Predicting Granulation “Flicker” and Radial Velocity “Jitter” from Spectroscopic Observables. (arXiv:1812.04010v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tayar_J/0/1/0/all/0/1">Jamie Tayar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stassun_K/0/1/0/all/0/1">Keivan G. Stassun</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Corsaro_E/0/1/0/all/0/1">Enrico Corsaro</a>
Surface granulation can be predicted with the mass, metallicity, and
frequency of maximum power of a star. Using the orders-of-magnitude larger
APOGEE-Kepler sample, we recalibrate the relationship fit by Corsaro et al.
(2017) for “flicker”, an easier-to-compute diagnostic of this granulation. We
find that the relationship between the stellar parameters and flicker is
significantly different for dwarf and subgiant stars than it is for red giants.
We also confirm a dependence of flicker amplitude on metallicity as seen
originally by Corsaro et al. (2017), although the dependence found here is
somewhat weaker. Using the same APOGEE-Kepler sample, we demonstrate that
spectroscopic measurements alone provide sufficient information to estimate the
flicker amplitude to 7 percent for giants, and 20 percent for dwarfs and
subgiants. We provide a relationship that depends on effective temperature,
surface gravity, and metallicity, and calculate predicted flicker values for
129,000 stars with APOGEE spectra. Finally, we use published relationships
between flicker and radial velocity jitter to estimate minimum jitter values
for these same 129,000 stars, and we identify stars whose total jitter is
likely to be even larger than the granulation-driven jitter by virtue of
large-amplitude photometric variability.
Surface granulation can be predicted with the mass, metallicity, and
frequency of maximum power of a star. Using the orders-of-magnitude larger
APOGEE-Kepler sample, we recalibrate the relationship fit by Corsaro et al.
(2017) for “flicker”, an easier-to-compute diagnostic of this granulation. We
find that the relationship between the stellar parameters and flicker is
significantly different for dwarf and subgiant stars than it is for red giants.
We also confirm a dependence of flicker amplitude on metallicity as seen
originally by Corsaro et al. (2017), although the dependence found here is
somewhat weaker. Using the same APOGEE-Kepler sample, we demonstrate that
spectroscopic measurements alone provide sufficient information to estimate the
flicker amplitude to 7 percent for giants, and 20 percent for dwarfs and
subgiants. We provide a relationship that depends on effective temperature,
surface gravity, and metallicity, and calculate predicted flicker values for
129,000 stars with APOGEE spectra. Finally, we use published relationships
between flicker and radial velocity jitter to estimate minimum jitter values
for these same 129,000 stars, and we identify stars whose total jitter is
likely to be even larger than the granulation-driven jitter by virtue of
large-amplitude photometric variability.
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