Morphological classification of post-AGB stars

We present a complete study of the morphology of post-Asymptotic Giant Branch (AGB) stars. Post-AGB is a very short evolutionary phase between the end of the AGB and the beginning of the Planetary Nebula (PN) stage (between 100 and 10,000 yrs). We have defined the end of the post-AGB phase and the beginning of the PN phase when the star is hot enough to fully ionize the hydrogen envelope. Post-AGB stars have a circumstellar shell that is illuminated by the central stars or partially ionized. However, this circumstellar shell is too small to be resolved from ground-based observations. Thus, we have used data from the Hubble Space Telescope (HST) database to resolve these shells. About 150 post-AGB were found in this database. Here we present the preliminary results on their morphological classification and the correlation with several parameters such as galactic latitude and IRAS fluxes. Our preliminary results show that 40% of the sample are stellar-like (S), 33 % bipolar (B), 12 % multi-polar (M) and 15 % elliptical (E).Comment: proceedings of the conference "Why Galaxies Care About AGB Stars II", Vienna 2010, eds. Franz Kerschbaum, Thomas Lebzelter and Bob Wing, ASP Conf.Ser (in press

Signal Processing Techniques Intended for Peculiar Star Detection in APOGEE Survey

[Abstract] Like other disciplines, Astronomy faces the era of Big Data, where the analyses and discovery of specific objects is a significant and non-trivial matter. The APOGEE survey and Gaia mission are good examples of how these kind of projects have increased the amount of data to be managed. In this context, we have developed an algorithm to search for specific features in the APOGEE database. The main purpose is to seek spectral lines both in absorption or emission, in the whole APOGEE database, in order to find chemically-peculiar stars. We propose an algorithm which has been validated using cerium lines and we have applied it to the search for other chemical compounds.Ministerio de Ciencia, Innovación y Universidades; RTI2018-095076-B-C22Ministerio de Economía e Industria y Competitividad; ESP2016-80079-C2-2-RXunta de Galicia; ED431B 2018/4

Merging of Elliptical Galaxies as Possible Origin of the Intergalactic Stellar Population

We present N-body simulations of elliptical galaxy encounters into dry mergers to study the resulting unbound intergalactic stellar population, in particular that of the post-Main Sequence stars. The systems studied are pairs of spherical galaxies without dark halos. The stellar content of the model galaxies is distributed into mass-bins representing low- and intermediate-mass stars (0.85 -- 8 solar masses) according to Salpeter's initial mass function. Our models follow the dynamical evolution of galaxy encounters colliding head-on from initial low-energy parabolic or high-energy mildly-hyperbolic orbits, and for a choice of initial-mass ratios. The merging models with initial parabolic orbits have M2/M1 =1 and 10, and they leave behind respectively 5.5 % and 10 % of the total initial mass as unbound stellar mass. The merging model with initial hyperbolic orbit has M2/M1 =1, and leaves behind 21 % of its initial stellar mass as unbound mass, showing that the efficiency in producing intergalactic stars through a high-energy hyperbolic encounter is about four times than through a parabolic encounter of the same initial mass ratio. By assuming that all progenitor galaxies as well as the merger remnants are homologous systems we obtained that the intergalactic starlight is 17 % and 28 % of the total starlight respectively for the parabolic and hyperbolic encounters with M2/M1 =1. In all models, different mass stars have the same probability of becoming unbound and feeding the intergalactic stellar population.Comment: The Astrophysical Journal, in pres

High resolution imaging of NGC 2346 with GSAOI/GeMS: disentangling the planetary nebula molecular structure to understand its origin and evolution

We present high spatial resolution ($\approx$ 60--90 milliarcseconds) images of the molecular hydrogen emission in the Planetary Nebula (PN) NGC 2346. The data were acquired during the System Verification of the Gemini Multi-Conjugate Adaptive Optics System + Gemini South Adaptive Optics Imager. At the distance of NGC 2346, 700 pc, the physical resolution corresponds to $\approx$ 56 AU, which is slightly higher than that an [N II] image of NGC 2346 obtained with HST/WFPC2. With this unprecedented resolution we were able to study in detail the structure of the H$_2$ gas within the nebula for the first time. We found it to be composed of knots and filaments, which at lower resolution had appeared to be a uniform torus of material. We explain how the formation of the clumps and filaments in this PN is consistent with a mechanism in which a central hot bubble of nebular gas surrounding the central star has been depressurized, and the thermal pressure of the photoionized region drives the fragmentation of the swept-up shell.Comment: accepted in ApJ (17 pages, 7 figures, 1 Table

Influence of physical aspects and throwing velocity in opposition situation in top-elite and elite female handball players

The relationship between anthropometric and physical characteristics of female handball players and throwing velocity is considered an important factor in handball performance. The aim of this study was to examine key differences in anthropometric and fitness characteristics between top elite and elite female players competing in the first Spanish handball league. A total of 89 players from the first Spanish handball league were divided into two groups, top elite (38) and elite (51) players, and assessed for anthropometric and fitness characteristics (throwing velocity, vertical jump and hand grip strength). A Student’s t-test was used to determine whether a statistically significant difference between the two different levels of play occurred. Significant differences were found in age, body height, body mass, arm span, muscle mass, different girths (tensed and flexed arm, forearm, wrist, ankle), dominant hand width and length, different breadths (biacromial, bitrochanteric, bistyloid breadth and biepicondylar humerus) and fitness characteristics (hand grip strength and throwing velocity for different positions). Top elite players compared to elite players showed differences in anthropometric characteristics which were mainly located in the upper limbs and mostly were nonmodifiable aspects by training. Furthermore, the best players were able to maintain a high throwing velocity in different tactical situations

Mining of the Milky Way Star Archive Gaia-DR2: Searching for Binary Stars in Planetary Nebulae

This article belongs to the Proceedings of 3rd XoveTIC Conference[Abstract] The aim of this work is to search for binary stars associated to planetary nebulae (ionized stellar envelopes in expansion), by mining the astronomical archive of Gaia DR2, that is composed by around 1.7 billion stellar sources. For this task, we selected those objects with coincident astrometric parameters (parallaxes and proper motions) with the corresponding central star, among a sample of 211 planetary nebulae. By this method, we found eight binary systems, and we obtained their components positions, separations, temperatures and luminosities, as well as some of their masses and ages. In addition, we estimated the probability for each companion star of having been detected by chance and we analyzed how the number of false matches increase as the separation distance between both stars gets larger. All these procedures have been carried out making use of data mining techniques.Funding from Spanish Ministry projects ESP2016-80079-C2-2-R, RTI2018-095076-BC22, Xunta de Galicia ED431B 2018/42, and AYA-2017-88254-P is acknowledged by the authors. M.M. thanks the Instituto de Astrofísica de Canarias for a visiting stay funded by the Severo Ochoa Excellence programme. IGS acknowledges financial support from the Spanish National Programme for the Promotion of Talent and its Employability grant BES-2017-083126 cofunded by the European Social FundXunta de Galicia; ED431B 2018/4

Gaia DR2 Distances to Planetary Nebulae

[Abstract] The aim of this work is to examine distances to planetary nebulae (PNe) together with other properties that were derived from them, using the astrometry of Gaia Data Release 2 (DR2). We were able to identify 1571 objects classified as PNe, for which we assumed distances calculated following a Bayesian statistical approach. From those objects, we selected a sample of PNe with good quality parallax measurements and distance derivations, which we called Golden Astrometry PNe sample (GAPN). In this paper we will review the physical properties of the stars and nebulae in this subsample of PNe.Xunta de Galicia; ED431B 2018/42Funding from Spanish Ministry projects ESP2016-80079-C2-2-R, RTI2018-095076-BC22, Xunta de Galicia ED431B 2018/42, and AYA-2017-88254-P is acknowledged by the authors. M.M. thanks the Instituto de Astrofísica de Canarias for a visiting stay funded by the Severo Ochoa Excellence programme. IGS acknowledges financial support from the Spanish National Programme for the Promotion of Talent and its Employability grant BES-2017-083126 cofunded by the European Social Fun