)
Journal Article
Meibom, S., Barnes, S., Covey, K., Jeffries, R., Matt, S., Morin, J., Palacios, A., Reiners, A., Sicilia-Aguilar, A., & Irwin, J. (2013). Angular momentum evolution of cool stars: Toward a synthesis of observations and theory before and after the ZAMS. Astronomische Nachrichten, 334(1-2), 168-171. https://doi.org/10.1002/asna.201211777

The coexistence of fast and slowly rotating cool stars in ZAMS clusters – forming distinct sequences in the color vs. rotation period plane – is providing clues to differences in their pre main-sequence angular momentum evolution. This Cool Stars 17... Read More about Angular momentum evolution of cool stars: Toward a synthesis of observations and theory before and after the ZAMS.