arXiv subjects

V. Martinez Pillet

Publications and source records attributed to V. Martinez Pillet.

39 records · Page 3Linked to original sources

arXiv2006

Evidence of an association between the presence of penumbrae and strong radial outflows in sunspots

Time series of high-resolution images of the complex active region NOAA 10786 are studied. The observations were performed in G-band (430.5 nm) and in the nearby continuum (463.3 nm), on July 9, 2005 at the Swedish 1-meter Solar Telecope (SST) in La Palma. Granular proper motions in the surroundings of the sunspots have been quantified. A large-scale radial outflow in the velocity range 0.3 - 1 km s^[-1] has been measured around the sunspots by using local correlation tracking techniques. However, this outflow is not found in those regions around the sunspots with no penumbral structure. This result evidences an association between penumbrae and the existence of strong horizontal outflows (the moat) in sunspots.

astro-ph↗

arXiv2006

Simulation and analysis of VIM measurements: feedback on design parameters

The Visible-light Imager and Magnetograph (VIM) proposed for the ESA Solar Orbiter mission will observe a photospheric spectral line at high spatial resolution. Here we simulate and interpret VIM measurements. Realistic MHD models are used to synthesize "observed" Stokes profiles of the photospheric Fe I 617.3 nm line. The profiles are degraded by telescope diffraction and detector pixel size to a spatial resolution of 162 km on the solar surface. We study the influence of spectral resolving power, noise, and limited wavelength sampling on the vector magnetic fields and line-of-sight velocities derived from Milne-Eddington inversions of the simulated measurements. VIM will provide reasonably accurate values of the atmospheric parameters even with filter widths of 120 mA and 3 wavelength positions plus continuum, as long as the noise level is kept below 10^-3 I_c.

astro-ph↗

arXiv2005

Spectro-polarimetric observations and non-LTE Modeling of Ellerman bombs

Ellerman bombs are bright emission features observed in the wings of H$α$, usually in the vicinity of magnetic concentrations. Here we show that they can also be detected in the Ca II infrared triplet lines, which are easier to interpret and therefore allow for more detailed diagnostics. We present full Stokes observations of the 849.8 and 854.2 nm lines acquired with the new spectro-polarimeter SPINOR. The data shows no significant linear polarization at the level of 3x10$^{-4}$. The circular polarization profiles exhibit measureable signals with a very intricate pattern of peaks. A non-LTE analysis of the spectral profiles emerging from these features reveal the presence of strong downflows (~10 km/s) in a hot layer between the upper photosphere and the lower chromosphere.

astro-ph↗