Now showing items 1-20 of 36

    • 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 ...
    • Connecting the large- and the small-scale magnetic fields of solar-like stars 

      Lehmann, L. T.; Jardine, M. M.; Mackay, D. H.; Vidotto, A. A. (2018-08-21) - Journal article
      A key question in understanding the observed magnetic field topologies of cool stars is the link between the small- and the large-scalemagnetic field and the influence of the stellar parameters on the magnetic field topology. ...
    • 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. (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 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 ...
    • High-resolution spectroscopy of Boyajian's star during optical dimming events 

      Martínez González, M. J.; González-Fernández, C.; Asensio Ramos, A.; Socas-Navarro, H.; Plaza, C. Westendorp; Boyajian, T. S.; Wright, J. T.; Cameron, A. Collier; González Hernández, J. I.; Holgado, G.; Kennedy, G. M.; Masseron, T.; Molinari, E.; Saario, J.; Simón-Díaz, S.; Toledo-Padrón, B. (2019-06) - Journal article
      Boyajian’s star is an apparently normal main-sequence F-type star with a very unusual light curve. The dipping activity of the star, discovered during the Kepler mission, presents deep, asymmetric, and aperiodic events. ...
    • 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 ...
    • Observing the simulations : applying ZDI to 3D non-potential magnetic field simulations 

      Lehmann, L. T.; Hussain, G. A. J.; Jardine, M. M.; Mackay, D. H.; Vidotto, A. A. (2019-03-11) - Journal article
      The large-scale magnetic fields of stars can be obtained with the Zeeman-Doppler-Imaging (ZDI) technique, but their interpretation is still challenging as the contribution of the small-scale field or the reliability of the ...