Browsing by Author "Gruberbauer, Michael"

Browsing by Author "Gruberbauer, Michael"

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    Observations of intensity fluctuations attributed to granulation and faculae on Sun-like stars from the Kepler mission 
    Gruberbauer, Michael; Karoff, C.; Campante, T. L.; Ballot, J.; Kallinger, T.; Garcia, R. A.; Caldwell, D. A.; Christiansen, J. L.; Kinemuchi, K. (American Astronomical Society, 2013-04-10)
    Sun-like stars show intensity fluctuations on a number of timescales due to various physical phenomena on their surfaces. These phenomena can convincingly be studied in the frequency spectra of these stars—while the strongest ...

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    On the detection of Lorentzian profiles in a power spectrum: a Bayesian approach using ignorance priors 
    Guenther, David B.; Gruberbauer, Michael; Kallinger, T.; Weiss, W. W. (EDP Sciences, 2009-11)
    Aims. Deriving accurate frequencies, amplitudes, and mode lifetimes from stochastically driven pulsation is challenging, more so, if one demands that realistic error estimates be given for all model fitting parameters. As ...

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    Oscillating red giants in the CoRoT exofield: asteroseismic mass and radius determination 
    Cameron, C.; Gruberbauer, Michael; Kallinger, T.; Weiss, W. W.; Barban, C.; Baudin, F.; Carrier, F.; De Ridder, J.; Goupil, M.-J.; Hatzes, A. (EDP Sciences, 2010-01)
    Context. Observations and analysis of solar-type oscillations in red-giant stars is an emerging aspect of asteroseismic analysis with a number of open questions yet to be explored. Although stochastic oscillations have ...

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    Oscillation mode frequencies of 61 main sequence and subgiant stars observed by Kepler 
    Appourchaux, T.; Chaplin, W. J.; Garcia, R. A.; Gruberbauer, Michael; Verner, G. A.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Deheuvels, S. (EDP Sciences, 2012)
    Context. Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars, thereby providing a way to probe the stars using asteroseismology. Aims. We provide the mode frequencies of the oscillations ...

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    Oscillation mode linewidths of main-sequence and subgiant stars observed by Kepler 
    Appourchaux, T.; Benomar, O.; Gruberbauer, Michael; Chaplin, W. J.; Garcia, R. A.; Handberg, R.; Verner, G. A.; Antia, H. M.; Campante, T. L.; Davies, G. R. (EDP Sciences, 2012-01)
    Context. Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars. Aims. We study the variations in the stellar p-mode linewidth as a function of effective temperature. Methods. We study ...

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    Properties of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal 
    Metcalfe, T. S.; Creevey, O. L.; Drogan, G.; Mathur, S.; Xu, H.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Karoff, C.; Trampedach, R.; Gruberbauer, Michael; Guenther, David B. (The American Astronomical Society, 2014-10)
    Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for ...

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    Pulsation analysis of V 588 MON AND V 589 MON observed with the MOST AND CoRoT satellites 
    Zwintz, K.; Kallinger, T.; Guenther, David B.; Gruberbauer, Michael; Kuschnig, R.; Weiss, W. W.; Auvergne, M.; Jorda, L.; Favata, F.; Matthews, J.; Fischer, M. (American Astronomical SocietyIOP Publishing, 2011-03-01)
    The two pulsating pre-main sequence (PMS) stars V 588 Mon and V 589 Mon were observed by CoRoT for 23.4 days in 2008 March during the Short Run SRa01 and in 2004 and 2006 by MOST for a total of ∼70 days. We present their ...

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    Pulsation models for the roAp star HD 134214 
    Saio, H.; Gruberbauer, Michael; Weiss, W. W.; Matthews, J. M.; Ryabchikova, T. (Oxford University Press, 2012-02)
    Precise time series photometry with the MOST satellite has led to identification of 10 pulsation frequencies in the rapidly oscillating Ap (roAp) star HD134214. We have fitted the observed frequencies with theoretical ...

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    A remarkable long-term light curve and deep, low-state spectroscopy: Swift and XMM-Newton monitoring of the NLS1 galaxy Mkn 335 
    Gallo, Luigi C.; Gruberbauer, Michael; Grupe, Dirk; Komossa, S.; Longinotti, Anna Lia; Fabian, Andrew C.; Pradhan, Anil K.; Xu, Dawei (American Astronomical Society, 2012-04)
    The narrow-line Seyfert 1 galaxy (NLS1) Mkn 335 is remarkable because it has repeatedly shown deep, long X-ray low states that show pronounced spectral structure. It has become one of the prototype active galactic nuclei ...

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    Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436 
    Gruberbauer, Michael; Balona, L. A.; Cunha, M. S.; Kurtz, D. W.; Saio, H.; White, T. R.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Christiansen, J. L.; Hall, J. R. (Oxford University Press, 2011)
    Photometry of KIC 10483436 was obtained continuously with 1-min exposures over a 27-d period from the Kepler satellite. The light curve shows rotational variations from surface spots with a period of 4.303 [plus or minus] ...

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    A search for p-modes and other variability in the binary system 85 Pegasi using MOST photometry 
    Guenther, David B.; Gruberbauer, Michael; Huber, D.; Matthews, J. M.; Croll, B.; Obbrugger, M.; Weiss, W. W.; Rowe, J. F.; Kallinger, T.; Kuschnig, R. (EDP Sciences, 2009-10)
    Context. Asteroseismology has great potential for the study of metal-poor stars due to its sensitivity to determine stellar ages. Solid detections of oscillation frequencies in stars with well constrained fundamental ...

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    Solar-like oscillations and activity in Procyon: A comparison of the 2007 MOST and ground-based radial velocity campaigns 
    Huber, Daniel; Bedding, Timothy R.; Arentoft, Torben; Gruberbauer, Michael; Guenther, David B.; Houdek, Gunter; Kallinger, Thomas; Kjeldsen, Hans; Matthews, Jaymie M.; Stello, Dennis; Weiss, Werner W. (American Astronomical SocietyIOP Publishing, 2011-04-20)
    We compare the simultaneous 2007 space-based MOST photometry and ground-based radial velocity (RV) observations of the F5 star Procyon. We identify slow variations in the MOST data that are similar to those reported in the ...

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    Solar-like oscillations in low-luminosity red giants: first results from Kepler 
    Gruberbauer, Michael; Bedding, T. R.; Huber, D.; Stello, D.; Elsworth, Y. P.; Hekker, S.; Kallinger, T.; Mathur, S.; Mosser, B.; Preston, H. L. (American Astronomical Society, 2010-04-20)
    We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30 minute sampling, reveal clear ...

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    Solving the mode identification problem in asteroseismology of F stars observed with Kepler 
    White, Timothy R.; Bedding, Timothy R.; Gruberbauer, Michael; Benomar, Othman; Stello, Dennis; Appourchaux, Thierry; Chaplin, William J.; Christensen-Dalsgaard, Jorgen; Elsworth, Yvonne P.; Garcia, Rafael A. (IOP Publishing Limited, 2012-06-01)
    Asteroseismology of F-type stars has been hindered by an ambiguity in identification of their oscillation modes. The regular mode pattern that makes this task trivial in cooler stars is masked by increased line widths. The ...

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    Sounding open clusters: asteroseismic constraints from Kepler on the properties of NGC 6791 and NGC 6819 
    Gruberbauer, Michael; Basu, Sarbani; Grundahl, Frank; Stello, Dennis; Kallinger, T.; Hekker, Saskia; Mosser, Benoit; Garcia, Rafael A.; Mathur, Savita; Brogaard, Karsten (American Astronomical Society, 2011-03-01)
    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 ...

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    Toward a new kind of asteroseismic grid fitting 
    Gruberbauer, Michael; Guenther, David B.; Kallinger, T. (American Astronomical Society, 2012-04-20)
    Recent developments in instrumentation (e.g., in particular the Kepler and CoRoT satellites) provide a new opportunity to improve the models of stellar pulsations. Surface layers, rotation, and magnetic fields imprint ...

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    Weak magnetic fields in Ap/Bp stars: evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy 
    Auriere, M.; Wade, G. A.; Silvester, J.; Lignieres, F.; Bagnulo, S.; Bale, K.; Dintrans, B.; Donati, J. F.; Folsom, C. P.; Gruberbauer, Michael; Toque, N. (EDP Sciences, 2007-12)
    Aims. We investigated a sample of 28 well-known spectroscopically-identified magnetic Ap/Bp stars, with weak, poorly-determined or previously undetected magnetic fields. The aim of this study is to explore the weak part ...