Publications (74)
Spatial Statistics in Star Forming Regions: Is Star Formation Driven By Column Density Alone?
Brendan Retter, Jennifer Hatchell, Tim Naylor
Star formation is known to occur more readily where more raw materials are available. This is often expressed by a 'Kennicutt-Schmidt' relation where the surface density of Young S…
Pre-main-sequence isochrones -- III. The Cluster Collaboration isochrone server
Cameron P. M. Bell, Jon M. Rees, Tim Naylor +4
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,…
Are pre-MS stars older than we thought?
Tim Naylor, N. J. Mayne
We present a consistent age ordering for young clusters and groups determined using the contraction of stars through their pre-main-sequence phase. We compare these with ages deriv…
HARPS3 for a Roboticized Isaac Newton Telescope
Samantha J. Thompson, Didier Queloz, Isabelle Baraffe +25
We present a description of a new instrument development, HARPS3, planned to be installed on an upgraded and roboticized Isaac Newton Telescope by end-2018. HARPS3 will be a high r…
Can variability account for apparent age spreads in OB association colour-magnitude diagrams?
Ben Burningham, Tim Naylor, S. P. Littlefair +1
We have investigated the role of photometric variability in causing the apparent age spreads observed in the colour-magnitude diagrams of OB associations. We have found that the co…
Spatial Statistics in Star Forming Regions: Testing the Limits of Randomness
Brendan Retter, Jennifer Hatchell, Tim Naylor
Observational studies of star formation reveal spatial distributions of Young Stellar Objects (YSOs) that are `snapshots' of an ongoing star formation process. Using methods from s…
Improving Catalogue Matching By Supplementing Astrometry with Additional Photometric Information
Tom J. Wilson, Tim Naylor
The matching of sources between photometric catalogues can lead to cases where objects of differing brightness are incorrectly assumed to be detections of the same source. The reje…
Are pre-main-sequence stars older than we thought?
Tim Naylor
We fit the colour-magnitude diagrams of stars between the zero-age main-sequence and terminal-age main sequence in young clusters and associations. The ages we derive are a factor…
An Anomalous Extinction Law in the Cep OB3b Young Cluster: Evidence for dust processing during gas dispersal
Thomas S. Allen, Jakub J. Prchlik, S. Thomas Megeath +4
We determine the extinction law through Cep OB3b, a young cluster of 3000 stars undergoing gas dispersal. The extinction is measured toward 76 background K giants identified with M…
The magnetically quiet solar surface dominates HARPS-N solar RVs during low activity
Ben S. Lakeland, Tim Naylor, Raphaëlle Haywood +15
Using images from the Helioseismic and Magnetic Imager aboard the \textit{Solar Dynamics Observatory} (SDO/HMI), we extract the radial-velocity (RV) signal arising from the suppres…
Empirical isochrones and relative ages for young stars, and the radiative-convective gap
N. J. Mayne, Tim Naylor, S. P. Littlefair +2
We have selected pre-main-sequence stars in 12 groups of notional ages ranging from 1 Myr to 35 Myrs, using heterogeneous membership criteria. Using these members we have construct…
Pre-main-sequence variability across the radiative-convective gap
Eric S. Saunders, Tim Naylor, Nathan Mayne +1
We use I band imaging to perform a variability survey of the 13 Myr-old cluster h Per. We find a significant fraction of the cluster members to be variable. Most importantly, we fi…
Low mass stars, brown dwarf candidates and the mass function of the young open cluster NGC 2547
R. D. Jeffries, Tim Naylor, C. R. Devey +1
We present a catalogue of RIZ photometry over an area of 0.855 square degrees, centred on NGC 2547. The survey is substantially complete to limits of R_c=21.5, I_c=19.5, Z=19.5. We…
Accretion-induced luminosity spreads in young clusters: evidence from stellar rotation
S. P. Littlefair, Tim Naylor, N. J. Mayne +2
We present an analysis of the rotation of young stars in the associations Cepheus OB3b, NGC 2264, NGC 2362 and the Orion Nebula Cluster (ONC). We discover a correlation between rot…
gr8stars I: A homogeneous spectroscopic study of bright FGKM dwarfs and a public library of their high-resolution spectra
Alix Violet Freckelton, Annelies Mortier, Megan Bedell +15
As the fields of stellar and exoplanetary study grow and revolutionary new detection instruments are created, it is imperative that a homogeneous, precise source of stellar paramet…
The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation
Shoko Jin, Scott C. Trager, Gavin B. Dalton +212
WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree…
The JCMT Transient Survey: Four Year Summary of Monitoring the Submillimeter Variability of Protostars
Yong-Hee Lee, Doug Johnstone, Jeong-Eun Lee +49
We present the four-year survey results of monthly submillimeter monitoring of eight nearby (pc) star-forming regions by the JCMT Transient Survey. We apply the Lomb-Scargl…
Age Gradients in the Stellar Populations of Massive Star Forming Regions Based on a New Stellar Chronometer
Konstantin V. Getman, Eric D. Feigelson, Michael A. Kuhn +6
A major impediment to understanding star formation in massive star forming regions (MSFRs) is the absence of a reliable stellar chronometer to unravel their complex star formation…
The Wide-Field Near Infrared Data: Optimal Photometry in Crowded Fields
R. R. King, Tim Naylor, Patrick S. Broos +2
We present JHK infrared data from the UK Infrared Telescope for a subset of the regions of the MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) survey. Some…
The Massive Star-Forming Regions Omnibus X-Ray Catalog, Second Installment
Leisa K. Townsley, Patrick S. Broos, Gordon P. Garmire +4
We present the second installment of the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC2), a compilation of X-ray point sources detected in Chandra/ACIS observati…
The MYStIX InfraRed-Excess Source Catalog
Matthew S. Povich, Michael A. Kuhn, Konstantin V. Getman +6
The MYStIX project (Massive Young Star-Forming Complex Study in Infrared and X-rays) provides a comparative study of 20 Galactic massive star-forming complexes (d = 0.4 to 3.6 kpc)…
Membership, binarity and accretion among very low-mass stars and brown dwarfs of the Sigma Orionis cluster
M. J. Kenyon, R. D. Jeffries, Tim Naylor +2
Intermediate resolution (R=7000) spectroscopy is presented for 76 photometrically selected very low mass (0.04<M<0.3M_{sun}) candidate members of the Sigma Orionis cluster. More th…
Overview of the Massive Young Star-Forming Complex Study in Infrared and X-ray (MYStIX) Project
Eric D. Feigelson, Leisa K. Townsley, Patrick S. Broos +16
MYStIX (Massive Young Star-Forming Complex Study in Infrared and Xray) seeks to characterize 20 OB-dominated young clusters and their environs at distances d < 4 kpc using imaging…
Rapid Circumstellar Disk Evolution and an Accelerating Star Formation Rate in the Infrared Dark Cloud M17 SWex
Matthew S. Povich, Leisa K. Townsley, Thomas P. Robitaille +5
We present a catalog of 840 X-ray sources and first results from a 100 ks Chandra X-ray Observatory imaging study of the filamentary infrared dark cloud G014.22500.506, which fo…
Exploring the M-dwarf Luminosity--Temperature--Radius Relationships using Gaia DR2
Sam Morrell, Tim Naylor
There is growing evidence that M-dwarf stars suffer radius inflation when compared to theoretical models, suggesting that models are missing some key physics required to completely…
A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
Cameron P. M. Bell, Eric E. Mamajek, Tim Naylor
We present a self-consistent, absolute isochronal age scale for young (< 200 Myr), nearby (< 100 pc) moving groups in the solar neighbourhood based on homogeneous fitting of semi-e…
The Keele-Exeter young cluster survey: I. Low mass pre-main sequence stars in NGC 2169
R. D Jeffries, J. M. Oliveira, Tim Naylor +2
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 (…
Bayesian Matching for X-ray and Infrared Sources in the MYStIX Project
Tim Naylor, Patrick S. Broos, Eric D. Feigelson
Identifying the infrared counterparts of X-ray sources in Galactic Plane fields such as those of the MYStIX project presents particular difficulties due to the high density of infr…
Observational Bias and Young Massive Cluster Characterisation I. 2D Perspective Effects
Anne S. M. Buckner, Kong You Liow, Clare L. Dobbs +2
Understanding the formation and evolution of high mass star clusters requires comparisons between theoretical and observational data to be made. Unfortunately, while the full phase…
The stellar association around Gamma Velorum and its relationship with Vela OB2
R. D Jeffries, Tim Naylor, F. M. Walter +2
We present the results of a photometric BVI survey of 0.9 square degrees around the Wolf-Rayet binary gamma^2 Vel and its early-type companion gamma^1 Vel. Several hundred PMS star…
Rotation of young stars in Cepheus OB3b
S. P. Littlefair, Tim Naylor, N. J. Mayne +2
We present a photometric study of I-band variability in the young association Cepheus OB3b. The study is sensitive to periodic variability on timescales of less than a day, to more…
New Methods for Determining the Ages of PMS Stars
Tim Naylor, N. J. Mayne, R. D. Jeffries +2
We present three new methods for determining the age of groups of pre-main-sequence stars. The first, creating empirical isochrones allows us to create a robust age ordering, but n…
Young Faithful: The Eruptions of EC 53 as It Cycles through Filling and Draining the Inner Disk
Yong-Hee Lee, Doug Johnstone, Jeong-Eun Lee +10
While young stellar objects sometimes undergo bursts of accretion, these bursts usually occur sporadically, making them challenging to study observationally and to explain theoreti…
Spitzer Imaging of the Nearby Rich Young Cluster, Cep OB3b
Thomas S. Allen, Robert A. Gutermuth, Erin Kryukova +7
We map the full extent of a rich massive young cluster in the Cep OB3b association with the IRAC and MIPS instruments aboard the {\it Spitzer} Space Telescope and the ACIS instrume…
Using Stellar Spectral Energy Distributions to Measure Exoplanet Parameters
Sam Morrell, Tim Naylor, John Southworth +1
The ability to make accurate determinations of planetary parameters is inextricably linked to measuring physical parameters of the host star, in particular the stellar radius. In t…
Pre-main-sequence isochrones -- II. Revising star and planet formation timescales
Cameron P. M. Bell, Tim Naylor, N. J. Mayne +2
We have derived ages for 13 young (<30 Myr) star-forming regions and find they are up to a factor two older than the ages typically adopted in the literature. This result has wide-…
Statistical Fitting of Evolution Models to Rotation Rates of Sun-Like Stars
Angela A. Breimann, Sean P. Matt, Tim Naylor
We apply for the first time a two-dimensional fitting statistic, , to rotational evolution models (REMs) of stars (0.1 to 1.3 ) on the period-mass plane. The $Ï^2…
Pre-main-sequence isochrones -- I. The Pleiades benchmark
Cameron P. M. Bell, Tim Naylor, N. J. Mayne +2
We present a critical assessment of commonly used pre-main-sequence isochrones by comparing their predictions to a set of well-calibrated colour-magnitude diagrams of the Pleiades…
An Autonomous Adaptive Scheduling Agent for Period Searching
Eric S. Saunders, Tim Naylor, Alasdair Allan
We describe the design and implementation of an autonomous adaptive software agent that addresses the practical problem of observing undersampled, periodic, time-varying phenomena…
On the Nature of Collinder 121: Insights from the Low-Mass Pre-Main Sequence
Ben Burningham, Tim Naylor, R. D. Jeffries +1
We present a VI photometric catalogue towards the open cluster Cr 121. XMM-Newton and ROSAT data are used to discover a low-mass pre-main sequence (PMS) along this sight-line. de Z…
A Contaminant-Free Catalogue of Gaia DR2-WISE Galactic Plane Matches: Including the Effects of Crowding in the Cross-Matching of Photometric Catalogues
Tom J Wilson, Tim Naylor
Faint, hidden contaminants in the point-spread functions (PSFs) of stars cause shifts to their measured positions. Wilson & Naylor (2017) showed failing to account for these shifts…
Gaia 17bpi: An FU Ori Type Outburst
Lynne A. Hillenbrand, Carlos Contreras Peña, Sam Morrell +7
We report on the source Gaia 17bpi and identify it as a new, ongoing FU Ori type outburst, associated with a young stellar object. The optical lightcurve from Gaia exhibited a 3.5…
A maximum likelihood method for fitting colour-magnitude diagrams
Tim Naylor, Rob Jeffries
We present a maximum likelihood method for fitting two-dimensional model distributions to stellar data in colour-magnitude space. This allows one to include (for example) binary st…
Determination of limits on disc masses around six pulsars at 15 and 90 microns
Lydie Koch-Miramond, Martin Haas, Eric Pantin +3
We have searched for evidence of emission at 15 microns with ISOCAM and at 90 microns with ISOPHOT from dust orbiting six nearby pulsars, both in binaries and in isolation, located…
Contamination and exclusion in the sigma Orionis young group
Ben Burningham, Tim Naylor, S. P. Littlefair +1
We present radial velocities for 38 low-mass candidate members of the sigma Orionis young group. We have measured their radial velocities by cross-correlation of high resolution (R…
The Spatial Structure of Young Stellar Clusters. I. Subclusters
Michael A. Kuhn, Eric D. Feigelson, Konstantin V. Getman +9
The clusters of young stars in massive star-forming regions show a wide range of sizes, morphologies, and numbers of stars. Their highly subclustered structures are revealed by the…
A Naive Bayes Classifier for identifying Class II YSOs
Andrew J. Wilson, Ben S. Lakeland, Tom J. Wilson +1
A naive Bayes classifier for identifying Class II YSOs has been constructed and applied to a region of the Northern Galactic Plane containing 8 million sources with good quality Ga…
Ages of young stars
David R. Soderblom, Lynne A. Hillenbrand, Rob D. Jeffries +2
Determining the sequence of events in the formation of stars and planetary systems and their time-scales is essential for understanding those processes, yet establishing ages is fu…
A lithium depletion boundary age of 22 Myr for NGC 1960
R. D. Jeffries, Tim Naylor, N. J. Mayne +2
We present a deep Cousins RI photometric survey of the open cluster NGC 1960, complete to R_C \simeq 22, I_C \simeq 21, that is used to select a sample of very low-mass cluster can…
Classification of Chandra X-ray Sources in Cygnus OB2
Vinay L. Kashyap, Mario G. Guarcello, Nicholas J. Wright +11
We have devised a predominantly Naive Bayes method to classify the optical/IR matches to X-ray sources detected by Chandra in the Cygnus OB2 association into foreground, member, an…
The Effect of Unresolved Contaminant Stars on the Cross-Matching of Photometric Catalogues
Tom J. Wilson, Tim Naylor
A fundamental process in astrophysics is the matching of two photometric catalogues. It is crucial that the correct objects be paired, and that their photometry does not suffer fro…
The age of Taurus - environmental effects on disc lifetimes
Jon M. Rees, T. Wilson, C. P. M. Bell +2
Using semi-empirical isochrones, we find the age of the Taurus star-forming region to be 3-4 Myr. Comparing the disc fraction in Taurus to young massive clusters suggests discs sur…
Characterising the i-band variability of YSOs over six orders of magnitude in timescale
Darryl J. Sergison, Tim Naylor, S. P. Littlefair +2
We present an -band photometric study of over 800 young stellar objects in the OB association Cep OB3b, which samples timescales from 1 minute to ten years. Using structure func…
Optimal photometry for colour-magnitude diagrams and its application to NGC 2547
Tim Naylor, E. J. Totten, R. D. Jeffries +3
We have developed the techniques required to use the optimal photometry algorithm of Naylor (1998) to create colour-magnitude diagrams with well defined completeness functions. To…
Fitting the young main-sequence; distances, ages and age spreads
N. J. Mayne, Tim Naylor
We use several main-sequence models to derive distances (and extinctions), with statistically meaningful uncertainties for 11 star-forming-regions and young clusters. The model dep…
V346 Normae: First post-outburst observations of an FU Orionis star
Stefan Kraus, Alessio Caratti o Garatti, Rebeca Garcia-Lopez +5
During their formation phase stars gain most of their mass in violent episodic accretion events, such as observed in FU Orionis (FUor) and EXor stars. V346 Normae is a well-studied…
Isochronal age scale of young moving groups in the solar neighbourhood
Cameron P. M. Bell, Eric E. Mamajek, Tim Naylor
We present a self-consistent, absolute isochronal age scale for young (< 200 Myr), nearby (< 100 pc) moving groups, which is consistent with recent lithium depletion boundary ages…
No evidence for intense, cold accretion onto YSOs from measurements of Li in T-Tauri stars
Darryl J. Sergison, N. J. Mayne, Tim Naylor +2
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 lit…
Identifying Young Stars in Massive Star-Forming Regions for the MYStIX Project
Patrick S. Broos, Konstantin V. Getman, Matthew S. Povich +6
The Massive Young star-forming Complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-form…
Mass segregation in the young open cluster NGC 2547
S. P. Littlefair, Tim Naylor, R. D. Jeffries +2
We present a study of mass segregation of the young (20-35 Myr isochronal age), open cluster NGC 2547. We find good evidence that mass segregation exists in NGC 2547 down to 3 Msun…
Observational Bias and Young Massive Cluster Characterisation II. Can Gaia accurately observe young clusters and associations?
Anne S. M. Buckner, Tim Naylor, Clare L. Dobbs +2
Observations of clusters suffer from issues such as completeness, projection effects, resolving individual stars and extinction. As such, how accurate are measurements and conclusi…
No disks around low-mass stars and brown dwarfs in the young sigma Orionis cluster?
J. M. Oliveira, R. D. Jeffries, M. J. Kenyon +2
We report on the analysis of 2MASS near-infrared data of a sample of low-mass stars and brown dwarfs in the sigma Orionis cluster. Youth and cluster membership have been spectrosco…
ABORAS: polarimetric, 10cm/s RV observations of the Sun as a star
Casper Farret Jentink, Annelies Mortier, Frans Snik +4
We present a description of A dual-Beam pOlarimetric Robotic Aperture for the Sun (ABORAS), to serve as a Solar input with a dedicated Stokes V polarimeter for the HARPS3 high-reso…
Evidence for high accretion-rates in Weak-Line T Tauri stars?
S. P. Littlefair, Tim Naylor, Tim J. Harries +2
We have discovered T Tauri stars which show startling spectral variability between observations seperated by 20 years. In spectra published by Bouvier & Appenzeller (1992) these ob…
Do accretion discs regulate the rotation of young stars?
S. P. Littlefair, Tim Naylor, Ben Burningham +1
We present a photometric study of I-band variability in the young cluster IC 348. The main purpose of the study was to identify periodic stars. In all we find 50 periodic stars, of…
Granulation on a quiet K dwarf: HD 166620 I. Spectral signatures as a function of line-formation temperature
Ancy Anna John, Khaled Al Moulla, Niamh K. O'Sullivan +14
As Radial velocity (RV) spectrographs reach unprecedented precision and stability below 1 m/s, the challenge of granulation in the context of exoplanet detection has intensified. D…
Submillimetre Transient Science in the Next Decade: EAO Submillimetre Futures White Paper Series, 2019
Steve Mairs, Gregory Herczeg, Doug Johnstone +11
This white paper gives a brief summary of the time domain science that has been performed with the JCMT in recent years and highlights the opportunities for continuing work in this…
T Tauri stellar magnetic fields: He I measurements
Neil H. Symington, Tim J. Harries, Ryuichi Kurosawa +1
We present measurements of the longitudinal magnetic field in the circumstellar environment of seven classical T Tauri stars. The measurements are based on high-resolution circular…
Autonomous software: Myth or magic?
Alasdair Allan, Tim Naylor, Eric S. Saunders
We discuss work by the eSTAR project which demonstrates a fully closed loop autonomous system for the follow up of possible micro-lensing anomalies. Not only are the initial micro-…
No wide spread of stellar ages in the Orion Nebula Cluster
R. D. Jeffries, S. P. Littlefair, Tim Naylor +1
The wide luminosity dispersion seen for stars at a given effective temperature in the H-R diagrams of young clusters and star forming regions is often interpreted as due to signifi…
Optimal placement of a limited number of observations for period searches
Eric S. Saunders, Tim Naylor, Alasdair Allan
Robotic telescopes present the opportunity for the sparse temporal placement of observations when period searching. We address the best way to place a limited number of observation…
MYStIX First Results: Spatial Structures of Massive Young Stellar Clusters
Michael A. Kuhn, Adrian Baddeley, Eric D. Feigelson +8
Observations of the spatial distributions of young stars in star-forming regions can be linked to the theory of clustered star formation using spatial statistical methods. The MYSt…
Kinematic structure in the young Sigma Orionis association
R. D. Jeffries, P. F. L. Maxted, J. M. Oliveira +1
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 spat…
Towards an understanding of YSO variability: A multi-wavelength analysis of bursting, dipping, and symmetrically varying light curves of disc-bearing YSOs
Ben S. Lakeland, Tim Naylor
Using simultaneous optical and infrared light curves of disc-bearing young stars in NGC 2264, we perform the first multi-wavelength structure function study of YSOs. We find that d…