Millimeter-wave Searches for Cold Dust and Molecular Gas around T Tauri Stars in MBM 12

We report results of a sensitive search for cold dust and molecular gas in the disks around 8 T Tauri stars in the high-latitude cloud MBM 12. Interferometric observations of 3 mm continuum emission in 5 fields containing 6 of the objects, and literature values for the remaining two, limit the disk masses to M_disk < 0.04 - 0.09 M_sun (gas+dust), for a gas:dust mass ratio of 100 and a distance of 275 pc. By coadding the 3 mm data of our five fields, we set an upper limit to the average disk mass of (N=5) < 0.03 M_sun. Simultaneous observation of the CS J=2-1 and the N2H+ 1-0 lines show no emission. Single-dish observations of the 13CO 2-1 line limit the disk mass to (5 - 10) * 10^-4 M_sun for a standard CO abundance of 2 * 10^-4. Depletion of CO by up to two orders of magnitude, through freezing out or photodissociation, can reconcile these limits. These mass limits lie within the range found in the Taurus-Auriga and rho Oph star-forming regions (0.001 - 0.3 M_sun), and preclude conclusions about possible decrease in disk mass over the 1 - 2 Myr age range spanned by the latter two regions and MBM 12. Our observations can exclude the presence in MBM 12 of T Tauri stars with relatively bright and massive disks such as T Tau, DG Tau, and GG Tau.Comment: 17 pages, 3 figures, uses AASTeX, accepted by The Astronomical Journa

Photometric Redshifts for Galaxies in the GOODS Southern Field

We use extensive multi-wavelength photometric data from the Great Observatories Origins Deep Survey (GOODS) to estimate photometric redshifts for a sample of 434 galaxies with spectroscopic redshifts in the Chandra Deep Field South. Using the Bayesian method, which incorporates redshift/magnitude priors, we estimate photometric redshifts for galaxies in the range 18 < R (AB) < 25.5, giving an rms scatter of 0.11. The outlier fraction is < 10%, with the outlier-clipped rms being 0.047. We examine the accuracy of photometric redshifts for several, special sub--classes of objects. The results for extremely red objects are more accurate than those for the sample as a whole, with rms of 0.051 and very few outliers (3%). Photometric redshifts for active galaxies, identified from their X-ray emission, have a dispersion of 0.104, with 10% outlier fraction, similar to that for normal galaxies. Employing a redshift/magnitude prior in this process seems to be crucial in improving the agreement between photometric and spectroscopic redshifts.Comment: Accepted for publication in ApJ

The FORS Deep Field Spectroscopic Survey

We present a catalogue and atlas of low-resolution spectra of a well defined sample of 341 objects in the FORS Deep Field. All spectra were obtained with the FORS instruments at the ESO VLT with essentially the same spectroscopic set-up. The observed extragalactic objects cover the redshift range 0.1 to 5.0. 98 objects are starburst galaxies and QSOs at z > 2. Using this data set we investigated the evolution of the characteristic spectral properties of bright starburst galaxies and their mutual relations as a function of the redshift. Significant evolutionary effects were found for redshifts 2 < z < 4. Most conspicuous are the increase of the average C IV absorption strength, of the dust reddening, and of the intrinsic UV luminosity, and the decrease of the average Ly alpha emission strength with decreasing redshift. In part the observed evolutionary effects can be attributed to an increase of the metallicity of the galaxies with cosmic age. Moreover, the increase of the total star-formation rates and the stronger obscuration of the starburst cores by dusty gas clouds suggest the occurrence of more massive starbursts at later cosmic epochs.Comment: 24 pages, 25 figures (35 PS files), 4 tables, accepted for publication in A&A. v2: minor typos corrected and references update

Ingeniando emprendimientos: una experiencia para el desarrollo emprendedor de los alumnos de la Facultad de Ingenieria de la UNLP

En la semana del 15 al 20 de Septiembre de 2014, la Facultad de Ingeniería de la Universidad Nacional de La Plata (UNLP), a través de la Unidad de Investigación, Desarrollo, Extensión y Transferencia de Formulación y Evaluación de Proyectos (UIDET FyEP) y la Prosecretaría de Desarrollo, Vinculación e Innovación Productiva, participó de la Semana Nacional del Emprendedor Tecnológico promovida por el Ministerio de Ciencia, Tecnología e Innovación Productiva de la Nación. Durante toda la semana se realizaron actividades en la sede del Colegio de Ingenieros de la Provincia de Buenos Aires Distrito V, institución colaboradora del evento. Las actividades estuvieron dirigidas a estudiantes de ingeniería de todas las carreras dictadas en la Facultad de Ingeniería de la UNLP y su objetivo fue promover la formación, incorporación de herramientas y desarrollo de habilidades en la detección de oportunidades de negocio de base científica y tecnológica. Para cumplir con el objetivo se realizaron actividades de formación en las temáticas de formulación y evaluación de proyectos, elaboración de planes de negocio y finanzas para emprendedores. De forma complementaria se llevaron a cabo diversas dinámicas de clase que buscaron desarrollar el espíritu emprendedor y habilidades necesarias para emprender en los participantes y se realizó un Concurso de Ideas-Proyecto donde los alumnos agrupados en equipos, elaboraron un plan de negocio en nivel de idea-perfil para dar respuesta a problemáticas actuales del país, presentadas el primer día de la semana. Al final de la semana un Comité Evaluador eligió a los ganadores del Concurso. En el presente trabajo se exponen la metodología, los temas tratados y los resultados y conclusiones obtenidos a partir de las actividades realizadas.Publicado en Terceras Jornadas de Investigación, Transferencia y Extensión. La Plata : Universidad Nacional de La Plata, 2015.Facultad de Ingenierí

The Size Evolution of High Redshift Galaxies

Hubble Space Telescope images of high-redshift galaxies selected via color and photometric redshifts are used to examine the size and axial-ratio distribution of galaxies as a function of redshift at lookback times t > 8 Gyr. These parameters are measured at rest-frame UV wavelengths (1200-2000 Angstroms) on images with a rest-frame resolution of less than 0.8 kpc. Galaxy radii are found to scale with redshift approximately as the inverse of the Hubble parameter H(z). This is in accord with the theoretical expectation that the typical sizes of the luminous parts of galaxies should track the expected evolution in the virial radius of dark-matter halos. The mean ratio of semi-major to semi-minor axis for a bright well-resolved sample of galaxies at z ~ 4 is b/a = 0.65, suggesting that these Lyman break galaxies are not drawn from a spheroidal population. However the median concentration index of this sample is C = 3.5, which is closer to the typical concentration indices, C ~ 4, of nearby elliptical galaxies than to the values, C<2 for local disk galaxies of type Sb and later.Comment: 5 pages, including 3 figures; uses emulateapj style; accepted by ApJL for publication in a special issue of early GOODS result

Qualitative identification of copper bearing minerals using near infrared sensors

Application of sensors for on-site fast identification and discrimination of dominant ore bearing particles from associated gangues in a complex ore is an important route in minerals exploration and extraction industries. This paper considers identification and discrimination of copper bearing minerals from associated gangues using near infrared sensors. Different copper bearing minerals in the Akiri copper ore are differentiated on the basis of their near infrared spectra behaviour. The near infrared spectra of individual samples are correlated with their mineralogy and chemistry as analysed by X-Ray diffraction and X-Ray fluorescence equipment, respectively. The obtained results indicated that the detection limit of the near infrared sensor is better than that of both X-ray diffraction and X-ray fluorescence equipment used. Hence, in addition to the minerals identified by the X-ray diffraction equipment, other near infrared active minerals with concentration below the X-ray diffraction detection limit were also detected by the near infrared sensors