J/MNRAS/488/572 Bayesian hierarchical inferred inclinations (Kuszlewicz+, 2019)
Bayesian hierarchical inference of asteroseismic inclination angles.
Kuszlewicz J.S., Chaplin W.J., North T.S.H., Farr W.M., Bell K.J.,
Davies G.R., Campante T.L., Hekker S.
<Mon. Not. R. Astron. Soc., 488, 572-589 (2019)>
=2019MNRAS.488..572K 2019MNRAS.488..572K (SIMBAD/NED BibCode)
ADC_Keywords: Asteroseismology ; Stars, giant ; Models ; Optical
Keywords: asteroseismology, methods: data analysis, methods: statistical
Abstract:
The stellar inclination angle - the angle between the rotation axis of
a star and our line of sight - provides valuable information in many
different areas, from the characterization of the geometry of
exoplanetary and eclipsing binary systems to the formation and
evolution of those systems. We propose a method based on
asteroseismology and a Bayesian hierarchical scheme for extracting the
inclination angle of a single star. This hierarchical method therefore
provides a means to both accurately and robustly extract inclination
angles from red giant stars. We successfully apply this technique to
an artificial data set with an underlying isotropic inclination angle
distribution to verify the method. We also apply this technique to 123
red giant stars observed with Kepler. We also show the need for a
selection function to account for possible population-level biases,
which are not present in individual star-by-star cases, in order to
extend the hierarchical method towards inferring underlying population
inclination angle distributions.
Description:
Long-cadence data from the Kepler mission are used (a cadence of
29.4min) with all 4yr of observations from quarters Q1-Q17. Our sample
consists of 123 stars taken from the 13000 red giants in Stello et al.
(2013ApJ...765L..41S 2013ApJ...765L..41S, Cat. J/ApJ/765/L41) with a νmax (determined
by Stello et al. 2013ApJ...765L..41S 2013ApJ...765L..41S, Cat. J/ApJ/765/L41) in the range
231-274µHz. This νmax range was chosen because the probability
of a star possessing overlapping modes (due to rapid rotation) is very
low therefore making the identification of the mixed modes (those with
a mixed p- and g-character, see e.g. Mosser et al.
2014A&A...572L...5M 2014A&A...572L...5M, Cat. J/A+A/572/L5) easier. All photometric
timeseries were produced using the pipeline developed by Jenkins et
al. (2010ApJ...713L.120J 2010ApJ...713L.120J), and power spectra were obtained using the
Lomb-Scargle periodogram (Lomb 1976Ap&SS..39..447L 1976Ap&SS..39..447L; Scargle
1982ApJ...263..835S 1982ApJ...263..835S).
Due to the complexity of red giant oscillation spectra, not all of the
123 red giants in our sample could be used in the analysis. A few were
observed to show suppressed l=1 modes, which greatly hinder our
ability to extract the inclination angle. There were also some cases
where the stars had oscillation modes reflected from across the
Nyquist frequency (Chaplin et al. 2014MNRAS.445..946C 2014MNRAS.445..946C). Finally, there
were also a few stars for which the modes could not be successfully
disentangled with the current method due to the highly complex
spectra. The inferred inclination angles for 89 Kepler red giants are
given in Table F1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablef1.dat 26 89 Derived inclination angles for the stars in the
real sample
--------------------------------------------------------------------------------
See also:
J/ApJ/765/L41 : Asteroseismic classification of KIC objects (Stello+, 2013)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: tablef1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- KIC [2158352/12203197] Star name from KIC
10- 14 F5.2 deg i Incliation angle (1)
16- 20 F5.2 deg E_i Upper error on i
22- 26 F5.2 deg e_i Lower error on i
--------------------------------------------------------------------------------
Note (1): Inclination angles are infered by combining asteroseismic estimates
of the inclination angle of individual oscillation modes using a
hierarchical Bayesian method (See section 4 for details)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 24-Nov-2022