System parameters of three short period cataclysmic variable stars. (arXiv:2107.07400v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wild_J/0/1/0/all/0/1">J. F. Wild</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Littlefair_S/0/1/0/all/0/1">S. P. Littlefair</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ashley_R/0/1/0/all/0/1">R. P. Ashley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Breedt_E/0/1/0/all/0/1">E. Breedt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_A/0/1/0/all/0/1">A. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dhillon_V/0/1/0/all/0/1">V. S. Dhillon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dyer_M/0/1/0/all/0/1">M. J. Dyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Green_M/0/1/0/all/0/1">M. J. Green</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kerry_P/0/1/0/all/0/1">P. Kerry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marsh_T/0/1/0/all/0/1">T. R. Marsh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parsons_S/0/1/0/all/0/1">S. G. Parsons</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sahman_D/0/1/0/all/0/1">D. I. Sahman</a>
Using photometric ULTRACAM observations of three new short period cataclysmic
variables, we model the primary eclipse lightcurves to extract the orbital
separation, masses, and radii of their component stars. We find donor masses of
0.060 +/- 0.008 solar masses, 0.042 +/- 0.001 solar masses, and 0.042 +/- 0.004
solar masses, two being very low-mass sub-stellar donors, and one within 2
sigma of the hydrogen burning limit. All three of the new systems lie close to
the modified, “optimal” model evolutionary sequence of Knigge et al. (2011). We
briefly re-evaluate the long-standing discrepancy between observed donor mass
and radius data, and theoretical CV evolutionary tracks. By looking at the
difference in the observed period at each mass and the period predicted by the
Knigge et al. (2011) evolutionary sequence, we qualitatively examine the form
of excess angular momentum loss that is missing from the models below the
period gap. We show indications that the excess angular momentum loss missing
from CV models grows in importance relative to gravitational losses as the
period decreases. Detailed CV evolutionary models are necessary to draw more
quantitative conclusions in the future.
Using photometric ULTRACAM observations of three new short period cataclysmic
variables, we model the primary eclipse lightcurves to extract the orbital
separation, masses, and radii of their component stars. We find donor masses of
0.060 +/- 0.008 solar masses, 0.042 +/- 0.001 solar masses, and 0.042 +/- 0.004
solar masses, two being very low-mass sub-stellar donors, and one within 2
sigma of the hydrogen burning limit. All three of the new systems lie close to
the modified, “optimal” model evolutionary sequence of Knigge et al. (2011). We
briefly re-evaluate the long-standing discrepancy between observed donor mass
and radius data, and theoretical CV evolutionary tracks. By looking at the
difference in the observed period at each mass and the period predicted by the
Knigge et al. (2011) evolutionary sequence, we qualitatively examine the form
of excess angular momentum loss that is missing from the models below the
period gap. We show indications that the excess angular momentum loss missing
from CV models grows in importance relative to gravitational losses as the
period decreases. Detailed CV evolutionary models are necessary to draw more
quantitative conclusions in the future.
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