All Outputs (26)

A WISE-based search for debris discs amongst M-dwarfs in nearby, young, moving groups (2017)
Journal Article
Binks, A. S., & Jeffries, R. (2017). A WISE-based search for debris discs amongst M-dwarfs in nearby, young, moving groups. Monthly Notices of the Royal Astronomical Society, 496(1), 579-593. https://doi.org/10.1093/mnras/stx838

We present a search for debris discs amongst M-dwarf members of nearby, young (5–150 Myr) moving groups (MGs) using infrared (IR) photometry, primarily from the Wide Infrared Survey Explorer (WISE). A catalogue of 100 MG M dwarfs that have suitable W... Read More about A WISE-based search for debris discs amongst M-dwarfs in nearby, young, moving groups.

The Gaia-ESO Survey: the inner disk, intermediate-age open cluster Trumpler 23 (2017)
Journal Article
Jeffries. (2017). The Gaia-ESO Survey: the inner disk, intermediate-age open cluster Trumpler 23. Astronomy and Astrophysics, https://doi.org/10.1051/0004-6361/201629345

Context. Trumpler 23 is a moderately populated, intermediate-age open cluster within the solar circle at a RGC ~ 6 kpc. It is in a crowded field very close to the Galactic plane and the color–magnitude diagram shows significant field contamination an... Read More about The Gaia-ESO Survey: the inner disk, intermediate-age open cluster Trumpler 23.

The Gaia-ESO Survey: revisiting the Li-rich giant problem (2016)
Journal Article
Casey, A., Ruchti, G., Masseron, T., Randich, S., Gilmore, G., Lind, K., …Valentini, M. (2016). The Gaia-ESO Survey: revisiting the Li-rich giant problem. Monthly Notices of the Royal Astronomical Society, 461(3), 3336 - 3352. https://doi.org/10.1093/mnras/stw1512

The discovery of lithium-rich giants contradicts expectations from canonical stellar evolution. Here we report on the serendipitous discovery of 20 Li-rich giants observed during the Gaia-ESO Survey, which includes the first nine Li-rich giant stars... Read More about The Gaia-ESO Survey: revisiting the Li-rich giant problem.

The Gaia-ESO Survey: Lithium depletion in the Gamma Velorum cluster and inflated radii in low-mass pre-main-sequence stars (2016)
Journal Article
Jeffries. (2016). The Gaia-ESO Survey: Lithium depletion in the Gamma Velorum cluster and inflated radii in low-mass pre-main-sequence stars. Monthly Notices of the Royal Astronomical Society, 1456-1465. https://doi.org/10.1093/mnras/stw2458

We show that non-magnetic models for the evolution of pre-main-sequence (PMS) stars cannot simultaneously describe the colour–magnitude diagram (CMD) and the pattern of lithium depletion seen in the cluster of young, low-mass stars surrounding ?2 Vel... Read More about The Gaia-ESO Survey: Lithium depletion in the Gamma Velorum cluster and inflated radii in low-mass pre-main-sequence stars.

The Gaia-ESO Survey: Pre-Main Sequence Stars in the Young Open Cluster NGC 3293 (2016)
Journal Article
Delgado, A., Sampedro, L., Alfaro, E., Costado, M., Yun, J., Frasca, A., …Magrini, L. (2016). The Gaia-ESO Survey: Pre-Main Sequence Stars in the Young Open Cluster NGC 3293. Monthly Notices of the Royal Astronomical Society, 460(3), 3305-3315. https://doi.org/10.1093/mnras/stw1217

The young open cluster NGC3293 is included in the observing program of the Gaia-ESO survey (GES). The radial velocity values provided have been used to assign cluster membership probabilities by means of a single-variable parametric analysis. These m... Read More about The Gaia-ESO Survey: Pre-Main Sequence Stars in the Young Open Cluster NGC 3293.

The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr? (2016)
Journal Article
Bouvier, J., Lanzafame, A., Venuti, L., Klutsch, A., Jeffries, R., Frasca, A., …Zwitter, T. (2016). The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr?. Astronomy and Astrophysics, 590, Article A78. https://doi.org/10.1051/0004-6361/201628336

Context
The evolution of lithium abundance in cool dwarfs provides a unique probe of nonstandard processes in stellar evolution.

Aims
We investigate the lithium content of young low-mass stars in the 5 Myr old, star forming region NGC 2264 and i... Read More about The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr?.

The Gaia-ESO Survey: membership and initial mass function of the. Velorum cluster (2016)
Journal Article
Jeffries. (2016). The Gaia-ESO Survey: membership and initial mass function of the. Velorum cluster. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/201527875

Context. Understanding the properties of young open clusters, such as the initial mass function (IMF), star formation history, and dynamic evolution, is crucial for obtaining reliable theoretical predictions of the mechanisms involved in the star for... Read More about The Gaia-ESO Survey: membership and initial mass function of the. Velorum cluster.

The Gaia-ESO Survey: Dynamical analysis of the L1688 region in Ophiuchus (2016)
Journal Article
Jeffries, R., & Wright, N. J. (2016). The Gaia-ESO Survey: Dynamical analysis of the L1688 region in Ophiuchus. Astronomy and Astrophysics Supplement Series, https://doi.org/10.1051/0004-6361/201527253

The Gaia ESO Public Spectroscopic Survey (GES) is providing the astronomical community with high-precision measurements of many stellar parameters including radial velocities (RVs) of stars belonging to several young clusters and star-forming regions... Read More about The Gaia-ESO Survey: Dynamical analysis of the L1688 region in Ophiuchus.

The Gaia-ESO Survey: Stellar radii in the young open clusters NGC 2264, NGC 2547, and NGC 2516 (2016)
Journal Article
Jackson, R. J., Jeffries, R. D., Randich, S., Bragaglia, A., Carraro, G., Costado, M., …Zaggia, S. (2016). The Gaia-ESO Survey: Stellar radii in the young open clusters NGC 2264, NGC 2547, and NGC 2516. Astronomy and Astrophysics Supplement Series, 586, Article A52. https://doi.org/10.1051/0004-6361/201527507

Context. Rapidly rotating, low-mass members of eclipsing binary systems have measured radii that are significantly larger than predicted by standard evolutionary models. It has been proposed that magnetic activity is responsible for this radius infla... Read More about The Gaia-ESO Survey: Stellar radii in the young open clusters NGC 2264, NGC 2547, and NGC 2516.

The Gaia-ESO Survey: chemical signatures of rocky accretion in a young solar-type star (2015)
Journal Article
Jeffries. (2015). The Gaia-ESO Survey: chemical signatures of rocky accretion in a young solar-type star. Astronomy and Astrophysics Supplement Series, https://doi.org/10.1051/0004-6361/201526896

It is well known that newly formed planetary systems undergo processes of orbital reconfiguration and planetary migration. As a result, planets or protoplanetary objects may accrete onto the central star, being fused and mixed into its external layer... Read More about The Gaia-ESO Survey: chemical signatures of rocky accretion in a young solar-type star.

The Gaia-ESO Survey: empirical determination of the precision of stellar radial velocities and projected rotation velocities (2015)
Journal Article
Jeffries, & Jackson, R. (2015). The Gaia-ESO Survey: empirical determination of the precision of stellar radial velocities and projected rotation velocities. Astronomy and Astrophysics Supplement Series, https://doi.org/10.1051/0004-6361/201526248

Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very Large Telescope.

Aims. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for repr... Read More about The Gaia-ESO Survey: empirical determination of the precision of stellar radial velocities and projected rotation velocities.

A kinematically unbiased search for nearby young stars in the Northern hemisphere selected using SuperWASP rotation periods (2015)
Journal Article
Binks, A., Jeffries, R., & Maxted, P. (2015). A kinematically unbiased search for nearby young stars in the Northern hemisphere selected using SuperWASP rotation periods. Monthly Notices of the Royal Astronomical Society, 452(1), 173-192. https://doi.org/10.1093/mnras/stv1309

We present a kinematically-unbiased search to identify young, nearby low-mass members of kinematic moving groups (MGs). Objects with both rotation periods shorter than 5 days in the SuperWASP All-Sky Survey and X-ray counterparts in the ROSAT All-Sky... Read More about A kinematically unbiased search for nearby young stars in the Northern hemisphere selected using SuperWASP rotation periods.

The Gaia-ESO Survey: A globular cluster escapee in the Galactic halo (2015)
Journal Article
Jeffries. (2015). The Gaia-ESO Survey: A globular cluster escapee in the Galactic halo. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/201425554

A small fraction of the halo field is made up of stars that share the light element (Z = 13) anomalies characteristic of second generation globular cluster (GC) stars. The ejected stars shed light on the formation of the Galactic halo by tracing the... Read More about The Gaia-ESO Survey: A globular cluster escapee in the Galactic halo.

The Gaia-ESO survey: Discovery of a spatially extended low-mass population in the Vela OB2 association (2015)
Journal Article
Jeffries. (2015). The Gaia-ESO survey: Discovery of a spatially extended low-mass population in the Vela OB2 association. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/201425367

The nearby (distance ~ 350–400 pc), rich Vela OB2 association, includes ?2 Velorum, one of the most massive binaries in the solar neighbourhood and an excellent laboratory for investigating the formation and early evolution of young clusters. Recent... Read More about The Gaia-ESO survey: Discovery of a spatially extended low-mass population in the Vela OB2 association.

The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705 (2015)
Journal Article
Jeffries. (2015). The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/201424989

Context. The Gaia-ESO Public Spectroscopic Survey will observe a large sample of clusters and cluster stars, covering a wide age-distance-metallicity-position-density parameter space.

Aims. We aim to determine C, N, and O abundances in stars of Ga... Read More about The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705.

The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars (2014)
Journal Article
Smiljanic, R., Korn, A., Bergemann, M., Frasca, A., Magrini, L., Masseron, T., …Zaggia, S. (2014). The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars. Astronomy and Astrophysics, 570, Article A122. https://doi.org/10.1051/0004-6361/201423937

Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 105 stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already... Read More about The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars.

The effect of star-spots on the ages of low-mass stars determined from the lithium depletion boundary (2014)
Journal Article
Jackson, R. J., & Jeffries, R. D. (2014). The effect of star-spots on the ages of low-mass stars determined from the lithium depletion boundary. Monthly Notices of the Royal Astronomical Society, 445(4), 2111-2123. https://doi.org/10.1093/mnras/stu2076

In a coeval group of low-mass stars, the luminosity of the sharp transition between stars that retain their initial lithium and those at slightly higher masses in which Li has been depleted by nuclear reactions, the lithium depletion boundary (LDB),... Read More about The effect of star-spots on the ages of low-mass stars determined from the lithium depletion boundary.

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.

The low-mass Initial Mass Function in the young cluster NGC 6611 (2009)
Journal Article
Jeffries, M. Oliveira, J., D. Jeffries, R., & Th. van Loon, J. (2009). The low-mass Initial Mass Function in the young cluster NGC 6611. Monthly Notices of the Royal Astronomical Society, 1034-1050. https://doi.org/10.1111/j.1365-2966.2008.14140.x

NGC 6611 is the massive young cluster (2-3 Myr) that ionises the Eagle Nebula. We present very deep photometric observations of the central region of NGC 6611 obtained with the Hubble Space Telescope and the following filters: ACS/WFC F775W and F850L... Read More about The low-mass Initial Mass Function in the young cluster NGC 6611.

The lithium depletion boundary in NGC 2547 as a test of pre-main-sequence evolutionary models (2005)
Journal Article
Jeffries, R. D., & Oliveira, J. M. (2005). The lithium depletion boundary in NGC 2547 as a test of pre-main-sequence evolutionary models. Monthly Notices of the Royal Astronomical Society, 358(1), 13 -29. https://doi.org/10.1111/j.1365-2966.2005.08820.x

Intermediate resolution spectroscopy from the ESO Very Large Telescope is analysed for 63 photometrically selected low-mass (0.08-0.30 Msun) candidates of the open cluster NGC 2547. We have confirmed membership for most of these stars using radial ve... Read More about The lithium depletion boundary in NGC 2547 as a test of pre-main-sequence evolutionary models.