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., Lanzafame, A., Drew, J., Eislöffel, J., Blomme, R., Morel, T., Lobel, A., Semaan, T., Randich, S., Jeffries, R., Micela, G., Vallenari, A., Kalari, V., Gilmore, G., Flaccomio, E., …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., Moraux, E., Biazzo, K., Messina, S., Micela, G., Randich, S., Stauffer, J., Cody, A., Flaccomio, E., Gilmore, G., Bayo, A., Bensby, T., Bragaglia, A., Carraro, G., Casey, 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., Flaccomio, E., Lanzafame, A., Lardo, C., Monaco, L., Morbidelli, L., Smiljanic, R., & 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.

Spectroscopic confirmation of M-dwarf candidate members of the Beta Pictoris and AB Doradus Moving Groups (2015)
Journal Article
Binks, A., & Jeffries, R. (2016). Spectroscopic confirmation of M-dwarf candidate members of the Beta Pictoris and AB Doradus Moving Groups. Monthly Notices of the Royal Astronomical Society, 455(3), 3345-3358. https://doi.org/10.1093/mnras/stv2431

Optical spectroscopic observations are reported for 24 and 23, nearby, proper-motion-selected M-dwarf candidate members of the Beta Pictoris and AB Doradus moving groups (BPMG and ABDMG). Using kinematic criteria, the presence of both Halpha emission... Read More about Spectroscopic confirmation of M-dwarf candidate members of the Beta Pictoris and AB Doradus Moving Groups.

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.

Pre-main-sequence isochrones - III: The Cluster Collaboration isochrone server (2014)
Journal Article
Jeffries. (2014). Pre-main-sequence isochrones - III: The Cluster Collaboration isochrone server. Monthly Notices of the Royal Astronomical Society, 3496 - 3511. https://doi.org/10.1093/mnras/stu1944

We present an isochrone server for semi-empirical pre-main-sequence model isochrones in the following systems: Johnson–Cousins, Sloan Digital Sky Survey, Two-Micron All-Sky Survey, Isaac Newton Telescope (INT) Wide-Field Camera and INT Photometric Ha... Read More about Pre-main-sequence isochrones - III: The Cluster Collaboration isochrone server.

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., Pancino, E., Ruchti, G., San Roman, I., Sbordone, L., Sousa, S., Tabernero, H., Tautvaišienė, G., Valentini, M., Weber, M., Worley, C., Zh. Adibekyan, V., Allende Prieto, C., Barisevičius, G., Biazzo, K., …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 Keele–Exeter young cluster survey – I. Low-mass pre-main-sequence stars in NGC 2169 (2007)
Journal Article
Jeffries, R., Oliveira, J., Naylor, T., Mayne, N., & Littlefair, S. (2007). The Keele–Exeter young cluster survey – I. Low-mass pre-main-sequence stars in NGC 2169. Monthly Notices of the Royal Astronomical Society, 376(2), 580 -598. https://doi.org/10.1111/j.1365-2966.2007.11327.x

We have used R_C I_C CCD photometry from the Isaac Newton telescope and intermediate resolution spectroscopy from the Gemini North telescope to identify and characterise low-mass (0.15<M/M_sun<1.3) pre-main sequence stars in the young open cluster NG...

Kinematic structure in the young σ Orionis association (2006)
Journal Article
Jeffries, R., Maxted, P., Oliveira, J., & Naylor, T. (2006). Kinematic structure in the young σ Orionis association. Monthly Notices of the Royal Astronomical Society, 371(1), L6 - L10. https://doi.org/10.1111/j.1745-3933.2006.00196.x

We have used precise radial velocity measurements for a large number of candidate low-mass stars and brown dwarfs, to show that the young Sigma Ori ``cluster'' consists of two spatially superimposed components which are kinematically separated by 7 k... Read More about Kinematic structure in the young σ Orionis association.

Circumstellar discs in the young σ Orionis cluster (2006)
Journal Article
Oliveira, J., Jeffries, R., Van Loon, J., & Rushton, M. (2006). Circumstellar discs in the young σ Orionis cluster. Monthly Notices of the Royal Astronomical Society, 369(1), 272 -280. https://doi.org/10.1111/j.1365-2966.2006.10299.x

We present new K- and L'-band imaging observations for members of the young (3-5 Myr) sigma Orionis cluster, obtained with UIST at UKIRT. We determine (K-L') colour excesses with respect to the photospheres, finding evidence for warm circumstellar du... Read More about Circumstellar discs in the young σ Orionis cluster.