Rob Jeffries

Trumpler 14 (JHK)

My Research

I investigate the early lives of sun-like and lower mass stars at ages from when they emerge from their birth sites at 1 million years until they reach the Hydrogen-burning main sequence at 10-100 million years.


The goal is to understand whether our solar system is an "ordinary" outcome of the star and planetary formation process and sample the diversity of circumstellar environments during the epoch of planet formation.


Using ground based and satellite observatories such as the ESO VLT, the William Herschel, Spitzer and XMM-Newton telescopes I observe young stellar clusters and test theories for the formation and evolution of stars and their planetary systems.


My refereed publications (as listed on NASA ADS).


ResearchGate Profile


Trumpler 14 (JHK)

Recent Results

NGC 1960 (by Emil Ivanov)

A dynamical study of young stars in the Gamma Vel cluster - first results from the Gaia-ESO survey.
The Gaia-ESO survey is conducting a massive spectroscopic investigation of representative stellar populations in our Galaxy using the Flames fibre spectrograph at the VLT. We have published the first kinematic study of a young star forming region using Gaia-ESO data. The exquisite velocity precision separates the low-mass stars surrounding the massive Wolf-Rayet binary, Gamma Velorum, into two distinct populations, one slightly older than the other. The older population is more centrally concentrated around Gamma Vel and may be gravitationally bound. The apparent youth of Gamma Vel compared to its lower-mass siblings suggest a star forming scenario in which the massive binary formed last in a clustered environment.

Jeffries et al. 2014, Astronomy & Astrophysics, 563, A94

ESO image of Beta Pic

A lithium depletion boundary age of 21 million years for the Beta Pic moving group.
As low-mass PMS stars contract, their cores heat up until hot enough to burn lithium. The luminosity at which stars switch from having no lithium to preserving all their initial lithium at only slightly lower luminosities, turns out to be an almost model-independent age indicator. We have used spectra from the Isaac Newton and Nordic Optical Telescopes on La Palma to find a new lithium age of 21+/-4 million years for a moving group of nearby stars that surround the Sun and include the bright star Beta Pictoris. These are vital targets for direct imaging searches for young, hot exoplanets and circumstellar debris. Our age is older than the 12 million years usually assumed for this group and makes the inferred mass of any discovered companions larger by about 30 percent.

Binks and Jeffries 2014, MNRAS Letters, 438, L11-L15

Ongoing Projects

  • (1) XMM-Newton X-ray observations of flaring in young Suns.
  • (2) Spitzer investigations of debris disks at the epoch of terrestrial planet formation.

  • (3) Using VLT spectroscopy to find star formation histories in young clusters.

  • (4) Estimating ages and age spreads in young clusters using fibre spectroscopy to assess lithium depletion.

  • (5) Looking for surface contamination in young stars due to the accretion of planetary material.

  • (6) Investigating the radii and magnetic activity of young, rapidly rotating M-dwarfs.

Collaborations

I work at Keele along with STFC-funded PDRA Richard Jackson, and PhD students Amy Dobson and Alex Binks)

I have a long standing collaboration with Tim Naylor and co-workers at University of Exeter - The "Cluster Collaboration". We have compiled photometric catalogues for many young clusters and associations.

I am a member of the steering group and active participant in the Gaia-ESO spectroscopic survey. A very large (300 night) public survey of stellar populations using the Flames Spectrograph on the VLT. Keele has been part of a team reducing data from the multi-fibre Giraffe instrument, improving the sky subtraction and radial velocity precision.