Search Publications
Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes
Maraschi, L.; Covino, S.; Antonelli, L. A. +154 more
Context. Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field.
Aims: We study for the first time the possible very high energy γ-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+61 and 1E 2259+586.
Methods: We…
Temperature dependence of ultraviolet line parameters in network and internetwork regions of the quiet Sun and coronal holes
Peter, H.; Curdt, W.; Wang, X. +3 more
Aims: We study the temperature dependence of the average Doppler shift and the non-thermal line width in network and internetwork regions for both the quiet Sun (QS) and the coronal hole (CH), by using observations of the Solar Ultraviolet Measurements of Emitted Radiation instrument onboard the Solar and Heliospheric Observatory spacecraft. …
Helioseismology of sunspots: defocusing, folding, and healing of wavefronts
Gizon, L.; Schunker, H.; Liang, Z. -C. +1 more
We observe and characterize the scattering of acoustic wave packets by a sunspot in a regime where the wavelength is comparable to the size of the sunspot. Spatial maps of wave travel times and amplitudes are measured from the cross-covariance function of the random wave field observed by SOHO/MDI around the sunspot in active region NOAO 9787. We …
Spectral diagnostic of a microflare. Evidences of resonant scattering in C IV 1548 Å, 1550 Å lines
Gontikakis, C.; Patsourakos, S.; Winebarger, A. R.
Aims: We study a microflare, classified as a GOES-A1 after background subtraction, which was observed in active region NOAA 8541 on May 15, 1999.
Methods: We used TRACE filtergrams to study the morphology and time evolution. SUMER spectral lines were used to diagnose the chromospheric plasma (Si ii 1533 Å), transition region plasma (C iv…
Spectral and temporal properties of the supergiant fast X-ray transient IGR J18483-0311 observed by INTEGRAL
Santangelo, A.; Esposito, P.; Ducci, L. +4 more
Context. IGR J18483-0311 is a supergiant fast X-ray transient whose compact object is located in a wide (18.5 d) and eccentric (e ~ 0.4) orbit, which shows sporadic outbursts that reach X-ray luminosities of ~1036 erg s-1.
Aims: We investigated the timing properties of IGR J18483-0311 and studied the spectra during brigh…
Case study of a complex active-region filament eruption
Yan, X. L.; Xue, Z. K.; Kong, D. F. +2 more
Context. We investigated a solar active-region filament eruption associated with a C6.6 class flare and a coronal mass ejection (CME) in NOAA active region 08858 on 2000 February 9.
Aims: We aim to better understand the relationship between filament eruptions and the associated flares and CMEs.
Methods: Using BBSO, SOHO/EIT, and TRACE ob…
Deep multiband surface photometry on a sample of 24 blue compact galaxies. II. A volume-limited sample of 21 emission line galaxies
Östlin, G.; Zackrisson, E.; Bergvall, N. +6 more
Aims: We present deep surface photometry of a volume-limited sample of 21 UM emission line galaxies in broadband optical UBVRI and near infrared (NIR) HKs filters. The sample comprises 19 blue compact galaxies (BCGs) and two spirals.
Methods: We separated the burst and host populations for each galaxy and compared them to stellar evoluti…
Stellar population properties for a sample of hard X-ray AGNs
Minniti, D.; Masetti, N.; Parisi, P. +5 more
Aims: The aim of this paper is to study the stellar population of galaxies hosting an active galactic nucleus (AGN). We studied a subsample of hard X-ray emitting AGNs from the INTEGRAL and Swift catalogs, which were previously identified and characterized through optical spectroscopy. Our analysis provides complementary information, namely a…
Warm gas in protostellar outflows. I. Flows from the low-mass protostars in L1448 and HH211
Menten, K. M.; Güsten, R.; Leurini, S. +3 more
Context. Observations of CO rotational transitions in the 0.3-0.4 millimeter range, now possible from exceptional sites on the ground, provide the opportunity of studying the warm component of molecular outflows in star-forming regions.
Aims: This study aims to characterize the role of the warm gas in high-velocity and collimated outflows fro…
Five fake ultra-luminous X-ray sources
Gutiérrez, C. M.
Context. The nature of ultra-luminous X-ray (ULX) sources is still a matter of debate. Studies of their counterparts in other spectral ranges will help to clarify the nature of those sources.
Aims: Our goal was to identify and characterize the optical counterparts of five sources catalogued as ULXs.
Methods: We obtained optical imaging a…