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Post Info TOPIC: Procyon A


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Posts: 128093
Date:
HD 61421
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Procyon captured with a 100mm f5 Helios achromatic refractor and Canon EOS 350.

Picture 816



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Posts: 128093
Date:
Alpha Canis Minoris
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Picture 817
Date: 30.01.17


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Posts: 128093
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RE: Procyon A
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Procyon (Alpha Canis Minoris, HD 61421) is a magnitude +0.34 binary star located 11.46 light-years away in the constellation Canis Minor.

Picture 692

RA: 07h 39m 18.11950s, Dec +05 13' 29.9552"



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Title: The Age and Stellar Parameters of the Procyon Binary System
Authors: James Liebert, Gilles Fontaine, Patrick A. Young, Kurtis A. Williams, David Arnett

The Procyon AB binary system (orbital period 40.838 years, a newly-refined determination), is near and bright enough that the component radii, effective temperatures, and luminosities are very well determined, although more than one possible solution to the masses has limited the claimed accuracy. Preliminary mass determinations for each component are available from HST imaging, supported by ground-based astrometry and an excellent Hipparcos parallax; we use these for our preferred solution for the binary system. Other values for the masses are also considered. We have employed the TYCHO stellar evolution code to match the radius and luminosity of the F5 IV-V primary star to determine the system's most likely age as 1.87 0.13 Gyr. Since prior studies of Procyon A found its abundance indistinguishable from solar, the solar composition of Asplund, Grevesse & Sauval (Z=0.014) is assumed for the HR Diagram flitting. An unsuccessful attempt to fit using the older solar abundance scale of Grevesse & Sauval (Z=0.019) is also reported. For Procyon B, eleven new sequences for the cooling of non-DA white dwarfs have been calculated, to investigate the dependence of the cooling age on (1) the mass, (2) the core composition, (3) the helium layer mass, and (4) heavy-element opacities in the helium envelope. Our calculations indicate a cooling age of 1.190.11 Gyr, which implies that the progenitor mass of Procyon B was 2.59(+0.44,-0.26) solar masses. In a plot of initial vs final mass of white dwarfs in astrometric binaries or star clusters (all with age determinations), the Procyon B final mass lies several sigma below a straight line fit.

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Posts: 128093
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Procyon
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Title: Solar-like oscillations and activity in Procyon: A comparison of the 2007 MOST and ground-based radial velocity campaigns
Authors: Daniel Huber, Timothy R. Bedding, Torben Arentoft, Michael Gruberbauer, David B. Guenther, Gnter Houdek, Thomas Kallinger, Hans Kjeldsen, Jaymie M. Matthews, Dennis Stello, Werner W. Weiss

We compare the simultaneous 2007 space-based MOST photometry and ground-based radial velocity observations of the F5 star Procyon. We identify slow variations in the MOST data that are similar to those reported in the radial velocity (RV) time series, and confirm by comparison with the Sun that these variations are likely the signature of stellar activity. The MOST power spectrum yields clear evidence for individual oscillation frequencies that match those found in the radial velocity data by Bedding et al. (2010). We identify the same ridges due to modes of different spherical degree in both datasets, but are not able to confirm a definite ridge identification using the MOST data. We measure the luminosity amplitude per radial mode A_{l=0, phot} = 9.1 0.5 ppm. Combined with the estimate for the RV data by Arentoft et al. (2008) this gives a mean amplitude ratio of A_{l=0, phot}/A_{l=0, RV} = 0.24 0.02 ppm cm^{-1} s, considerably higher than expected from scaling relations but in reasonable agreement with theoretical models by Houdek (2009). We also compare the amplitude ratio as a function of frequency, and find that the maximum of the oscillation envelope is shifted to higher frequencies in photometry than in velocity.

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RE: Procyon A
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Title: A multi-site campaign to measure solar-like oscillations in Procyon. I. Observations, Data Reduction and Slow Variations
Authors: Torben Arentoft, Hans Kjeldsen, Timothy R. Bedding, Michael Bazot, Joergen 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, Laszlo 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-Chieze, Milena Martic, Jean-Claude Lebrun, Jerome Schmitt, Jean-Loup Bertaux, Alfio Bonanno, Serena Benatti, Riccardo U. Claudi, Rosario Cosentino, Silvio Leccia, Soeren Frandsen, Karsten Brogaard, Lars Glowienka, et al. (2 additional authors not shown)
(Version v2)

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 organised 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 measurement uncertainties and adjusting them in order to minimise 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.

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Title: Asteroseismology of Procyon with SOPHIE
Authors: B. Mosser, F. Bouchy, M. Martic, et al

This paper reports a 9-night asteroseismic observation program conducted in January 2007 with the new spectrometer Sophie at the OHP 193-cm telescope, on the F5 IV-V target Procyon A. This first asteroseismic program with Sophie was intended to test the performance of the instrument with a bright but demanding asteroseismic target and was part of a multisite network. The Sophie spectra have been reduced with the data reduction software provided by OHP. The Procyon asteroseismic data were then analysed with statistical tools. The asymptotic analysis has been conducted considering possible curvature in the echelle diagram analysis. These observations have proven the efficient performance of Sophie used as an asteroseismometer, and succeed in a clear detection of the large spacing. An \'echelle diagram based on the 54-Hz spacing shows clear ridges. Identification of the peaks exhibits large spacings varying from about 52 Hz to 56 Hz.

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Title: Oscillations in Procyon A: First results from a multi-site campaign
Authors: S. Hekker, S. Reffert, T. R. Bedding, H. Bruntt, R. P. Butler, L. L. Kiss, S. J. O'Toole, E. Kambe, H. Ando, H. Izumiura, B. Sato, M. Hartmann, A. P. Hatzes, T. Appourchaux, C. Barban, G. Berthomieu, F. Bouchy, C. Catala, R. A. Garcia, J.-C. Lebrun, M. Martic, E. Michel, B. Mosser, P. A. P. Nghiem, J. Provost, R. Samadi, F. Thevenin, S. Turck-Chiez, S. A. Bonanno, S. Benatti, R. U. Claudi, R. Cosentino, S. Leccia, S. Frandsen, K. Brogaard, F. Grundahl, H. Kjeldsen, H. C. Stempels, T. Arentoft, M. Bazot, J. Christensen-Dalsgaard, T. H. Dall, F. Carrier, P. Eggenberger, D. Sosnowska, R. A. Wittenmyer, M. Endl, T. S. Metcalfe
(Version v2)

Procyon A is a bright F5IV star in a binary system. Although the distance, mass and angular diameter of this star are all known with high precision, the exact evolutionary state is still unclear. Evolutionary tracks with different ages and different mass fractions of hydrogen in the core pass, within the errors, through the observed position of Procyon A in the Hertzsprung-Russell diagram. For more than 15 years several different groups have studied the solar-like oscillations in Procyon A to determine its evolutionary state. Although several studies independently detected power excess in the periodogram, there is no agreement on the actual oscillation frequencies yet. This is probably due to either insufficient high-quality data (i.e. aliasing) or due to intrinsic properties of the star (i.e. short mode lifetimes). Now a spectroscopic multi-site campaign using 10 telescopes world-wide (minimising aliasing effects) with a total time span of nearly 4 weeks (increase the frequency resolution) is performed to identify frequencies in this star and finally determine its properties and evolutionary state.

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Posts: 128093
Date:
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Title: Oscillations in Procyon A: First results from a multi-site campaign
Authors: S Hekker, S Reffert, T R Bedding, H Bruntt, R P Butler, L L Kiss, S J O'Toole, E Kambe, H Ando, H Izumiura, B Sato, M Hartmann, A P Hatzes, T Appourchaux, C Barban, G Berthomieu, F Bouchy, C Catala, R A Garcia, J-C Lebrun, M Martic, E Michel, B Mosser, P A P Nghiem, J Provost, R Samadi, F Thevenin, S Turck-Chiez, S A Bonanno, S Benatti, R U Claudi, R Cosentino, S Leccia, S Frandsen, K Brogaard, F Grundahl, H Kjeldsen, H C Stempels, T Arentoft, M Bazot, J Christensen-Dalsgaard, T H Dall, F Carrier, P Eggenberger, D Sosnowska, R A Wittenmeyer, M Endl, T S Metcalfe

Procyon A is a bright F5IV star in a binary system. Although the distance, mass and angular diameter of this star are all known with high precision, the exact evolutionary state is still unclear. Evolutionary tracks with different ages and different mass fractions of hydrogen in the core pass, within the errors, through the observed position of Procyon A in the Hertzsprung-Russell diagram. For more than 15 years several different groups have studied the solar-like oscillations in Procyon A to determine its evolutionary state. Although several studies independently detected power excess in the periodogram, there is no agreement on the actual oscillation frequencies yet. This is probably due to either insufficient high-quality data (i.e. aliasing) or due to intrinsic properties of the star (i.e. short mode lifetimes). Now a spectroscopic multi-site campaign using 10 telescopes world-wide (minimising aliasing effects) with a total time span of nearly 4 weeks (increase the frequency resolution) is performed to identify frequencies in this star and finally determine its properties and evolutionary state.

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