The properties of post-novae
Fecha
2022-03
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Universidad de Valparaíso
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Instituto de Fisica y Astronomia
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Resumen
The impact of nova eruptions on the long-term evolution of Cataclysmic Variables (CVs) is one of the least understood and intensively discussed topics in the field. A decisive ingredient to improve this would be to establish a large sample of post-novae with known properties. Novae are objects that are well studied in the maximum stage, but after the eruption a significant amount of time on large telescopes is needed to study them, due to them mostly turning into very faint objects.
In order to obtain a significant sample of post-novae, Tappert et al. started a project to enlarge the sample since 2009, called “Life after eruption”. This thesis is the direct continuation of their project, which is based on observations both photometric and spectroscopically using a variety of telescopes located in Chile. The steps to recover post-novae consist of (i) identifying post-nova candidates in the field through color-color diagrams (ii) confirming them through their spectral characteristics and (iii) if possible, obtaining the orbital period through time-series data either photometrically or spectroscopically, with the ultimate goal to obtain a significant and reliable sample in order to update some general aspects of the post-nova population, such as the orbital period distribution and their spectral characteristics.
In this work, we present the spectroscopic confirmation for eleven post-novae. Collecting spec- troscopic parameters from the literature including these new data, we present an updated spectral study of the post-novae. With all data from the “Life after eruption” project the observational lack of objects that erupted more than 60 years ago is significant filled. The main result points to there being no correlation between the mass transfer rate and the time since eruption, in good agree- ment with previous studies. The interpretation that strong equivalent widths would be indicators of low-mass transfer rate is not entirely correct (e.g. Patterson 1984), because they appear to be indicators of inclination rather than of the mass transfer rate. A more conclusive result for the behavior of the mass transfer can only be obtained with a larger sample of novae erupted especially more than 100 years ago.
We also present an updated orbital period distribution of novae using the new orbital periods found here, identifying the false-claims ones in the literature and stated reasons why they are not reliable. We compare the observational data with a theoretical period distribution calculated using both an empirical and the classical recipe for angular momentum loss. We find that neither model reproduces the observed peak in the 3 – 4 h range, suggesting that the prescription for magnetic braking usually used in CV evolution above the period gap is not totally understood.
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CONICYT-PFCHA Doctorado Nacional 2017-21171099
Palabras clave
ESTRELLAS VARIABLES CATACLISMICAS, NOVAS