Now showing items 1-20 of 29

  • Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237 

    Alvarado-Gómez, J.D.; Hussain, Gaitee Ara Jaffer; Grunhut, J.; Fares, Rim; Donati, J.-F.; Alecian, E.; Kochukhov, O.; Oksala, M.; Morin, J.; Redfield, S.; Cohen, O.; Drake, J.J.; Jardine, Moira Mary; Matt, S.; Petit, P.; Walter, F.M. (2015-10) - Journal article
    We analyse the magnetic activity characteristics of the planet-hosting Sun-like star, HD 1237, using HARPS spectro-polarimetric time-series data. We find evidence of rotational modulation of the magnetic longitudinal field ...
  • The connection between stellar activity cycles and magnetic field topology 

    See, V.; Jardine, M.; Vidotto, A. A.; Donati, J.-F.; Boro Saikia, S.; Bouvier, J.; Fares, R.; Folsom, C. P.; Gregory, S. G.; Hussain, G.; Jeffers, S. V.; Marsden, S. C.; Morin, J.; Moutou, C.; do Nascimento Jr., J. D.; Petit, P.; Waite, I. A. (2016-11-11) - Journal article
    Zeeman–Doppler imaging (ZDI) has successfully mapped the large-scale magnetic fields of stars over a large range of spectral types, rotation periods and ages. When observed over multiple epochs, some stars show polarity ...
  • A coordinated optical and X-ray spectroscopic campaign on HD 179949 : searching for planet-induced chromospheric and coronal activity 

    Scandariato, G.; Maggio, A.; Lanza, A. F.; Pagano, I.; Fares, R.; Shkolnik, E. L.; Bohlender, D.; Cameron, A. C.; Dieters, S.; Donati, J.-F.; Martínez Fiorenzano, A. F.; Jardine, M.; Moutou, C. (2013-04) - Journal article
    Context. HD 179949 is an F8V star, orbited by a close-in giant planet with a period of ~3 days. Previous studies suggested that the planet enhances the magnetic activity of the parent star, producing a chromospheric hot ...
  • Could a change in magnetic field geometry cause the break in the wind-activity relation? 

    Vidotto, Aline; Donati, J.-F.; Jardine, Moira Mary; See, Wyke Chun Victor; Petit, P.; Boisse, I.; Boro Saikia, S.; Hébrard, E.; Jeffers, Sandra Victoria; Marsden, S. C.; Morin, J. (2016-01-01) - Journal article
    Wood et al. suggested that mass-loss rate is a function of X-ray flux (dot{M}∝ F_x^{1.34}) for dwarf stars with Fx ≲ Fx,6 ≡ 106 erg cm-2 s-1. However, more active stars do not obey this relation. These authors suggested ...
  • Discovery and observations of ASASSN-13db, an EX lupi-type accretion event on a low-mass T tauri star 

    Holoien, T.W.-S.; Prieto, J.L.; Stanek, K.Z.; Kochanek, C.S.; Shappee, B.J.; Zhu, Z.; Sicilia-Aguilar, A.; Grupe, D.; Croxall, K.; Adams, J.J.; Simon, J.D.; Morrell, N.; McGraw, S.M.; Wagner, R.M.; Basu, U.; Beacom, J.F.; Bersier, D.; Brimacombe, J.; Jencson, J.; Pojmanski, G.; Starrfield, S.G.; Szczygieł, D.M.; Woodward, C.E. (2014-04-20) - Journal article
    We discuss ASASSN-13db, an EX Lupi-type ("EXor") accretion event on the young stellar object (YSO) SDSS J051011.01-032826.2 (hereafter SDSSJ0510) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). Using ...
  • Distribution and evolution of starspots on the RS CVn binary II Pegasi in 2004 

    Xiang, Y.; Gu, S.-H.; Collier Cameron, A.; Barnes, J.R. (2014-03-01) - Journal article
    We present Doppler images of RS CVn-type binary II Peg based on two data sets obtained in 2004 February and November. In order to improve signal-to-noise ratio and reliability,we apply least-squares deconvolution technique ...
  • Doppler images of the eclipsing binary ER Vulpeculae 

    Xiang, Y.; Gu, S.; Collier Cameron, A.; Barnes, J.R. (2015-02-11) - Journal article
    We present Doppler images of both components of the eclipsing binary system ER Vul, based on the spectra obtained in 2004 November, 2006 September and 2008 November. The least-squares deconvolution technique is used for ...
  • The energy budget of stellar magnetic fields 

    See, Wyke Chun Victor; Jardine, Moira Mary; Vidotto, Aline; Donati, J.-F.; Folsom, C. P.; Boro Saikia, S.; Bouvier, J.; Fares, Rim; Gregory, Scott; Hussain, Gaitee Ara Jaffer; Jeffers, Sandra Victoria; Marsden, S. C.; Morin, J.; Moutou, C.; do Nascimento, J. D.; Petit, P.; Rosén, L.; Waite, I. A. (2015-11-11) - Journal article
    Spectropolarimetric observations have been used to map stellar magnetic fields, many of which display strong bands of azimuthal fields that are toroidal. A number of explanations have been proposed to explain how such ...
  • The energy budget of stellar magnetic fields : comparing non-potential simulations and observations 

    Lehmann, L. T.; Jardine, M. M.; Vidotto, A. A.; Mackay, D. H.; See, V.; Donati, J.-F.; Folsom, C. P.; Jeffers, S. V.; Marsden, S. C.; Morin, J.; Petit, P. (2016-10-27) - Journal article
    The magnetic geometry of the surface magnetic fields of more than 55 cool stars have now been mapped using spectropolarimetry. In order to better understand these observations, we compare the magnetic fieldt opology at ...
  • The energy budget of stellar magnetic fields : comparing non-potential simulations and observations 

    Lehmann, L. T.; Jardine, M. M.; Vidotto, A. A.; Mackay, D. H.; See, Wyke Chun Victor; Donati, J. -F.; Folsom, C. P.; Jeffers, S. V.; Marsden, Steve; Morin, J.; Petit, P. (2017-03-21) - Journal article
    The magnetic geometry of the surface magnetic fields of more than 55 cool stars have now been mapped using spectropolarimetry. In order to better understand these observations, we compare the magnetic field topology at ...
  • Exploring the magnetic topologies of cool stars 

    Morin, J.; Donati, J.-F.; Petit, P.; Albert, L.; Auriére, M.; Cabanac, R.; Catala, C.; Delfosse, X.; Dintrans, B.; Fares, R.; Forveille, T.; Gastine, T.; Jardine, M.; Konstantinova-Antova, R.; Lanoux, J.; Lignires, F.; Morgenthaler, A.; Paletou, F.; Velez, J. C. Ramirez; Solanki, S. K.; Thado, S.; Van Grootel, V. (Cambridge University Press, 2011-08) - Conference item
    Magnetic fields of cool stars can be directly investigated through the study of the Zeeman effect on photospheric spectral lines using several approaches. With spectroscopic measurement in unpolarised light, the total ...
  • The first Doppler images of the eclipsing binary SZ Piscium 

    Xiang, Yue; Gu, Shenghong; Cameron, Andrew Collier; Barnes, John Robert; Zhang, Liyun (2016-02-11) - Journal article
    We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September-December. The least-squares deconvolution ...
  • The HARPS search for southern extra-solar planets. XXXIX. HD175607 the most metal-poor G dwarf with an orbiting sub-Neptune 

    Mortier, Annelies; Faria, J. P.; Santos, N. C.; Rajpaul, V.; Figueira, P.; Boisse, I.; Cameron, Andrew Collier; Dumusque, X.; Lo Curto, G.; Lovis, C.; Mayor, M.; Melo, C.; Pepe, F.; Queloz, D.; Santerne, A.; Ségransan, D.; Sousa, S. G.; Sozzetti, A.; Udry, S. (2016-01) - Journal article
    Context. The presence of a small-mass planet (Mp < 0.1 MJup) seems, to date, not to depend on metallicity, however, theoretical simulations have shown that stars with subsolar metallicities may be favoured for harbouring ...
  • Ionization in atmospheres of brown dwarfs and extrasolar planets VI : properties of large-scale discharge events 

    Bailey, R.L.; Helling, Christiane; Hodosán, G.; Bilger, C.; Stark, C.R. (2014-03-20) - Journal article
    Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged ...
  • A Kepler study of starspot lifetimes with respect to light-curve amplitude and spectral type 

    Giles, Helen A. C.; Collier Cameron, Andrew; Haywood, Raphaëlle D. (2017-12-01) - Journal article
    Wide-field high-precision photometric surveys such as Kepler have produced reams of data suitable for investigating stellar magnetic activity of cooler stars. Starspot activity produces quasi-sinusoidal light curves whose ...
  • Multiple views of magnetism in cool stars 

    Morin, J.; Jardine, Moira Mary; Reiners, A.; Shulyak, D.; Beeck, B.; Hallinan, G.; Hebb, Leslie; Hussain, Gaitee Ara Jaffer; Jeffers, Sandra Victoria; Kochukhov, O.; Vidotto, Aline; Walkowicz, L. (2013-02-01) - Journal article
    Magnetic fields are regarded as a crucial element for our understanding of stellar physics. They can be studied with a variety of methods which provide complementary – and sometimes contradictory – information about the ...
  • The MUSCLES Treasury Survey. I. Motivation and overview 

    France, Kevin; Parke Loyd, R. O.; Youngblood, Allison; Brown, Alexander; Schneider, P. Christian; Hawley, Suzanne L.; Froning, Cynthia S.; Linsky, Jeffrey L.; Roberge, Aki; Buccino, Andrea P.; Davenport, James R. A.; Fontenla, Juan M.; Kaltenegger, Lisa; Kowalski, Adam F.; Mauas, Pablo J. D.; Miguel, Yamila; Redfield, Seth; Rugheimer, Sarah; Tian, Feng; Vieytes, Mariela C.; Walkowicz, Lucianne M.; Weisenburger, Kolby L. (2016-03-22) - Journal article
    Ground- and space-based planet searches employing radial velocity techniques and transit photometry have detected thousands of planet-hosting stars in the Milky Way. With so many planets discovered, the next step toward ...
  • A path towards understanding the rotation-activity relation of M dwarfs with K2 mission, X-ray and UV data 

    Stelzer, B.; Damasso, M.; Scholz, A.; Matt, S. P. (2016-12-01) - Journal article
    We study the relation between stellar rotation and magnetic activity fora sample of 134 bright, nearby M dwarfs observed in the Kepler Two-Wheel (K2) mission during campaigns C0-C4. The K2 light curves yield photometrically ...
  • Planets and stellar activity : hide and seek in the CoRoT-7 system 

    Haywood, R. D.; Cameron, A. Collier; Queloz, D.; Barros, S. C. C.; Deleuil, M.; Fares, R.; Gillon, M.; Lanza, A. F.; Lovis, C.; Moutou, C.; Pepe, F.; Pollacco, D.; Santerne, A.; Segransan, D.; Unruh, Y. C. (2014-09-21) - Journal article
    Since the discovery of the transiting super-Earth CoRoT-7b, several investigations have yielded different results for the number and masses of planets present in the system, mainly owing to the star's high level of activity. ...
  • A small survey of the magnetic fields of planet-host stars 

    Fares, R.; Moutou, C.; Donati, J.-F.; Catala, C.; Shkolnik, E. L.; Jardine, M. M.; Cameron, A. C.; Deleuil, M. (2013-10-21) - Journal article
    Using spectropolarimetry, we investigate the large-scale magnetic topologies of stars hosting close-in exoplanets. A small survey of 10 stars has been done with the twin instruments Télescope Bernard Lyot /NARVAL and ...