J/A+A/540/A143 Oscillations of red giants observed by Kepler (Mosser+, 2012)
Probing the core structure and evolution of red giants using gravity-dominated
mixed modes observed with Kepler.
Mosser B., Goupil M.J., Belkacem K., Michel E., Stello D., Marques J.P.,
Elsworth Y., Barban C., Beck P.G., Bedding T.R., De Ridder J.,
Garcia R.A., Hekker S., Kallinger T., Samadi R., Stumpe M.C., Barclay T.,
Burke C.J.
<Astron. Astrophys. 540, A143 (2012)>
=2012A&A...540A.143M 2012A&A...540A.143M
ADC_Keywords: Stars, giant ; Spectroscopy
Keywords: stars: oscillations - stars: interiors - stars: evolution -
stars: late-type - methods: data analysis - asteroseismology
Abstract:
There are now more than 22 months of long-cadence data available for
thousands of red giants observed with the Kepler space mission.
Consequently, we are able to clearly resolve fine details in their
oscillation spectra and see many components of the mixed modes that
probe the stellar core.
We report for the first time a parametric fit to the pattern of the
l=1 mixed modes in red giants, which is a powerful tool to identify
gravity-dominated mixed modes. With these modes, which share the
characteristics of pressure and gravity modes, we are able to probe
directly the helium core and the surrounding shell where hydrogen is
burning.
Description:
Asymptotic mixed-modes parameters of the red giant oscillation spectra
shown in the paper. Dnu is the large separation. numax indicates the
central frequency of the oscillation power excess. DPi1 is the gravity
period spacing, e_DPi1 its uncertainty, assuming that εg is
fixed to 1/2. If Dpi1 changes too much along the mixed-mode spectrum,
DPi1b gives the second possible value. q is the coupling factor, e_q
its uncertainty. Mass and Rad are the asteroseismic estimates of the
stellar mass and radius from scaling relations, using Teff from the
Kepler Input Catalog (Brown et al. 2011, Cat. V/133). The division
between RGB and clump stars is derived from Fig. 3; the limit between
the primary and secondary clump stars is set at 1.8 solar mass.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 63 218 Characteristic parameters of the red giants
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler Input Catalog number
10- 15 F6.3 uHz Dnu Large separation Δν in microHerz
between consecutive radial orders
17- 21 F5.1 uHz numax Frequency of maximum oscillation signal
23- 28 F6.2 s DPi1 Gravity period spacing, ΔΠ1
30- 35 F6.2 s DPi1b ? Second possible value of gravity period
spacing when DPi1 changes too much along
the mixed-mode spectrum
37- 40 F4.2 s e_DPi1 ? rms uncertainty of DPi1
42- 45 F4.2 --- q [0/1] Coupling factor (1)
47- 50 F4.2 --- e_q rms uncertainty on q
52- 56 F5.2 Rsun Rad ?=0 Stellar radius in solar unit
58- 61 F4.2 Msun Mass ?=0 Stellar mass in solar unit
63 A1 --- ev Evolutionary status: C=red-clump, R=red-giant,
S=secondary-clump.
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Note (1): q=0 is equivalent to no coupling, and maximum coupling occurs for q=1.
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Acknowledgements:
Benoit Mosser, benoit.mosser(at)obspm.fr
(End) Benoit Mosser [Observatoire de Paris], Patricia Vannier [CDS] 12-Apr-2012