A Dusty M5 Binary in the beta Pictoris Moving Group

We report the identification of a new wide separation binary (LDS 5606) in the ~20 Myr-old beta Pic moving group. This M5+M5 pair has a projected separation of 26'', or ~1700 AU at a distance of 65 pc. Both stars host warm circumstellar disks and many strong hydrogen and helium emission lines. Spectroscopic observations reveal signatures of youth for both stars and on-going mass accretion in the primary. The properties of LDS 5606 make it an older analog to the ~8 Myr TWA 30 system, which is also composed of a pair of widely separated mid-M dwarfs, each hosting their own warm circumstellar disks. LDS 5606 joins a rather exclusive club of only 3 other known stellar systems where both members of a binary, far from any molecular cloud, are orbited by detected circumstellar disks.Comment: 8 pages, 6 figures; Accepted for publication in A&

The impact of air pollution on cognitive function

The impact of air pollution (AP) on cognitive function is widely understudied. Currently, most evidence focuses on correlating chronic AP exposure to performance on off-the-shelf cognitive tests in children and ageing participants. This thesis aimed to investigate the impact of both acute and chronic AP exposure on attention, socio-emotional processing, and episodic memory in clinically health adult populations using specially designed behavioural tasks. Using both experimental and quasi-experimental methods, participants were exposed to AP from a range of sources including Particulate Matter (PM) through candle burning; Traffic-related Air Pollution (TRAP) through quasi-experimental measurements during commuting; and Diesel Exhaust (DE) though the use of an atmosphere chamber. Participants in all studies were clinically healthy adults aged between 18 and 50 with no history of cardiovascular or neurological disease. Results indicated a reduction in pro-social behaviour 24 hours following acute exposure to PM and TRAP and lower cognitive control 4 hours following acute exposure to DE. Critically, no immediate effect of acute AP exposure was identified on these functions. The delay between exposure and cognitive dysfunction is suggestive of inflammatory mechanisms as a likely explanation for the identified effects. An immediate deficit in spatiotemporal encoding ability following acute TRAP exposure was identified, suggestive of hypoxia as a mechanistic explanation. However, no episodic encoding difficulties were identified after PM or DE exposure, nor any effect of any AP species on recall ability. This suggests that episodic memory is preserved despite the identified socio-emotional and executive deficits. Chronic exposure was quantified using participant residential postcodes throughout the lifetime. Higher chronic AP exposure was associated with lower cognitive control, indicative of neurodegeneration or stunted neurodevelopment. Together, the findings highlight an impact of AP on the quality and ease of decision making, emotional control, and learning of new information. These processes are critical to successfully navigate the complex ever-changing human environment, and degradation of these processes could lead to risk-taking, aggression, and degradation of mental health

Deep search for companions to probable young brown dwarfs

We have obtained high contrast images of four nearby, faint, and very low mass objects 2MASSJ04351455-1414468, SDSSJ044337.61+000205.1, 2MASSJ06085283-2753583 and 2MASSJ06524851-5741376 (here after 2MASS0435-14, SDSS0443+00, 2MASS0608-27 and 2MASS0652-57), identified in the field as probable isolated young brown dwarfs. Our goal was to search for binary companions down to the planetary mass regime. We used the NAOS-CONICA adaptive optics instrument (NACO) and its unique capability to sense the wavefront in the near-infrared to acquire sharp images of the four systems in Ks, with a field of view of 28"*28". Additional J and L' imaging and follow-up observations at a second epoch were obtained for 2MASS0652-57. With a typical contrast DKs= 4.0-7.0 mag, our observations are sensitive down to the planetary mass regime considering a minimum age of 10 to 120 Myr for these systems. No additional point sources are detected in the environment of 2MASS0435-14, SDSS0443+00 and 2MASS0608-27 between 0.1-12" (i.e about 2 to 250 AU at 20 pc). 2MASS0652-57 is resolved as a \sim230 mas binary. Follow-up observations reject a background contaminate, resolve the orbital motion of the pair, and confirm with high confidence that the system is physically bound. The J, Ks and L' photometry suggest a q\sim0.7-0.8 mass ratio binary with a probable semi-major axis of 5-6 AU. Among the four systems, 2MASS0652-57 is probably the less constrained in terms of age determination. Further analysis would be necessary to confirm its youth. It would then be interesting to determine its orbital and physical properties to derive the system's dynamical mass and to test evolutionary model predictions.Comment: Research note, 5 pages, 2 tables and 3 figures, accepted to A&

Comparing Programming Self-Esteem of Upper Secondary School Teachers to CS1 Students

Teacher self-esteem has been found to impact student learning in a number of non-computing fields. As computing slowly becomes a part of the upper secondary school (high school) curriculum in many countries, instruments designed to measure teachers’ programming self-esteem can help inform classroom practice and processes such as teacher professional development needs. This study examines if there are differences in programming self-esteem (using the Bergin Programming Self-Esteem Instrument) between upper secondary school teachers and CS1 students in Ireland. In addition this study provides evidence of validity when using this instrument (originally developed for CS1 students) to measure upper secondary school teacher programming self-esteem. To test for evidence of validity, we compared the results of the programming self-esteem construct given to upper secondary school teachers (n=130) to a recent study of programming selfesteem among CS1 students (n=693). We found evidence of both reliability and validity with teachers that aligns with the evidence found for the CS1 students, demonstrating utility for use with teacher cohorts. Comparing these findings, teachers reported statistically significantly lower programming self-esteem compared to CS1 students. Interestingly CS1 students identifying as male had a statistically significant higher programming self-esteem than those identifying as female. However, we found no statistically significant difference for teacher gender, unlike previous work. Our results indicate that teacher programming self-esteem should be given consideration in the design and implementation of professional development

The GALEX nearby young-star survey

We describe a method that exploits data from the Galaxy Evolution Explorer (GALEX) ultraviolet and Wide-field Infrared Survey Explorer and Two Micron All Sky Survey infrared source catalogs, combined with proper motions and empirical pre-main sequence is

Resolving the L/T transition binary SDSS J2052-1609 AB

Binaries provide empirical key constraints for star formation theories, like the overall binary fraction, mass ratio distribution and the separation distribution. They play a crucial role to calibrate the output of theoretical models, like absolute magnitudes, colors and effective temperature depending on mass, metallicity and age. We present first results of our on-going high-resolution imaging survey of late type brown dwarfs. The survey aims at resolving tight brown dwarf binary systems to better constrain the T dwarf binary fraction. We intent to follow-up the individual binaries to determine orbital parameters. Using NACO at the VLT we performed AO-assisted near-infrared observations of SDSS J2052-1609. High-spatial resolution images of the T1 dwarf were obtained in H and Ks filters. We resolved SDSS J2052-1609 into a binary system with a separation of 0.101" \pm 0.001". Archival data from HST/NICMOS taken one year previous to our observations proves the components to be co-moving. Using the flux ratio between the components we infer J, H and Ks magnitudes for the resolved system. From the near-IR colors we estimate spectral types of T1 +1 -4 and T2.5 \pm 1 for component A and B, respectively. A first estimate of the total system mass yields Mtot > 78 Mjup, assuming a circular orbit.Comment: 5 pages, 3 figures, 3 tables, accepted for publication by A&

A focus on L dwarfs with trigonometric parallaxes

This is an author-created, un-copyedited version of an article published in Publications of the Astronomical Society of the Pacific. Under embargo until 14 May 2019. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1538-3873/aaacc5.We report new parallax measurements for ten L and early T type dwarfs, five of which have no previous published values, using observations over 3 years at the robotic Liverpool Telescope. The resulting parallaxes and proper motions have median errors of 2\,mas and 1.5\,mas/year respectively. Their space motions indicate they are all Galactic disk members. We combined this sample with other objects with astrometry from the Liverpool Telescope and with published literature astrometry to construct a sample of 260 L and early T type dwarfs with measured parallaxes, designated the Astrometry Sample. We study the kinematics of the Astrometry Sample, and derived a solar motion of $(U,V,W)_{\bigodot} = (7.9\pm1.7,13.2\pm1.2,7.2\pm1.0)$\,\kms~ with respect to the local standard of rest, in agreement with recent literature. We derive a kinematic age of 1.5-1.7\,Gyr for the Astrometry Sample assuming the age increases monotonically with the total velocity for a given disk sample. This kinematic age is less than half literature values for other low mass dwarf samples. We believe this difference arises for two reasons (1) the sample is mainly composed of mid to late L dwarfs which are expected to be relatively young and (2) the requirement that objects have a measured parallax biases the sample to the brighter examples which tend to be younger.Peer reviewedFinal Accepted Versio

A new L-dwarf member of the moderately metal-poor triple system HD 221356

We report on the discovery of a fourth component in the HD 221356 star system, previously known to be formed by an F8V, slightly metal-poor primary ([Fe/H]=-0.26), and a distant M8V+L3V pair. In our ongoing common proper motion search based on VISTA Hemisphere Survey (VHS) and 2MASS catalogues, we have detected a faint (J=13.76+/-0.04 mag) co-moving companion of the F8 star located at angular separation of 12.13+/-0.18 arcsec (position angle of 221.8+/-1.7), corresponding to a projected distance of ~312 AU at 26 pc. Near-infrared spectroscopy of the new companion, covering the 1.5-2.4 micron wavelength range with a resolving power of R~600, indicates an L1+/-1 spectral type. Using evolutionary models the mass of the new companion is estimated at ~0.08 solar masses, which places the object close to the stellar-substellar borderline. This multiple system provides an interesting example of objects with masses slightly above and below the hydrogen burning mass limit. The low mass companions of HD 221356 have slightly bluer colours than field dwarfs with similar spectral type, which is likely a consequence of the sub-solar metallicity of the system.Comment: 7 pages, 4 figures, accepted for publication in MNRA

Parallaxes of southern extremely cool objects (PARSEC). II : Spectroscopic follow-up and parallaxes of 52 targets

We present near-infrared spectroscopy for 52 ultracool dwarfs, including two newly discovered late-M dwarfs, one new late-M subdwarf candidate, three new L, and four new T dwarfs. We also present parallaxes and proper motions for 21 of them. Four of the targets presented here have previous parallax measurements, while all the others are new values. This allow us to populate further the spectral sequence at early types (L0-L4). Combining the astrometric parameters with the new near-infrared spectroscopy presented here, we are able to investigate further the nature of some of the objects. In particular, we find that the peculiar blue L1 dwarf SDSS J133148.92-011651.4 is a metal-poor object, likely a member of the galactic thick disk. We discover a new M subdwarf candidate, 2MASS J20115649-6201127. We confirm the low-gravity nature of EROS-MP J0032-4405, DENIS-P J035726.9-441730, and 2MASS J22134491-2136079. We present two new metal-poor dwarfs: the L4pec 2MASS J19285196-4356256 and the M7pec SIPS2346-5928. We also determine the effective temperature and bolometric luminosity of the 21 targets with astrometric measurements, and we obtain a new polynomial relation between effective temperature and near-infrared spectral type. The new fit suggests a flattening of the sequence at the transition between M and L spectral types. This could be an effect of dust formation, which causes a more rapid evolution of the spectral features as a function of the effective temperature.Peer reviewe