Monthly Notices of The Royal Astronomical Society, 2011
Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 an... more Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 and 2010 in the Taurus and Lupus star formation regions are presented. Using light-curve modelling under the assumption of internal invariability of spots, we obtained small values of the solar-type differential-rotation parameter (k = 0.0005-0.009) for three spotted weak-line T Tauri stars, V410 Tau, V987 Tau
MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars... more MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars from space, as well as to study micro-variability in Wolf-Rayet winds and other targets. We give a brief technical description of the satellite as well as estimates on the expected photometric performance.
Light Curve Modeling of Eclipsing Binary Stars, 1993
ABSTRACT The authors discuss the evolution of the program LIGHT2 and its limitations. In addition... more ABSTRACT The authors discuss the evolution of the program LIGHT2 and its limitations. In addition they indicate areas that they deem important for future improvements.
... N. WINN 1, JAYMIE M. MATTHEWS 2, REBEKAH I. DAWSON 3 , DANIEL FABRYCKY 4,5 ,MATTHEW J. HOLMAN... more ... N. WINN 1, JAYMIE M. MATTHEWS 2, REBEKAH I. DAWSON 3 , DANIEL FABRYCKY 4,5 ,MATTHEW J. HOLMAN 3, THOMAS KALLINGER 2,6, RAINER KUSCHNIG 6, DIMITAR SASSELOV 3, DIANA DRAGOMIR 5, DAVID B. GUENTHER 7, ANTHONY FJ MOFFAT 8 , JASON ...
Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented... more Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the seventh set of ten close binary systems: V410 Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD 93917, NSV 223. All systems, but three (V523 Cas, HD 93917, NSV 223), were discovered photometrically by the Hipparcos mission. All systems
Monthly Notices of The Royal Astronomical Society, 2007
Highly precise and nearly uninterrupted optical photometry of the RR Lyrae star AQ Leo was obtain... more Highly precise and nearly uninterrupted optical photometry of the RR Lyrae star AQ Leo was obtained with the MOST (Microvariability & Oscillations of STars) satellite over 34.4 days in February-March 2005. AQ Leo was the first known double-mode RR Lyrae pulsator (RRd star). Three decades after its discovery, MOST observations have revealed that AQ Leo oscillates with at least 42
(abridged) There is considerable interest in the possible interaction between parent stars and gi... more (abridged) There is considerable interest in the possible interaction between parent stars and giant planetary companions in 51 Peg-type systems. We demonstrate from MOST satellite photometry and Ca II K line emission that there has been a persistent, variable region on the surface of tau Boo A which tracked its giant planetary companion for some 440 planetary revolutions and lies ~68deg (phi=0.8) in advance of the sub-planetary point. The light curves are folded on a range of periods centered on the planetary orbital period and phase dependent variability is quantified by Fourier methods and by the mean absolute deviation (MAD) of the folded data for both the photometry and the Ca II K line reversals. The region varies in brightness on the time scale of a rotation by ~1 mmag. In 2004 it resembled a dark spot of variable depth, while in 2005 it varied between bright and dark. Over the 123 planetary orbits spanned by the photometry the variable region detected in 2004 and in 2005 are synchronised to the planetary orbital period within 0.0015 d. The Ca II K line in 2001, 2002 and 2003 also shows enhanced K-line variability centered on phi=0.8, extending coverage to some 440 planetary revolutions. The apparently constant rotation period of the variable region and its rapid variation make an explanation in terms of conventional star spots unlikely. The lack of complementary variability at phi=0.3 and the detection of the variable region so far in advance of the sub-planetary point excludes tidal excitation, but the combined photometric and Ca II K line reversal results make a good case for an active region induced magnetically on the surface of tau Boo A by its planetary companion.
Monthly Notices of The Royal Astronomical Society, 2008
We present two series of MOST (Microvariability and Oscillations of STars) space-based photometry... more We present two series of MOST (Microvariability and Oscillations of STars) space-based photometry, covering nearly continuously 10 d in 2004 and 30 d in 2007, of selected variable stars in the upper main sequence of the old open cluster M67. New high-precision light curves were obtained for the blue straggler binary/triple systems AH Cnc, ES Cnc and EV Cnc. The precision and phase coverage of ES Cnc and EV Cnc is by far superior to any previous observations. The light curve of ES Cnc is modelled in detail, assuming two dark photospheric spots and Roche geometry. An analysis of the light curve of AH Cnc indicates a low mass ratio (q ~ 0.13) and a high inclination angle for this system. Two new long-period eclipsing binaries, GSC 814-323 and HD 75638 (non-members of M67) were discovered. We also present ground-based DDO spectroscopy of ES Cnc and of the newly found eclipsing binaries. Especially interesting is HD 75638, a member of a visual binary, which must itself be a triple or a h...
This volume contains the proceedings of the conference, Close Binary Stars in the 21st Century: N... more This volume contains the proceedings of the conference, Close Binary Stars in the 21st Century: New Opportunities and Challenges, held during 27–30 June, 2005 on Syros, Greece. The conference was attended by 107 participants from 31 countries from all over the world. The rapid advances and discoveries that have taken place over the last decade in the field of binary stars motivated this conference. The focus on binary and multiple star systems is important because surveys of stars in the Galaxy consistently show that most stars (over ∼60 percent) are members of binary and multiple star systems. Because most of the luminous matter in galaxies consists of stars, most of which are binary systems, it is crucial to determine the properties of these binary systems so that we can better understand the galaxies whose luminous matter consists mostly of these stars. Moreover, the evolution of binary stars is also responsible for large number of astrophysically diverse and energetic phenomena that include x-ray binaries (with black hole or neutron star components), cataclysmic variables and novae (with white dwarf components), and some types of supernovae (e g. -SN Is).
MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars... more MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars from space, as well as to study micro-variability in Wolf-Rayet winds and other targets. We give a brief technical description of the satellite as well as estimates on the expected photometric performance.
Monthly Notices of The Royal Astronomical Society, 2011
Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 an... more Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 and 2010 in the Taurus and Lupus star formation regions are presented. Using light-curve modelling under the assumption of internal invariability of spots, we obtained small values of the solar-type differential-rotation parameter (k = 0.0005-0.009) for three spotted weak-line T Tauri stars, V410 Tau, V987 Tau
MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars... more MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars from space, as well as to study micro-variability in Wolf-Rayet winds and other targets. We give a brief technical description of the satellite as well as estimates on the expected photometric performance.
Light Curve Modeling of Eclipsing Binary Stars, 1993
ABSTRACT The authors discuss the evolution of the program LIGHT2 and its limitations. In addition... more ABSTRACT The authors discuss the evolution of the program LIGHT2 and its limitations. In addition they indicate areas that they deem important for future improvements.
... N. WINN 1, JAYMIE M. MATTHEWS 2, REBEKAH I. DAWSON 3 , DANIEL FABRYCKY 4,5 ,MATTHEW J. HOLMAN... more ... N. WINN 1, JAYMIE M. MATTHEWS 2, REBEKAH I. DAWSON 3 , DANIEL FABRYCKY 4,5 ,MATTHEW J. HOLMAN 3, THOMAS KALLINGER 2,6, RAINER KUSCHNIG 6, DIMITAR SASSELOV 3, DIANA DRAGOMIR 5, DAVID B. GUENTHER 7, ANTHONY FJ MOFFAT 8 , JASON ...
Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented... more Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the seventh set of ten close binary systems: V410 Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD 93917, NSV 223. All systems, but three (V523 Cas, HD 93917, NSV 223), were discovered photometrically by the Hipparcos mission. All systems
Monthly Notices of The Royal Astronomical Society, 2007
Highly precise and nearly uninterrupted optical photometry of the RR Lyrae star AQ Leo was obtain... more Highly precise and nearly uninterrupted optical photometry of the RR Lyrae star AQ Leo was obtained with the MOST (Microvariability & Oscillations of STars) satellite over 34.4 days in February-March 2005. AQ Leo was the first known double-mode RR Lyrae pulsator (RRd star). Three decades after its discovery, MOST observations have revealed that AQ Leo oscillates with at least 42
(abridged) There is considerable interest in the possible interaction between parent stars and gi... more (abridged) There is considerable interest in the possible interaction between parent stars and giant planetary companions in 51 Peg-type systems. We demonstrate from MOST satellite photometry and Ca II K line emission that there has been a persistent, variable region on the surface of tau Boo A which tracked its giant planetary companion for some 440 planetary revolutions and lies ~68deg (phi=0.8) in advance of the sub-planetary point. The light curves are folded on a range of periods centered on the planetary orbital period and phase dependent variability is quantified by Fourier methods and by the mean absolute deviation (MAD) of the folded data for both the photometry and the Ca II K line reversals. The region varies in brightness on the time scale of a rotation by ~1 mmag. In 2004 it resembled a dark spot of variable depth, while in 2005 it varied between bright and dark. Over the 123 planetary orbits spanned by the photometry the variable region detected in 2004 and in 2005 are synchronised to the planetary orbital period within 0.0015 d. The Ca II K line in 2001, 2002 and 2003 also shows enhanced K-line variability centered on phi=0.8, extending coverage to some 440 planetary revolutions. The apparently constant rotation period of the variable region and its rapid variation make an explanation in terms of conventional star spots unlikely. The lack of complementary variability at phi=0.3 and the detection of the variable region so far in advance of the sub-planetary point excludes tidal excitation, but the combined photometric and Ca II K line reversal results make a good case for an active region induced magnetically on the surface of tau Boo A by its planetary companion.
Monthly Notices of The Royal Astronomical Society, 2008
We present two series of MOST (Microvariability and Oscillations of STars) space-based photometry... more We present two series of MOST (Microvariability and Oscillations of STars) space-based photometry, covering nearly continuously 10 d in 2004 and 30 d in 2007, of selected variable stars in the upper main sequence of the old open cluster M67. New high-precision light curves were obtained for the blue straggler binary/triple systems AH Cnc, ES Cnc and EV Cnc. The precision and phase coverage of ES Cnc and EV Cnc is by far superior to any previous observations. The light curve of ES Cnc is modelled in detail, assuming two dark photospheric spots and Roche geometry. An analysis of the light curve of AH Cnc indicates a low mass ratio (q ~ 0.13) and a high inclination angle for this system. Two new long-period eclipsing binaries, GSC 814-323 and HD 75638 (non-members of M67) were discovered. We also present ground-based DDO spectroscopy of ES Cnc and of the newly found eclipsing binaries. Especially interesting is HD 75638, a member of a visual binary, which must itself be a triple or a h...
This volume contains the proceedings of the conference, Close Binary Stars in the 21st Century: N... more This volume contains the proceedings of the conference, Close Binary Stars in the 21st Century: New Opportunities and Challenges, held during 27–30 June, 2005 on Syros, Greece. The conference was attended by 107 participants from 31 countries from all over the world. The rapid advances and discoveries that have taken place over the last decade in the field of binary stars motivated this conference. The focus on binary and multiple star systems is important because surveys of stars in the Galaxy consistently show that most stars (over ∼60 percent) are members of binary and multiple star systems. Because most of the luminous matter in galaxies consists of stars, most of which are binary systems, it is crucial to determine the properties of these binary systems so that we can better understand the galaxies whose luminous matter consists mostly of these stars. Moreover, the evolution of binary stars is also responsible for large number of astrophysically diverse and energetic phenomena that include x-ray binaries (with black hole or neutron star components), cataclysmic variables and novae (with white dwarf components), and some types of supernovae (e g. -SN Is).
MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars... more MOST is a Canadian micro-satellite project to perform seismology of solar-type and magnetic stars from space, as well as to study micro-variability in Wolf-Rayet winds and other targets. We give a brief technical description of the satellite as well as estimates on the expected photometric performance.
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