Showing papers by "University of Hertfordshire published in 2009"

Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2015).

Abstract: Changes to virus taxonomy approved and ratified by the International Committee on Taxonomy of Viruses in February 2015 are listed.

The Systems Biology Graphical Notation

Abstract: Circuit diagrams and Unified Modeling Language diagrams are just two examples of standard visual languages that help accelerate work by promoting regularity, removing ambiguity and enabling software tool support for communication of complex information. Ironically, despite having one of the highest ratios of graphical to textual information, biology still lacks standard graphical notations. The recent deluge of biological knowledge makes addressing this deficit a pressing concern. Toward this goal, we present the Systems Biology Graphical Notation (SBGN), a visual language developed by a community of biochemists, modelers and computer scientists. SBGN consists of three complementary languages: process diagram, entity relationship diagram and activity flow diagram. Together they enable scientists to represent networks of biochemical interactions in a standard, unambiguous way. We believe that SBGN will foster efficient and accurate representation, visualization, storage, exchange and reuse of information on all kinds of biological knowledge, from gene regulation, to metabolism, to cellular signaling.

Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

Abstract: Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gamma-ray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.

Galaxy cluster X-ray luminosity scaling relations from a representative local sample (REXCESS)

Abstract: We examine the X-ray luminosity scaling relations of 31 nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS). The objects are selected only in X-ray luminosity, optimally sampling the cluster luminosity function. Temperatures range from 2 to 9 keV, and there is no bias toward any particular morphological type. To reduce measurement scatter we extract pertinent values in an aperture corresponding to R500, estimated using the tight correlation between YX (the product of gas mass and temperature) and total mass. The data exhibit power law relations between bolometric X-ray luminosity and temperature, YX and total mass, all with slopes that are significantly steeper than self-similar expectations. We examine the possible causes for the steepening, finding that structural variations have little effect and that the primary driver appears to be a systematic variation of the gas content with mass. Scatter about the relations is dominated in all cases by the presence of cool cores. The natural logarithmic scatter about the raw X-ray luminosity-temperature relation is about 70 per cent, and about the X-ray luminosity-YX relation it is 40 per cent. Systems with more morphological substructure show similar scatter about scaling relations than clusters with less substructure, due to the preponderance of cool core systems in the regular cluster subsample. Cool core and morphologically disturbed systems occupy distinct regions in the residual space with respect to the best fitting mean relation, the former lying systematically at the high luminosity side, the latter lying systematically at the low luminosity side. Simple exclusion of the central regions serves to reduce the scatter about the scaling relations by more than a factor of two. The scatter reduces by a similar amount with the use of the central gas density as a third parameter. Using YX as a total mass proxy, we derive a Malmquist bias-corrected local luminosity-mass relation and compare with other recent determinations. Our results indicate that luminosity can be a reliable mass proxy with controllable scatter, which has important implications for upcoming all-sky cluster surveys, such as those to be undertaken with Planck and eROSITA ,a nd ultimately for the use of the cluster population for cosmological purposes.

Heracles: the hera co line extragalactic survey

Abstract: Original article can be found at: http://www.iop.org/EJ/journal/1538-3881 Copyright American Astronomical Society. DOI: 10.1088/0004-6256/137/6/4670 [Full text of this article is not available in the UHRA]

A limit on the variation of the speed of light arising from quantum gravity effects

Abstract: A cornerstone of Einstein's special relativity is Lorentz invariance-the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l(Planck) approximate to 1.62 x 10(-33) cm or E(Planck) = M(Planck)c(2) approximate to 1.22 x 10(19) GeV), at which quantum effects are expected to strongly affect the nature of space-time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy(1-7). Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in gamma-ray burst (GRB) light-curves(2). Here we report the detection of emission up to similar to 31GeV from the distant and short GRB090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E(Planck) on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l(Planck)/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories(3,6,7) in which the quantum nature of space-time on a very small scale linearly alters the speed of light.

Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies

Abstract: We investigate a class of rapidly growing emission line galaxies, known as “Green Peas,” first noted by volunteers in the Galaxy Zoo project because of their peculiar bright green colour and small size, unresolved in SDSS imaging. Their appearance is due to very strong optical emission lines, namely [O III] �5007 ˚ A, with an unusually large equivalent width of up to �1000 ˚ A. We discuss a well-defined sample of 251 colour-selected ob jects, most of which are strongly star forming, although there are some AGN interlopers including 8 newly discovered Narrow Line Seyfert 1 galaxies. The star-forming Peas are low mass galaxies (M� 10 8.5 10 10 M⊙) with high star formation rates (� 10 M⊙yr −1 ), low metallicities (log[O/H] + 12 �8.7) and low reddening (E(B V) 6 0.25) and they reside in low density environments. They have some of the highest specific star for mation rates (up to � 10 −8 yr −1 ) seen in the local Universe, yielding doubling times for their stellar mass of hundreds of Myrs. The few star-forming Peas with HST imaging appear to have several clumps of bright star-forming regions and low surface density features that may indicate recent or ongoing mergers. The Peas are similar in size, mass, luminosity and metallicity to Luminous Blue Compact Galaxies. They are also similar to high redshift UV-luminous galaxies, e.g., Lymanbreak galaxies and Lyman-� emitters, and therefore provide a local laboratory with which to study the extreme star formation processes that occur in high-redshift galaxies. Studying starbursting galaxies as a function of redshift is essential to u nderstanding the build up of stellar mass in the Universe.

Fermi Observations of GRB 090902B: A Distinct Spectral Component in the Prompt and Delayed Emission

Abstract: We report on the observation of the bright, long gamma-ray burst (GRB), GRB 090902B, by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board the Fermi observatory. ...

What is driving the h i velocity dispersion

Abstract: Original article can be found at: http://www.iop.org/EJ/journal/1538-3881 Copyright American Astronomical Society. DOI: 10.1088/0004-6256/137/5/4424 [Full text of this article is not available in the UHRA]

Environment and self-regulation in galaxy formation

Abstract: The environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology-density relationship. In this paper we study the effect of environment on the evolution of early-type galaxies by analysing the stellar population properties of 3,360 galaxies morphologically selected by visual inspection from the SDSS in the redshift range 0.05

The ethics of information transparency

Abstract: The paper investigates the ethics of information transparency (henceforth transparency). It argues that transparency is not an ethical principle in itself but a pro-ethical condition for enabling or impairing other ethical practices or principles. A new definition of transparency is offered in order to take into account the dynamics of information production and the differences between data and information. It is then argued that the proposed definition provides a better understanding of what sort of information should be disclosed and what sort of information should be used in order to implement and make effective the ethical practices and principles to which an organisation is committed. The concepts of "heterogeneous organisation" and "autonomous computational artefact" are further defined in order to clarify the ethical implications of the technology used in implementing information transparency. It is argued that explicit ethical designs, which describe how ethical principles are embedded into the practice of software design, would represent valuable information that could be disclosed by organisations in order to support their ethical standing.

From Isolation to Communication: A Case Study Evaluation of Robot Assisted Play for Children with Autism with a Minimally Expressive Humanoid Robot

Abstract: The general context of the work presented in this paper is assistive robotics with our long-term aim to support children with autism This paper is part of the Aurora project that studies ways in which robotic systems can encourage basic communication and social interaction skills in children with autism This paper investigates how a small minimally expressive humanoid robot KASPAR can assume the role of a social mediator - encouraging children with low functioning autism to interact with the robot, to break their isolation and importantly, to facilitate interaction with other people The article provides a case study evaluation of segments of trials where three children with autism, who usually do not interact with other people in their day to day activity, interacted with the robot and with co-present adults A preliminary observational analysis was undertaken which applied, in abbreviated form, certain principles from conversation analysis - notably attention to the context in which the target behaviour occurred The analysis was conducted by a social psychologist with expertise in using conversation analysis to understand interactions involving persons with an ASD The analysis emphasises aspects of embodiment and interaction kinesics and revealed unexpected competencies on the part of the children It showed how the robot served as a salient object mediating and encouraging interaction between the children and co-present adults

galev evolutionary synthesis models – I. Code, input physics and web interface

Abstract: GALEV (GALaxy EVolution) evolutionary synthesis models describe the evolution of stellar populations in general, of star clusters as well as of galaxies, both in terms of resolved stellar populations and of integrated light properties over cosmological time-scales of ≥13 Gyr from the onset of star formation shortly after the big bang until today. For galaxies, GALEV includes a simultaneous treatment of the chemical evolution of the gas and the spectral evolution of the stellar content, allowing for what we call a chemically consistent treatment: we use input physics (stellar evolutionary tracks, stellar yields and model atmospheres) for a large range of metallicities and consistently account for the increasing initial abundances of successive stellar generations. Here we present the latest version of the GALEV evolutionary synthesis models that are now interactively available at http://www.galev.org. We review the currently used input physics, and also give details on how this physics is implemented in practice. We explain how to use the interactive web interface to generate models for user-defined parameters and also give a range of applications that can be studied using GALEV, ranging from star clusters, undisturbed galaxies of various types E–Sd to starburst and dwarf galaxies, both in the local and the high-redshift Universe.

Galaxy Zoo: 'Hanny's Voorwerp', a quasar light echo?

Abstract: We report the discovery of an unusual object near the spiral galaxy IC 2497, discovered by visual inspection of the Sloan Digital Sky Survey (SDSS) as part of the Galaxy Zoo project. The object, known as Hanny’s Voorwerp, is bright in the SDSS g band due to unusually strong [O III]4959, 5007 emission lines. We present the results of the first targeted observations of the object in the optical, ultraviolet and X-ray, which show that the object contains highly ionized gas. Although the line ratios are similar to extended emission-line regions near luminous active galactic nucleus (AGN), the source of this ionization is not apparent. The emission-line properties, and lack of X-ray emission from IC 2497, suggest either a highly obscured AGN with a novel geometry arranged to allow photoionization of the object but not the galaxy’s own circumnuclear gas, or, as we argue, the first detection of a quasar light echo. In this case, either the luminosity of the central source has decreased dramatically or else the obscuration in the system has increased within 10 5 yr. This object may thus represent the first direct probe

KASPAR --a minimally expressive humanoid robot for human--robot interaction research

Abstract: This paper provides a comprehensive introduction to the design of the minimally expressive robot KASPAR, which is particularly suitable for human--robot interaction studies. A low-cost design with off-the-shelf components has been used in a novel design inspired from a multi-disciplinary viewpoint, including comics design and Japanese Noh theatre. The design rationale of the robot and its technical features are described in detail. Three research studies will be presented that have been using KASPAR extensively. Firstly, we present its application in robot-assisted play and therapy for children with autism. Secondly, we illustrate its use in human--robot interaction studies investigating the role of interaction kinesics and gestures. Lastly, we describe a study in the field of developmental robotics into computational architectures based on interaction histories for robot ontogeny. The three areas differ in the way as to how the robot is being operated and its role in social interaction scenarios. Each will be introduced briefly and examples of the results will be presented. Reflections on the specific design features of KASPAR that were important in these studies and lessons learnt from these studies concerning the design of humanoid robots for social interaction will also be discussed. An assessment of the robot in terms of utility of the design for human--robot interaction experiments concludes the paper.

Modified-Release Hydrocortisone to Provide Circadian Cortisol Profiles

Abstract: Context: Cortisol has a distinct circadian rhythm regulated by the brain’s central pacemaker. Loss of this rhythm is associated with metabolic abnormalities, fatigue, and poor quality of life. Conventional glucocorticoid replacement cannot replicate this rhythm. Objectives: Our objectives were to define key variables of physiological cortisol rhythm, and by pharmacokinetic modeling test whether modified-release hydrocortisone (MR-HC) can provide circadian cortisol profiles. Setting: The study was performed at a Clinical Research Facility. Design and Methods: Using data from a cross-sectional study in healthy reference subjects (n = 33), we defined parameters for the cortisol rhythm. We then tested MR-HC against immediate-release hydrocortisone in healthy volunteers (n = 28) in an open-label, randomized, single-dose, cross-over study. We compared profiles with physiological cortisol levels, and modeled an optimal treatment regimen. Results: The key variables in the physiological cortisol profile included: ...

Lipid models for united-atom molecular dynamics simulations of proteins

Abstract: United-atom force fields for molecular dynamics (MD) simulations provide a higher computational efficiency, especially in lipid membrane simulations, with little sacrifice in accuracy, when compared to all-atom force fields. Excellent united-atom lipid models are available, but in combination with depreciated protein force fields. In this work, a united-atom model of the lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine has been built with standard parameters of the force field GROMOS96 53a6 that reproduces the experimental area per lipid of a lipid bilayer within 3% accuracy to a value of 0.623 ± 0.011 nm(2) without the assumption of a constant surface area or the inclusion of surface pressure. In addition, the lateral self-diffusion constant and deuterium order parameters of the acyl chains are in agreement with experimental data. Furthermore, models for 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) result in areas per lipid of 0.625 nm(2) (DMPC), 0.693 nm(2) (POPC), and 0.700 nm(2) (POPG) from 40 ns MD simulations. Experimental lateral self-diffusion coefficients are reproduced satisfactorily by the simulation. The lipid models can form the basis for molecular dynamics simulations of membrane proteins with current and future versions of united-atom protein force fields.

The global gas and dust budget of the Large Magellanic Cloud: AGB stars and supernovae, and the impact on the ISM evolution

Abstract: We report on an analysis of the gas and dust budget in the the interstellar medium (ISM) of the Large Magellanic Cloud (LMC). Recent observations from the Spitzer Space Telescope enable us to study the mid-infrared dust excess of asymptotic giant branch (AGB) stars in the LMC. This is the first time we can quantitatively assess the gas and dust input from AGB stars over a complete galaxy, fully based on observations. The integrated mass-loss rate over all intermediate and high mass-loss rate carbon-rich AGB candidates in the LMC is 8.5 × 10 −3 M⊙ yr −1 , up to 2.1 × 10 −2 M⊙ yr −1 . This number could be increased up to 2.7×10 −2 M⊙ yr −1 if oxygen-rich stars are included. This is overall consistent with theoretical expectations, considering the star formation rate when these low- and intermediate-mass stars where formed, and the initial mass functions. AGB stars are one of the most important gas sources in the LMC, with supernovae (SNe), which produces about 2–4×10 −2 M⊙ yr −1 . At the moment, the star formation rate exceeds the gas feedback from AGB stars and SNe in the LMC, and the current star formation depends on gas already present in the ISM. This suggests that as the gas in the ISM is exhausted, the star formation rate will eventually decline in the LMC, unless gas is supplied externally. Our estimates suggest ‘a missing dust-mass problem’ in the LMC, which is similarly found in high-z galaxies: the accumulated dust mass from AGB stars and possibly SNe over the dust life time (400–800Myrs) is significant less than the dust mass in the ISM. Another dust source is required, possibly related to star-forming regions.

Genome-wide association study identifies variants at 9p21 and 22q13 associated with development of cutaneous nevi.

Abstract: A high melanocytic nevi count is the strongest known risk factor for cutaneous melanoma. We conducted a genome-wide association study for nevus count using 297,108 SNPs in 1,524 twins, with validation in an independent cohort of 4,107 individuals. We identified strongly associated variants in MTAP, a gene adjacent to the familial melanoma susceptibility locus CDKN2A on 9p21 (rs4636294, combined P = 3.4 x 10(-15)), as well as in PLA2G6 on 22q13.1 (rs2284063, combined P = 3.4 x 10(-8)). In addition, variants in these two loci showed association with melanoma risk in 3,131 melanoma cases from two independent studies, including rs10757257 at 9p21, combined P = 3.4 x 10(-8), OR = 1.23 (95% CI = 1.15-1.30) and rs132985 at 22q13.1, combined P = 2.6 x 10(-7), OR = 1.23 (95% CI = 1.15-1.30). This provides the first report of common variants associated to nevus number and demonstrates association of these variants with melanoma susceptibility.

DISCOVERY OF A GIANT Lyα EMITTER NEAR THE REIONIZATION EPOCH

Abstract: We report the discovery of a giant Lyα emitter (LAE) with a Spitzer/Infrared Array Camera (IRAC) counterpart near the reionization epoch at z = 6.595. The giant LAE is found from the extensive 1 deg2 Subaru narrowband survey for z = 6.6 LAEs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and subsequently identified by deep spectroscopy of Keck/DEIMOS and Magellan/IMACS. Among our 207 LAE candidates, this LAE is not only the brightest narrowband object with L(Lyα) = 3.9 ± 0.2 × 1043 erg s–1 in our survey volume of 106 Mpc3, but also a spatially extended Lyα nebula with the largest isophotal area whose major axis is at least 3''. This object is more likely to be a large Lyα nebula with a size of 17 kpc than to be a strongly lensed galaxy by a foreground object. Our Keck spectrum with medium-high spectral and spatial resolutions suggests that the velocity width is v FWHM = 251 ± 21 km s–1, and that the line-center velocity changes by 60 km s–1 in a 10 kpc range. The stellar mass and star formation rate are estimated to be 0.9-5.0 × 1010 M ☉ and >34 M ☉ yr–1, respectively, from the combination of deep optical to infrared images of Subaru, UKIDSS-Ultra Deep Survey, and Spitzer/IRAC. Although the nature of this object is not yet clearly understood, this could be an important object for studying cooling clouds accreting onto a massive halo, or forming-massive galaxies with significant outflows contributing to cosmic reionization and metal enrichment of intergalactic medium.

GRB 080503: implications of a naked short gamma-ray burst dominated by extended emission

Abstract: We report on observations of GRB 080503, a short gamma-ray burst (GRB) with very bright extended emission (about 30 times the gamma-ray fluence of the initial spike) in conjunction with a thorough comparison to other short Swift events. In spite of the prompt-emission brightness, however, the optical counterpart is extraordinarily faint, never exceeding 25 mag in deep observations starting at ~1 hr after the Burst Alert Telescope (BAT) trigger. The optical brightness peaks at ~1 day and then falls sharply in a manner similar to the predictions of Li & Paczynski (1998) for supernova-like emission following compact binary mergers. However, a shallow spectral index and similar evolution in X-rays inferred from Chandra observations are more consistent with an afterglow interpretation. The extreme faintness of this probable afterglow relative to the bright gamma-ray emission argues for a very low density medium surrounding the burst (a naked GRB), consistent with the lack of a coincident host galaxy down to 28.5 mag in deep Hubble Space Telescope imaging. The late optical and X-ray peak could be explained by a slightly off-axis jet or by a refreshed shock. Our observations reinforce the notion that short GRBs generally occur outside regions of active star formation, but demonstrate that in some cases the luminosity of the extended prompt emission can greatly exceed that of the short spike, which may constrain theoretical interpretation of this class of events. This extended emission is not the onset of an afterglow, and its relative brightness is probably either a viewing-angle effect or intrinsic to the central engine itself. Because most previous BAT short bursts without observed extended emission are too faint for this signature to have been detectable even if it were present at typical level, conclusions based solely on the observed presence or absence of extended emission in the existing Swift sample are premature.

The active nuclei of z < 1.0 3CRR radio sources

Abstract: We combine Chandraand XMM-NewtonX-ray data from our previous papers with new X-ray observations and with Spitzer mid-infrared data in order to study the nature of the nuclei o f radio galaxies and radio-loud quasars with z < 1.0 from the 3CRR sample. The significant increase in sample size over our previous work, the reduction of bias in the sample as a result of new observations, and the availability of more mid-infrared data allow us to show conclusively that almost all objects classed as low-excitation ra dio galaxies in optical spectroscopic studies lack a radiatively efficient active nucleus. We show that the distribution of absorbing columns in the narrow-line radio galaxies differs from the population of X-ray-selected radioquiet type-2 quasars and from that in local Seyfert 2s. We comment on the current evidence for the nature of the soft X-ray component in radio-galaxy nuclear spectra, concluding that a jet origin for this component is very hard to evade. Finally, we discuss the recently discovered ‘fundamental plane’ of black hole activity, showing th at care must be taken when placing radio-loud AGN on such diagnostic diagrams.

Primary care and dementia: 1. diagnosis, screening and disclosure

Abstract: Objectives To write a narrative review of the roles of primary care practitioners in caring for people with dementia in the community.Methods The systematic review carried out for the NICE/SCIE Guidelines was updated from January 2006, Cochrane Reviews were identified, and other publications found by consultation with experts.Results The insidious and very variable development of dementia syndromes makes recognition of the syndrome problematic in primary care. Dementia is probably under-diagnosed and under treated with an estimated 50% of primary care patients over 65 not diagnosed by their primary care physicians. This problem of under-diagnosis is probably not due to lack of diagnostic skills, but rather to the interaction of case-complexity, pressure on time and the negative effects of reimbursement systems. Primary care physicians often over-estimate the prevalence of dementia syndromes, but in some countries may also overestimate the prevalence of vascular dementia compared with Alzheimer's disease. Diagnosis is a step-wise process which can be aided by use of a cognitive function test, of which there are a number suitable for primary care use. Evidence based practice protocols can enhance detection rates in primary care, and there is growing evidence that communication skills in talking to people with dementia about dementia can be improved. Nevertheless there are multiple obstacles to bringing recognition forward in time, both in public awareness and professional understanding of the early changes in dementia.Conclusions There is insufficient evidence of benefit to justify population screening in primary care but earlier recognition of people with dementia syndrome is possible within primary care. The diagnosis of dementia is a shared responsibility between generalist and specialist disciplines. Primary care physicians should explore patients' ideas and concerns around their symptoms prior to referral and tentatively discuss possible diagnoses. Once the diagnosis has been confirmed, the primary care physician should provide both practical and emotional support to allow the patient and their family to come to terms with living with dementia, and refer them for additional psychosocial support if required. Copyright (C) 2009 John Wiley & Sons, Ltd.

Lithium Abundances of Extremely Metal-Poor Turnoff Stars

Abstract: We have determined Li abundances for eleven metal-poor turnoff stars, among which eight have [Fe/H] < -3, based on LTE analyses of high-resolution spectra obtained with the High Dispersion Spectrograph on the Subaru Telescope. The Li abundances for four of these eight stars are determined for the first time by this study. Effective temperatures are determined by a profile analysis of H alpha and H beta. While seven stars have Li abundances as high as the Spite Plateau value, the remaining four objects with [Fe/H] < -3 have A(Li) = log(Li/H) + 12 less than or similar to 2.0, confirming the existence of extremely metal-poor (EMP) turnoff stars having low Li abundances, as reported by previous work. The average of the Li abundances for stars with [Fe/H]< -3 is lower by 0.2 dex than that of the stars with higher metallicity. No clear constraint on the metallicity dependence or scatter of the Li abundances is derived from our measurements for the stars with [Fe/H]< -3. Correlations of the Li abundance with effective temperatures, with abundances of Na, Mg, and Sr, and with the kinematical properties are investigated, but no clear correlation is seen in the EMP star sample.

Rotational velocities for m dwarfs

Abstract: We present spectroscopic rotation velocities (v sin i) for 56 M dwarf stars using high-resolution Hobby-Eberly Telescope High Resolution Spectrograph red spectroscopy. In addition, we have also determined photometric effective temperatures, masses, and metallicities ([Fe/H]) for some stars observed here and in the literature where we could acquire accurate parallax measurements and relevant photometry. We have increased the number of known v sin i values for mid M stars by around 80% and can confirm a weakly increasing rotation velocity with decreasing effective temperature. Our sample of v sin is peak at low velocities (~3 km s–1). We find a change in the rotational velocity distribution between early M and late M stars, which is likely due to the changing field topology between partially and fully convective stars. There is also a possible further change in the rotational distribution toward the late M dwarfs where dust begins to play a role in the stellar atmospheres. We also link v sin i to age and show how it can be used to provide mid-M star age limits. When all literature velocities for M dwarfs are added to our sample, there are 198 with v sin i ≤ 10 km s–1 and 124 in the mid-to-late M star regime (M3.0-M9.5) where measuring precision optical radial velocities is difficult. In addition, we also search the spectra for any significant Hα emission or absorption. Forty three percent were found to exhibit such emission and could represent young, active objects with high levels of radial-velocity noise. We acquired two epochs of spectra for the star GJ1253 spread by almost one month and the Hα profile changed from showing no clear signs of emission, to exhibiting a clear emission peak. Four stars in our sample appear to be low-mass binaries (GJ1080, GJ3129, Gl802, and LHS3080), with both GJ3129 and Gl802 exhibiting double Hα emission features. The tables presented here will aid any future M star planet search target selection to extract stars with low v sin i.