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A Multisite Campaign to Measure Solar‐like Oscillations in Procyon. I. Observations, Data Reduction, and Slow Variations

Torben Arentoft, Hans Kjeldsen, Timothy R. Bedding, Michaël Bazot, Jørgen Christensen‐Dalsgaard, Thomas H. Dall, Christoffer Karoff, Fabien Carrier, Patrick Eggenberger, Danuta Sosnowska, Robert A. Wittenmyer, Michael Endl (+36 others)
2008 Astrophysical Journal  

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2008 accepted
arXiv:0807.3794v3 fatcat:sbuj4fouzrh5tjc662y4sgkyj4
2008 pre-print
arXiv:0807.3794v2 fatcat:x6nojewqrneovjf6ixblskxfvy
2008 pre-print
arXiv:0807.3794v1 fatcat:h4opda3pija2bi6quujx47ynpu
We have carried out a multi-site campaign to measure oscillations in the F5 star Procyon A. We obtained high-precision velocity observations over more than three weeks with eleven telescopes, with almost continuous coverage for the central ten days. This represents the most extensive campaign so far organized on any solar-type oscillator. We describe in detail the methods we used for processing and combining the data. These involved calculating weights for the velocity time series from the
more » ... rement uncertainties and adjusting them in order to minimize the noise level of the combined data. The time series of velocities for Procyon shows the clear signature of oscillations, with a plateau of excess power that is centred at 0.9 mHz and is broader than has been seen for other stars. The mean amplitude of the radial modes is 38.1 +/- 1.3 cm/s (2.0 times solar), which is consistent with previous detections from the ground and by the WIRE spacecraft, and also with the upper limit set by the MOST spacecraft. The variation of the amplitude during the observing campaign allows us to estimate the mode lifetime to be 1.5 d (+1.9/-0.8 d). We also find a slow variation in the radial velocity of Procyon, with good agreement between different telescopes. These variations are remarkably similar to those seen in the Sun, and we interpret them as being due to rotational modulation from active regions on the stellar surface. The variations appear to have a period of about 10 days, which presumably equals the stellar rotation period or, perhaps, half of it. The amount of power in these slow variations indicates that the fractional area of Procyon covered by active regions is slightly higher than for the Sun.
doi:10.1086/592040 fatcat:ekyg4rcqw5d7dhd2l2mtuwwph4
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Citation

Torben Arentoft, Hans Kjeldsen, Timothy R. Bedding, Michaël Bazot, Jørgen Christensen‐Dalsgaard, Thomas H. Dall, Christoffer Karoff, Fabien Carrier, Patrick Eggenberger, Danuta Sosnowska, Robert A. Wittenmyer, Michael Endl, Travis S. Metcalfe, Saskia Hekker, Sabine Reffert, R. Paul Butler, Hans Bruntt, László L. Kiss, Simon J. O'Toole, Eiji Kambe, Hiroyasu Ando, Hideyuki Izumiura, Bun'ei Sato, Michael Hartmann, Artie Hatzes, Francois Bouchy, Benoit Mosser, Thierry Appourchaux, Caroline Barban, Gabrielle Berthomieu, Rafael A. Garcia, Eric Michel, Janine Provost, Sylvaine Turck‐Chièze, Milena Martić, Jean‐Claude Lebrun, Jerome Schmitt, Jean‐Loup Bertaux, Alfio Bonanno, Serena Benatti, Riccardo U. Claudi, Rosario Cosentino, Silvio Leccia, Søren Frandsen, Karsten Brogaard, Lars Glowienka, Frank Grundahl, Eric Stempels. "A Multisite Campaign to Measure Solar‐like Oscillations in Procyon. I. Observations, Data Reduction, and Slow Variations." Astrophysical Journal 687.2 (2008) 1180-1190