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Laporte N.,University of Santiago de Chile | Infante L.,University of Santiago de Chile | Iribarren P.T.,University of Santiago de Chile | Zheng W.,Johns Hopkins University | And 23 more authors.
Astrophysical Journal | Year: 2016

In this paper we present the results of our search for and study of z ≳ 6 galaxy candidates behind the third Frontier Fields (FFs) cluster, MACS J0717.5+3745, and its parallel field, combining data from Hubble and Spitzer. We select 39 candidates using the Lyman break technique, for which the clear non-detection in optical make the extreme mid-z interlopers hypothesis unlikely. We also take benefit from z ≳ 6 samples selected using the previous FF data sets of Abell 2744 and MACS 0416 to improve the constraints on the properties of very high redshift objects. We compute the redshift and the physical properties such emission lines properties, star formation rate, reddening, and stellar mass for all FF objects from their spectral energy distribution using templates including nebular emission lines. We study the relationship between several physical properties and confirm the trend already observed in previous surveys for evolution of star formation rate with galaxy mass and between the size and the UV luminosity of our candidates. The analysis of the evolution of the UV luminosity function with redshift seems more compatible with an evolution of density. Moreover, no robust z ≥ 8.5 object is selected behind the cluster field and few z ∼ 9 candidates have been selected in the two previous data sets from this legacy survey, suggesting a strong evolution in the number density of galaxies between z ∼ 8 and 9. Thanks to the use of the lensing cluster, we study the evolution of the star formation rate density produced by galaxies with L > 0.03 L∗, and confirm the strong decrease observed between z ∼ 8 and 9.

Madiedo J.M.,University of Huelva | Madiedo J.M.,University of Seville | Trigo-Rodriguez J.M.,Institute Of Ciencies Of Lespai Csic Ieec | Konovalova N.,Academy of Sciences of Tajikistan | And 5 more authors.
Astronomy and Astrophysics | Year: 2013

We present the observations of two fireballs that exhibit fast and quasi-periodic brightness variations along their atmospheric path. This phenomenon, which is known as "flickering", is associated to the entry of spinning non-spherical meteoroids into the atmosphere. Both bolides were imaged in the framework of the continuous fireball monitoring and meteor spectroscopy campaigns organized by the SPanish Meteor Network (SPMN) in 2012. Their atmospheric trajectory, radiant, and orbit were calculated. The preatmospheric mass and tensile strength of the parent meteoroids were also estimated, and the rotation of these bodies analyzed on the basis of the photometric behavior of the bolides. Although small (less than 80 grams), a non-zero terminal mass was determined for both events. The emission spectra produced during the ablation of the meteoroids in the atmosphere are also discussed. © ESO, 2013.

Sabby J.A.,Southern Illinois University at Edwardsville | Lacy C.H.S.,University of Arkansas | Ibanoglu C.,Ege University | Claret A.,Institute Astrofisica Of Andaluca
Astronomical Journal | Year: 2011

Accurate absolute properties are determined for the first time for the 3.15 day period eccentric eclipsing binary star FT Ori based on new absolute photometry, five differential light curves, and a radial velocity curve. The stars appear to be normal for their spectral types, A0 + A2. The orbit is highly eccentric (e = 0.409) and shows apsidal motion with a period of 536 years. The absolute properties and the degree of central mass concentration of the stars are consistent with current theoretical models at an age of 190Myr. © 2011. The American Astronomical Society. All rights reserved.

Guerrero M.A.,Institute Astrofisica Of Andaluca | Ramos-Larios G.,Institute Astrofisica Of Andaluca | Ramos-Larios G.,Institute Astronomia y Meteorologia | Massa D.,NASA
Publications of the Astronomical Society of Australia | Year: 2010

Since the IUE satellite produced a vast collection of high-resolution UV spectra of the central stars of planetary nebulae (CSPNe), there has not been any further systematic study of the stellar winds of these stars. The high spectral resolution, sensitivity and large number of archival observations in the FUSE archive allow the study of the stellar winds of CSPNe in the far-UV domain where lines of species spanning a wide excitation range can be observed. We present here a preliminary analysis of the P Cygni profiles of a sample of ∼60 CSPNe observed by FUSE. P Cygni profiles providing evidence for fast stellar winds with velocities between 200 and 4300 km s-1 have been found in 40 CSPNe. In many cases, this is the first time that fast stellar winds have been reported for these planetary nebulae (PNe). A detailed study of these far-UV spectra is on-going. © Astronomical Society of Australia 2010.

Troitskiy I.S.,Astronomical Institute of SPbU | Morozova D.A.,Astronomical Institute of SPbU | Jorstad S.G.,Astronomical Institute of SPbU | Larionov V.M.,Astronomical Institute of SPbU | And 4 more authors.
Proceedings of the International Astronomical Union | Year: 2014

We present results of 4 years of VLBA monitoring along with γ-ray and optical R-band photometric observations of 6 blazars (0420-014, 1156+295, 1222+216, PKS 1510-089, 1633+382 and CTA 102). We have analyzed total intensity images obtained with the VLBA at 43 GHz and investigated kinematic evolution of the pc-scale jets of the sources. For all sources we compare flux variations in the VLBI core and bright superluminal knots with γ-ray and optical light curves. The majority of γ-ray flares are coincident with the appearance of a new superluminal knot and/or a flare in the millimeter-wave core and at optical wavelengths. These results support the conclusion that for many flares in blazars the region of the enhanced γ-ray and optical emission is located in the vicinity or downstream of the mm-wave VLBI core. Copyright © International Astronomical Union 2014.

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