scholarly journals A homogeneous distance catalogue for Galactic RV Tauri objects

2016 ◽  
Vol 12 (S323) ◽  
pp. 371-372
Author(s):  
Shane B. Vickers ◽  
David J. Frew ◽  
Matt S. Owers ◽  
Quentin A. Parker ◽  
Ivan S. Bojičić

AbstractA subset of Post-AGB (PAGB) objects are the highly luminous RV Tauri variables that show similarities to Type-II Cepheids. By using a sample of known RV Tauri stars from the Magellanic Clouds we are able to determine period luminosity relationships (PLRs) in various bands that have been used to determine the luminosities of their Galactic counterparts. We have gathered all available photometry in order to generate an SED for each object and determine the total integrated flux. This total flux combined with a calculated or inferred intrinsic luminosity leads to a distance (Vickers et al. 2015). This distance catalogue has allowed us to begin to constrain the physical parameters of this poorly understood evolutionary phase and to determine links between these physical characteristics as a function of their stellar population.

2007 ◽  
Vol 3 (S248) ◽  
pp. 66-73
Author(s):  
J.-E. Arlot

AbstractThe main goal of the astrometry of solar system objects is to build dynamical models of their motions to understand their evolution, to determine physical parameters and to build accurate ephemerides for the preparation and the exploitation of space missions. For many objects, the ground-based observations are still very important because radar or observations from space probes are not available. More, the need of observations on a long period of time makes the ground-based observations necessary. The solar system objects have very different characteristics and the increase of the astrometric accuracy will depend on the objects and on their physical characteristics. The purpose of this communication is to show how to get the best astrometric accuracy.


2005 ◽  
Vol 192 ◽  
pp. 275-280 ◽  
Author(s):  
L. Zampieri ◽  
M. Ramina ◽  
A. Pastorello

SummaryWe present the results of a systematic analysis of a group of Type II plateau supernovae that span a large range in luminosities, from faint objects like SN 1997D and 1999br to very luminous events like SN 1992am. The physical properties of the supernovae appear to be related to the plateau luminosity or the expansion velocity. The simultaneous analysis of the observed light curves, line velocities and continuum temperatures leads us to robust estimates of the physical parameters of the ejected envelope. We find strong correlations among several parameters. The implications of these results regarding the nature of the progenitor, the central remnant and the Ni yield are also addressed.


2011 ◽  
Vol 413 (1) ◽  
pp. 223-234 ◽  
Author(s):  
Noriyuki Matsunaga ◽  
Michael W. Feast ◽  
Igor Soszyński
Keyword(s):  

2007 ◽  
Vol 3 (S245) ◽  
pp. 181-184
Author(s):  
Genevieve J. Graves

AbstractWe present recent results showing that a large fraction of red sequence galaxies contain ionized gas with LINER-like optical emission line ratios. This emission is more frequently found in galaxies with lower central velocity dispersion (σ) and these galaxies typically have younger mean ages than galaxies at the same σ which do not host emission. We suggest that the presence of LINER-like emission may be determined by the quantity of interstellar material in these galaxies and may be associated with the recent accretion of a gas-rich satellite galaxy or alternatively with stellar mass loss that declines as the galaxy stellar population ages.


2015 ◽  
Vol 11 (A29B) ◽  
pp. 276-277
Author(s):  
Hanindyo Kuncarayakti

AbstractIntegral field spectroscopy of nearby supernova sites within ~30 Mpc have been obtained using multiple IFU spectrographs in Hawaii and Chile. This technique enables both spatial and spectral information of the explosion sites to be acquired simultaneously, thus providing the identification of the parent stellar population of the supernova progenitor and the estimates for its physical parameters including age and metallicity via the spectrum. While this work has mainly been done in the optical wavelengths using instruments such as VIMOS, GMOS, and MUSE, a near-infrared approach has also been carried out using the AO-assisted SINFONI. By studying the supernova parent stellar population, we aim to characterize the mass and metallicity of the progenitors of different types of supernovae.


2019 ◽  
Vol 629 ◽  
pp. A124 ◽  
Author(s):  
Laureano Martinez ◽  
Melina C. Bersten

The detailed study of supernovae (SNe) and their progenitors allows a better understanding of the evolution of massive stars and how these end their lives. Despite its importance, the range of physical parameters for the most common type of explosion, the type II supernovae (SNe II), is still unknown. In particular, previous studies of type II-Plateau supernovae (SNe II-P) showed a discrepancy between the progenitor masses inferred from hydrodynamic models and those determined from the analysis of direct detections in archival images. Our goal is to derive physical parameters (progenitor mass, radius, explosion energy and total mass of nickel) through hydrodynamical modelling of light curves and expansion velocity evolution for a select group of six SNe II-P (SN 2004A, SN 2004et, SN 2005cs, SN 2008bk, SN 2012aw, and SN 2012ec) that fulfilled the following three criteria: (1) enough photometric and spectroscopic monitoring is available to allow for a reliable hydrodynamical modelling; (2) a direct progenitor detection has been achieved; and (3) there exists confirmation of the progenitor identification via its disappearance in post-explosion images. We then compare the masses obtained by our hydrodynamic models with those obtained by direct detections of the progenitors to test the existence of such a discrepancy. As opposed to some previous works, we find good agreement between both methods. We obtain a wide range in the physical parameters for our SN sample. We infer presupernova masses between 10 and 23 M⊙, progenitor radii between 400 and 1250 R⊙, explosion energies between 0.2 and 1.4 foe, and 56Ni masses between 0.0015 and 0.085 M⊙. An analysis of possible correlations between different explosion parameters is presented. The clearest relation found is that between the mass and the explosion energy, in the sense that more-massive objects produce higher-energy explosions, in agreement with previous studies. Finally, we also compare our results with previous physical–observed parameter relations widely used in the literature. We find significant differences between both methods, which indicates that caution should be exercised when using these relations.


2008 ◽  
Vol 4 (S256) ◽  
pp. 20-29 ◽  
Author(s):  
Yaël Nazé

AbstractIn the study of stars, the high energy domain occupies a place of choice, since it is the only one able to directly probe the most violent phenomena: indeed, young pre-main sequence objects, hot massive stars, or X-ray binaries are best revealed in X-rays. However, previously available X-ray observatories often provided only crude information on individual objects in the Magellanic Clouds. The advent of the highly efficient X-ray facilities XMM-Newton and Chandra has now dramatically increased the sensitivity and the spatial resolution available to X-ray astronomers, thus enabling a fairly easy determination of the properties of individual sources in the LMC.


1999 ◽  
Vol 192 ◽  
pp. 100-103
Author(s):  
A. P. Cowley ◽  
P. C. Schmidtke ◽  
V. A. Taylor ◽  
T.K. McGrath ◽  
J. B. Hutchings ◽  
...  

In this study we compare the global populations of stellar X-ray sources in the LMC, SMC, and the Galaxy. After removing foreground stars and background AGN from the samples, the relative numbers of the various types of X-ray point sources within the LMC and SMC are similar, but differ markedly from those in the Galaxy. The Magellanic Clouds are rich in high-mass X-ray binaries (HMXB), especially those containing rapidly rotating Be stars. However, the LMC and SMC both lack the large number of low-mass X-ray binaries (LMXB) found in the Milky Way, which are known to represent a very old stellar population based on their kinematics, chemical composition, and spatial distribution.


2014 ◽  
Vol 10 (S312) ◽  
pp. 201-202 ◽  
Author(s):  
Zhou Fan ◽  
Yanbin Yang

AbstractThe recent studies show that the formation and evolution process of the nearby galaxies are still unclear. By using the Canada France Hawaii Telescope (CFHT) 3.6m telescope, the PanDAS shows complicated substructures (dwarf satellite galaxies, halo globular clusters, extended clusters, star streams, etc.) in the halo of M31 to ~150 kpc from the center of galaxy and M31-M33 interaction has been studied. In our work, we would like to investigate formation, evolution and interaction of M31 and M33, which are the nearest two spiral galaxies in Local Group. The star cluster systems of the two galaxies are good tracers to study the dynamics of the substructures and the interaction. Since 2010, the Xinglong 2.16m, Lijiang 2.4m and MMT 6.5m telescopes have been used for our spectroscopic observations. The radial velocities and Lick absorption-line indices can thus be measured with the spectroscopy and then ages, metallicities and masses of the star clusters can be fitted with the simple stellar population models. These parameters could be used as the input physical parameters for numerical simulations of M31-M33 interaction.


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