465 citations · 922 across the 14 of their papers we have counts for
15 papers
On the degeneracy of solutions from stellar spectropolarimetric data
J. C. Ramirez Velez, J. M. Raygoza-Romero, I. H. Lopez-Nava +3
In this work we investigate the inversion accuracy of stellar magnetic fields through the analysis of spectropolarimetric data. We performed several noise free tests to untangle th…
Multi-band polarimetry of post-asymptotic giant branch stars stars. Optical measurements
S. Akras, J. C. Ramirez Velez, N. Nanouris +4
We present new optical broad-band (UBVRI) aperture polarimetric observations of 53 post-asymptotic giant branch (AGB) stars selected to exhibit a large near-infrared excess. 24 out…
Stellar longitudinal magnetic field determination through multi-Zeeman signatures
J. C. Ramírez Vélez, M. J. Stift, S. G. Navarro +3
Context. A lot of effort has been put into the detection and determination of stellar magnetic fields using the spectral signal obtained from the combination of hundreds or thousan…
Long-term magnetic field monitoring of the Sun-like star ξBootis A
A. Morgenthaler, P. Petit, S. Saar +13
Aims. We aim to investigate the long-term temporal evolution of the magnetic field of the solar-type star ξBootis A, both from direct magnetic field measurements and from the simul…
Magnetic fields and differential rotation on the pre-main sequence III: The early-G star HD 106506
I. A. Waite, S. C. Marsden, B. D. Carter +5
We present photometry and spectropolarimetry of the pre-main sequence star HD 106506. A photometric rotational period of ~1.416 +/- 0.133 days has been derived using observations a…
Magnetic fields and differential rotation on the pre-main sequence II: The early-G star HD 141943 - coronal magnetic field, H-alpha emission and differential rotation
S. C. Marsden, M. M. Jardine, J. C. Ramírez Vélez +8
Spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at three observing epochs (2007, 2009 and 2010). The observations were obtained using…
Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies
S. C. Marsden, M. M. Jardine, J. C. Ramírez Vélez +8
Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observ…
Long-term magnetic field monitoring of the Sun-like star Ksi Bootis A
A. Morgenthaler, P. Petit, M. Auriere +11
Phase-resolved observations of the solar-type star Ksi Bootis A were obtained using the NARVAL spectropolarimeter at the Telescope Bernard Lyot (Pic du Midi, France) during years 2…
Exploring the magnetic topologies of cool stars
J. Morin, J. -F. Donati, P. Petit +19
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 measur…
Spectropolarimetric multi line analysis of stellar magnetic fields
J. C. Ramirez Velez, M. Semel, M. Stift +3
In this paper we study the feasibility of inferring the magnetic field from polarized multi-line spectra using two methods: The pseudo line approach and The PCA-ZDI approach. We us…
Multiline Zeeman Signatures Through Line Addition
M. Semel, J. C. Ramirez Velez, M. J. Martinez Gonzalez +4
In order to get a significant Zeeman signature in the polarised spectra of a magnetic star, we usually 'add' the contributions of numerous spectral lines; the ultimate goal is to r…
Surface magnetic fields on two accreting T Tauri stars: CV Cha and CR Cha
G. A. J. Hussain, A. Collier Cameron, M. M. Jardine +12
We have produced brightness and magnetic field maps of the surfaces of CV Cha and CR Cha: two actively accreting G and K-type T Tauri stars in the Chamaeleon I star-forming cloud w…
Large-scale magnetic topologies of mid-M dwarfs
J. Morin, J. -F. Donati, P. Petit +13
We present in this paper the first results of a spectropolarimetric analysis of a small sample (~ 20) of active stars ranging from spectral type M0 to M8, which are either fully-co…
Strength distribution of solar magnetic fields in photospheric quiet Sun regions
J. C. Ramirez Velez, A. Lopez Ariste, M. Semel
The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field stre…
PCA detection and denoising of Zeeman signatures in stellar polarised spectra
M. J. Martinez Gonzalez, A. Asensio Ramos, T. A. Carroll +3
Our main objective is to develop a denoising strategy to increase the signal to noise ratio of individual spectral lines of stellar spectropolarimetric observations. We use a multi…