Spectral Type and Radial Velocity Variations in Three SRC Variables

SRC variables are M supergiants, precursors to Type II supernovae, that vary in brightness with moderately regular periods of order 100-1000 days. Although identified as pulsating stars that obey their own period-luminosity relation, few have been examined in enough detail to follow the temperature and spectral changes that they undergo during their long cycles. The present study examines such changes for several SRC variables revealed by CCD spectra obtained at the Dominion Astrophysical Observatory (DAO) during 2005-2009, as well as by archival spectra from the DAO (and elsewhere) for some stars from the 1960s to 1980s, and Cambridge radial velocity spectrometer measures for Betelgeuse. Described here is our classification procedure and information on the spectral type and radial velocity changes in three of the stars. The results provide insights into the pulsation mechanism in M supergiants.Comment: To appear in the Odessa Variable Stars 2010 conference proceedings (see http://uavso.org.ua/?page=vs2010), edited by I. Andronov and V. Kovtyuk

NESS: Using a Microsatellite to Search For and Track Satellites and Asteroids

The Near Earth Space Surveillance (NESS) mission is being developed by Dynacon and a team of asteroid scientists, supported by the Canadian Space Agency (CSA) and the Canadian Department of National Defence (DND). NESS uses a single satellite to perform a dual mission: searching for an tracking Earth-approaching asteroids, and tracking satellites in Earth orbit. There are aspects of both of these activities that are best accomplished using an orbiting observatory. The concept presented here is to implement NESS using a small imaging telescope mounted on a lowcost microsatellite-class platform, based on the design developed for the MOST stellar photometry microsatellite mission

A Dark Core in Abell 520

The rich cluster Abell 520 (z=0.201) exhibits truly extreme and puzzling multi-wavelength characteristics. It may best be described as a "cosmic train wreck." It is a major merger showing abundant evidence for ram pressure stripping, with a clear offset in the gas distribution compared to the galaxies (as in the bullet cluster 1E 0657-558). However, the most striking feature is a massive dark core (721 h_70 M_sun/L_sun) in our weak lensing mass reconstruction. The core coincides with the central X-ray emission peak, but is largely devoid of galaxies. An unusually low mass to light ratio region lies 500 kpc to the east, and coincides with a shock feature visible in radio observations of the cluster. Although a displacement between the X-ray gas and the galaxy/dark matter distributions may be expected in a merger, a mass peak without galaxies cannot be easily explained within the current collisionless dark matter paradigm. Interestingly, the integrated gas mass fraction (~0.15), mass-to-light ratio (220 h_70 M_sun/L_sun), and position on the X-ray luminosity-temperature and mass-temperature relations are unremarkable. Thus gross properties and scaling relations are not always useful indicators of the dynamical state of clusters.Comment: 10 pages, 5 figures, accepted for publication in the Astrophysical Journal, higher resolution version at http://visav.phys.uvic.ca/~amahdav

Revisión sistemática sobre las aplicaciones en E-turismo en el periodo 2004 - 2014

La investigación tiene como propósito presentar una revisión sistemática del uso de las Tecnologías de la Información (TI) en el sector del turismo, publicados en la literatura científica entre los años 2004 y 2014 se pretende construir un marco conceptual que permita explicar qué es el e-Turismo y sus características más importantes, planear la revisión sistemática, estableciendo las preguntas de investigación, el alcance de la revisión y los criterios a considerar para la selección y clasificación de los documentos, buscar los documentos en las bases de datos seleccionadas utilizando para ello una ecuación de búsqueda depurada, seleccionar los documentos a ser analizados a través de una evaluación de calidad de los mismos, realizar el análisis de los documentos seleccionados y presentar una síntesis de los resultados obtenidos, se encontró que para los años 2004 a 2014 se ha venido incrementando la investigación del desarrollo e implementación de tecnologías de la información como apoyo a los diferentes sectores que componen el turismo, a saber: Hospitalidad, Guías Turísticas y Transporte; en especial el uso de aplicaciones web y la geolocalización (GPS), este trabajo logra sentar las bases para futuras investigaciones donde sea necesario determinar qué tipo de relación existe entre las diferentes aplicaciones que se utilizan para apoyar los servicios en el e-Turismo; así como a nivel general, establecer un marco de referencia para un modelo de e-Inclusión asociado con otras disciplinas, como por ejemplo, el e-Gobierno, e-Salud, entre otros. El campo del turismo es uno de los dominios donde se observan más avances a nivel tecnológico, a lo largo de los años se han desarrollado todo tipo de aplicaciones que buscan soportar toda la cadena de valor del turismo, desde los prestadores de servicios, como los hoteles y las aerolíneas, los intermediadores como las agencias de turismo, así como los usuarios finales, los turistas

COMET 169P/NEAT(=2002 EX 12 ): THE PARENT BODY OF THE α-CAPRICORNID METEOROID STREAM

ABSTRACT The Jupiter-family comet 169P/NEAT (previously known as asteroid 2002 EX 12 ) has a dynamical association with the α-Capricornid meteoroid stream. In this paper, we present photometric observations of comet 169P/NEAT to further investigate the physical characters of its disintegration state related to the stream. The comet shows a point-like surface brightness profile limiting contamination due to coma emission to ∼4% at most, indicating no evidence of outgassing. An upper limit on the fraction of the surface that could be sublimating water ice of <10 −4 is obtained with an upper limit to the mass loss of ∼10 −2 kg s −1 . The effective radius of nucleus is found to be 2.3 ± 0.4 km. Red filter photometry yields a rotational period of 8.4096 ± 0.0012 hr, and the range of the amplitude 0.29 ± 0.02 mag is indicative of a moderately spherical shape having a projected axis ratio ∼1.3. The comet shows redder colors than the Sun, being compatible with other dead comet candidates. The calculated lost mass per revolution is ∼10 9 kg. If it has sustained this mass loss over the estimated 5000 yr age of the α-Capricornid meteoroid stream, the total mass loss from 169P/NEAT (∼10 13 kg) is consistent with the reported stream mass (∼ 10 13 -10 15 kg), suggesting that the stream is the product of steady disintegration of the parent at every return

Evidence for a colour dependence in the size distribution of main belt asteroids

We present the results of a project to detect small (~1 km) main-belt asteroids with the 3.6 meter Canada-France-Hawaii Telescope (CFHT). We observed in 2 filters (MegaPrime g' and r') in order to compare the results in each band. Owing to the observational cadence we did not observe the same asteroids through each filter and thus do not have true colour information. However strong differences in the size distributions as seen in the two filters point to a colour-dependence at these sizes, perhaps to be expected in this regime where asteroid cohesiveness begins to be dominated by physical strength and composition rather than by gravity. The best fit slopes of the cumulative size distributions (CSDs) in both filters tend towards lower values for smaller asteroids, consistent with the results of previous studies. In addition to this trend, the size distributions seen in the two filters are distinctly different, with steeper slopes in r' than in g'. Breaking our sample up according to semimajor axis, the difference between the filters in the inner belt is found to be somewhat less pronounced than in the middle and outer belt, but the CSD of those asteroids seen in the r' filter is consistently and significantly steeper than in g' throughout. The CSD slopes also show variations with semimajor axis within a given filter, particularly in r'. We conclude that the size distribution of main belt asteroids is likely to be colour dependent at kilometer sizes and that this dependence may vary across the belt.Comment: 28 pages, 5 figures, submitted to the Astronomical Journa

Bright Variable Stars in NGC 6819 - An Open Cluster in the Kepler Field

We describe a variability study of the moderately old open cluster NGC 6819. We have detected 4 new detached eclipsing binaries near the cluster turnoff (one of which may be in a triple system). Several of these systems should be able to provide mass and radius information, and can therefore constrain the age of the cluster. We have also newly detected one possible detached binary member about 3.5 magnitudes below the turnoff. One EW-type binary (probably not a cluster member) shows unusually strong night-to-night light curve variations in sets of observations separated by 8 years. According to the best current information, the three brightest variables we detected (2 of them new) are cluster members, making them blue stragglers. One is a delta Scu pulsating variable, one is a close but detached binary, and the third contains a detached short period binary that shows total eclipses. In each case, however, there is evidence hinting that the system may have been produced through the interaction of more than two stars.Comment: 33 pages, 15 figures, accepted to A

Discovery of the host cluster for the fundamental Cepheid calibrator Zeta Geminorum

Publisher's Version/PDFNew and existing CORAVEL, UBVJHKs, HST, HIP/Tycho, ARO, KPNO, and DAO observations imply that the fundamental Cepheid calibrator ζ Gem is a cluster member. The following parameters were inferred for ζ Gem from cluster membership and are tied to new spectral classifications (DAO) established for 26 nearby stars (e.g., HD53588/B7.5IV, HD54692/B9.5IV): E B−V = 0.02±0.02, log τ = 7.85±0.15, and d = 355±15 pc. The mean distance to ζ Gem from cluster membership and six recent estimates (e.g., IRSB) is d = 363 ± 9(σx̄) ± 26(σ) pc.The results presented here support the color-excess and HST parallax derived for the Cepheid by Benedict et al. Forthcoming precise proper motions (DASCH) and Chandra/XMM-Newton observations of the broader field may be employed to identify cluster members, bolster the cluster’s existence, and provide stronger constraints on the Cepheid’s fundamental parameters