Publications (13)
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…
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…
Stellar differential rotation from direct starspot tracking
A. Collier Cameron, J. -F. Donati, M. Semel
On the Sun, the rotation periods of individual sunspots not only trace the latitude dependence of the surface rotation rate, but also provide clues as to the amount of subsurface f…
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…
First polarimetric observations and modeling of the FeH F^4 Delta-X^4 Delta system
N. Afram, S. V. Berdyugina, D. M. Fluri +3
Lines of diatomic molecules are more temperature and pressure sensitive than atomic lines, which makes them ideal tools for studying cool stellar atmospheres an internal structure…
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…