Engineering topics
DePontieu, B.
Publications and source records attributed to DePontieu, B..
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)
To Understand energy release process in the Sun including solar flares, it is essentially important to measure the magnetic field of the atmosphere of the Sun. Magnetic field measurement of the upper layers (upper chromosphere and above) was technically difficult and not well investigated yet. Upper chromosphere and transition region magnetic field measurement by Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) sounding rocket to be launched in 2015. The proposal is already selected and developments of the flight components are going.
Coronal Loop Evolution Observed with AIA and Hi-C
Despite much progress toward understanding the dynamics of the solar corona, the physical properties of coronal loops are not yet fully understood. Recent investigations and observations from different instruments have yielded contradictory results about the true physical properties of coronal loops. In the past, the evolution of loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this poster we discuss the first results of loop analysis comparing AIA and Hi-C data. We find signatures of cooling in a pixel selected along a loop structure in the AIA multi-filter observations. However, unlike previous studies, we find that the cooling time is much longer than the draining time. This is inconsistent with previous cooling models.
Transverse Prominence Motions from 10,000-250,000 K
We address the origin of prominence material by comparing high cadence (30-60 s) He I and O V EUV observations from SOHO/CDS wide slit movies, and also, for another prominence observation, observations from TRACE at 1216 Angstroms and 1600 Angstroms\and SVST in H\alpha. The EUV and UV observations regularly show small scale structures with plane-of-the-sky velocities of 20-80 kilometers per second. Many, although not all, of these motions are seen in multiple wavelength bands, representing temperatures ranging from 10,000 -- 100,000 K or 20,000 -- 250,000 K, depending on the data set. The H\alpha observations contain line shift information showing clearly that the associated UV prominence intensity motions do actually represent real mass motions, as opposed to temperature or density waves. The results indicate that the "prominence-corona transition region" is not an outside layer to the prominence as a whole, but is rather associated with smaller scale structures all through the prominence.
Prominence Motions Observed at High Cadences in Temperatures from 10,000 to 250,000 K
We report here for the first time observations of prominence velocities over a wide range of temperatures and with a high time cadence. Our study of ultraviolet movies of prominences reveals that multithermal features with speeds of 5-70 km/s perpendicular to the line of sight are common in the prominences which showed traceable motions. These speeds are noticeably higher than the typical speeds of 5-20 km/s observed in \Ha\ data from "quiet" prominences and are more typical of "activated" prominences in which speeds of up to 40 km/s have been reported. The observations were performed using five separate datasets taken by the Solar and Heliospheric Observatory's Coronal Diagnostic Spectrometer (SOHO/CDS) in its wide slit overlap program mode in lines from He approx.I, O approx. V, and Mg approx. IX and a separate prominence observation taken with both the Transition Region and Coronal Explorer (TRACE) in its 1216 and 1600 \A\ bands and in \Ha\ by the Swedish Vacuum Solar Telescope (SVST) at La Palma. The movies were taken with cadences $> 1$ image per minute and were made simultaneously or near-simultaneously in spectral lines formed at two or more temperatures.