The $UBV$ Color Evolution of Classical Novae. III. Time-Stretched Color-Magnitude Diagram of Novae in Outburst. (arXiv:1902.10919v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Hachisu_I/0/1/0/all/0/1">Izumi Hachisu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kato_M/0/1/0/all/0/1">Mariko Kato</a>
We propose a modified color-magnitude diagram for novae in outburst, i.e.,
$(B-V)_0$ versus $(M_V-2.5 log f_{rm s})$, where $f_{rm s}$ is the
timescaling factor of a (target) nova against a comparison (template) nova,
$(B-V)_0$ is the intrinsic $B-V$ color, and $M_V$ is the absolute $V$
magnitude. We dub it the time-stretched color-magnitude diagram. We carefully
reanalyzed 20 novae based on the time-stretching method and revised their
extinctions $E(B-V)$, distance moduli in the $V$ band $(m-M)_V$, distances $d$,
and timescaling factors $f_{rm s}$ against the template nova LV Vul. We have
found that these 20 nova outburst tracks broadly follow one of the two template
tracks, LV Vul/V1668 Cyg or V1500 Cyg/V1974 Cyg group, in the time-stretched
color-magnitude diagram. In addition, we estimate the white dwarf masses and
$(m-M)_V$ of the novae by directly fitting the absolute $V$ model light curves
($M_V$) with observational apparent $V$ magnitudes ($m_V$). A good agreement in
the two estimates of $(m-M)_V$ confirms the consistency of the time-stretched
color-magnitude diagram. Our distance estimates are in good agreement with the
results of Gaia Data Release 2.
We propose a modified color-magnitude diagram for novae in outburst, i.e.,
$(B-V)_0$ versus $(M_V-2.5 log f_{rm s})$, where $f_{rm s}$ is the
timescaling factor of a (target) nova against a comparison (template) nova,
$(B-V)_0$ is the intrinsic $B-V$ color, and $M_V$ is the absolute $V$
magnitude. We dub it the time-stretched color-magnitude diagram. We carefully
reanalyzed 20 novae based on the time-stretching method and revised their
extinctions $E(B-V)$, distance moduli in the $V$ band $(m-M)_V$, distances $d$,
and timescaling factors $f_{rm s}$ against the template nova LV Vul. We have
found that these 20 nova outburst tracks broadly follow one of the two template
tracks, LV Vul/V1668 Cyg or V1500 Cyg/V1974 Cyg group, in the time-stretched
color-magnitude diagram. In addition, we estimate the white dwarf masses and
$(m-M)_V$ of the novae by directly fitting the absolute $V$ model light curves
($M_V$) with observational apparent $V$ magnitudes ($m_V$). A good agreement in
the two estimates of $(m-M)_V$ confirms the consistency of the time-stretched
color-magnitude diagram. Our distance estimates are in good agreement with the
results of Gaia Data Release 2.
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