J/ApJ/729/L10 KIC stars properties in NGC 6791 and NGC 6819 (Basu+, 2011)
Sounding open clusters: asteroseismic constraints from Kepler on the properties
of NGC 6791 and NGC 6819.
Basu S., Grundahl F., Stello D., Kallinger T., Hekker S., Mosser B.,
Garcia R.A., Mathur S., Brogaard K., Bruntt H., Chaplin W.J., Gai N.,
Elsworth Y., Esch L., Ballot J., Bedding T.R., Gruberbauer M., Huber D.,
Miglio A., Yildiz M., Kjeldsen H., Christensen-Dalsgaard J.,
Gilliland R.L., Fanelli M.M., Ibrahim K.A., Smith J.C.
<Astrophys. J., 729, L10 (2011)>
=2011ApJ...729L..10B 2011ApJ...729L..10B
ADC_Keywords: Clusters, open ; Stars, giant ; Stars, masses ; Stars, diameters ;
Effective temperatures
Keywords: open clusters and associations: individual (NGC 6819, NGC 6791) -
stars: fundamental parameters - stars: interiors - stars: oscillations
Abstract:
We present initial results on some of the properties of open clusters
NGC 6791 and NGC 6819 derived from asteroseismic data obtained by
NASA's Kepler mission. In addition to estimating the mass, radius, and
log g of stars on the red giant branch (RGB) of these clusters, we
estimate the distance to the clusters and their ages. Our
model-independent estimate of the distance modulus of NGC 6791 is
(m-M)0=13.11±0.06. We find (m-M)0=11.85±0.05 for NGC 6819. The
average mass of stars on the RGB of NGC 6791 is 1.20±0.01M☉,
while that of NGC 6819 is 1.68±0.03M☉. It should be noted that
we do not have data that cover the entire RGB and the actual mass will
be somewhat lower. We have determined model-dependent estimates of
ages of these clusters. We find ages between 6.8 and 8.6Gyr for NGC 6791,
however, most sets of models give ages around 7Gyr. We obtain ages
between 2 and 2.4Gyr for NGC 6819.
Description:
We studied 34 stars in NGC 6791 and 21 stars in NGC 6819. Only
confirmed members were selected (see Stello et al.
2010ApJ...713L.182S 2010ApJ...713L.182S, 2011ApJ...737L..10S 2011ApJ...737L..10S, 2011ApJ...739...13S 2011ApJ...739...13S).
We use Kepler observations made between 2009 May and 2009 December
(i.e., Q1-Q3 data) for this work.
In this work we used three different implementations of grid-based
methods -the Yale-Birmingham (YB) pipeline (Basu et al.
2010ApJ...710.1596B 2010ApJ...710.1596B; Gai et al. 2011ApJ...730...63G 2011ApJ...730...63G), a slightly
modified version of the RADIUS pipeline of Stello et al.
(2009ApJ...700.1589S 2009ApJ...700.1589S), and the Seismic Fundamental Parameter (SFP)
pipeline of Kallinger et al. (2010A&A...522A...1K 2010A&A...522A...1K).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 55 Properties of stars in NGC 6791 and NGC 6819
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/540/A143 : Oscillations of red giants observed by Kepler (Mosser+, 2012)
J/A+A/531/A124 : Visibilities of stellar oscillation modes (Ballot+, 2011)
J/A+A/525/A131 : Solar-like oscillations in Kepler red giants (Hekker+, 2011)
J/ApJ/718/L97 : Early asteroseismic results from Kepler (Van Grootel+, 2010)
J/AJ/138/159 : NGC 6819 stellar radial-velocity and photometry (Hole+, 2009)
J/A+A/506/465 : Solar-like oscillations in red giants (Hekker+, 2009)
J/AJ/133/1585 : Stromgren photometry in NGC 6791 (Anthony-Twarog+, 2007)
J/MNRAS/358/795 : Variable stars in NGC 6819 field (Street+, 2005)
J/AJ/129/656 : Infrared photometry of NGC 6791 (Carney+, 2005)
J/AJ/129/2856 : Variable stars in NGC 6791 (Mochejska+, 2005)
J/PASP/115/413 : BVI photometry in the open cluster NGC 6791 (Stetson+, 2003)
J/AJ/123/3460 : Low-amplitude variables in NGC 6791 (Mochejska+, 2002)
J/A+AS/114/1 : CCD UBVI photometry of NGC 6791 (Kaluzny+, 1995)
J/AJ/108/585 : UBVI photometry of NGC 6791 (Montgomery+, 1994)
J/MNRAS/243/492 : BV Photometry of NGC 6791. (Kaluzny 1990)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [NGC]
5- 8 I4 --- NGC Cluster NGC number (6791 or 6819)
10- 16 I7 --- KIC Kepler identification number
18- 21 I4 K Teff [4007/4843] Effective temperature
23- 28 F6.3 mag Vmag [12.6/15.8] V band magnitude (1)
30- 35 F6.3 uHz Dnu Large frequency separation
37- 41 F5.3 uHz e_Dnu Uncertainty in Dnu
43- 49 F7.3 uHz numax Frequency of maximum power
51- 55 F5.3 uHz e_numax Uncertainty in numax
57- 61 F5.2 Rsun Rad Estimated stellar radius
63- 66 F4.2 Rsun E_Rad Upper limit uncertainty in Rad
68- 71 F4.2 Rsun e_Rad Lower limit uncertainty in Rad
73- 76 F4.2 Msun Mass Estimated stellar mass
78- 81 F4.2 Msun E_Mass Upper limit uncertainty in Mass
83- 86 F4.2 Msun e_Mass Lower limit uncertainty in Mass
88- 92 F5.3 [cm/s2] log(g) Log of estimated stellar surface gravity
94- 98 F5.3 [cm/s2] E_log(g) Upper limit uncertainty in log(g)
100-104 F5.3 [cm/s2] e_log(g) Lower limit uncertainty in log(g)
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Note (1): Photometry data for NGC 6791 are from Stetson et al. (2003,
Cat. J/PASP/115/413) and for NGC 6819 from Hole et al. (2009,
Cat. J/AJ/138/159). See Figure 1.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-Sep-2012