Search Publications
Extended Red Emission and the evolution of carbonaceous nanograins in NGC 7023
Cuillandre, J. -C.; Joblin, C.; Thomas, J. +3 more
Context: Extended Red Emission (ERE) was recently attributed to the photo-luminescence of either doubly ionized Polycyclic Aromatic Hydrocarbons (PAH++), or charged PAH dimers ([PAH{2}] ^+).
Aims: We analysed the visible and mid-infrared (mid-IR) dust emission in the North-West and South photo-dissociation regions of the reflection …
A 1.3 cm wavelength radio flare from a deeply embedded source in the Orion BN/KL region
Menten, K. M.; Reid, M. J.; Forbrich, J.
Aims:Our aim was to measure and characterize the short-wavelength radio emission from young stellar objects (YSOs) in the Orion Nebula Cluster and the BN/KL star-forming region.
Methods: We used the NRAO Very Large Array at a wavelength of λ=1.3 cm and we studied archival X-ray, infrared, and radio data.
Results: During our observation, a …
The X-ray luminosity of solar-mass stars in the intermediate age open cluster NGC 752
Micela, G.; Favata, F.; Giardino, G. +1 more
Aims: While observational evidence shows that most of the decline in a star's X-ray activity occurs between the age of the Hyades (~ 8 × 108 yr) and that of the Sun, very little is known about the evolution of stellar activity between these ages. To gain information on the typical level of coronal activity at a star's intermediate age, …
A deep INTEGRAL hard X-ray survey of the 3C 273/Coma region
Paltani, S.; Walter, R.; Dwelly, T. +3 more
We present an analysis of the deepest hard X-ray survey to date of about 2500 deg2 performed by the IBIS instrument on board INTEGRAL in the 20-60 keV band, with a total exposure time of 4 Ms. We find 34 candidate sources, for which we try to find counterparts at other wavelengths. The ratio of Seyfert 1 to Seyfert 2 is significantly mo…
Intensity oscillations observed with Hinode near the south pole of the Sun: leakage of low frequency magneto-acoustic waves into the solar corona
Srivastava, A. K.; Dwivedi, B. N.; Zaqarashvili, T. V. +1 more
Aims: We study intensity oscillations in the solar chromosphere and corona, above a quiet-Sun magnetic network.
Methods: We analyse the time series of He II 256.32 Å, Fe XI 188.23 Å and Fe XII 195.12 Å spectral lines, observed close to the south pole, by the EUV Imaging Spectrometer (EIS), onboard Hinode. We use a standard wavelet tool, to pro…
Long-period oscillations in solar coronal bright points
Li, S.; Tian, H.; Xia, L. -D.
Aims: By analyzing TRACE (Transition Region and Coronal Explorer) data, we investigate intensity oscillations in coronal bright points (BPs) as well as the underlying chromosphere.
Methods: A Fourier analysis is applied to a sequence of images observed in the 195 Å and 1216 Å passbands of TRACE. We produce images of Fourier power in three diff…
INTEGRAL observations of the variability of OAO 1657-415
Klochkov, D.; Santangelo, A.; Wilms, J. +7 more
Context: The Galactic Plane Scan (GPS) was one of the core observation programmes of the INTEGRAL satellite. The highly variable accreting pulsar
Aims: We investigate the spectral and timing properties of OAO 1657-415 and their variability on short and long time scales in …
X-ray spectral variability in PG 1535+547: the changing look of a ``soft X-ray weak'' AGN
Cappi, M.; Vignali, C.; Schartel, N. +5 more
Context:
Origin of chromatic features in multiple quasars. Variability, dust, or microlensing
Yonehara, A.; Richter, P.; Hirashita, H.
Aims:In some of lensed quasars, color differences between multiple images are observed at optical/near-infrared wavelengths. There are three possible origins for the color differences: intrinsic variabilities of quasars, differential dust extinction, and quasar microlensing. We examine how these possible scenarios can reproduce the observed chroma…
Sizes of transition-region structures in coronal holes and in the quiet Sun
Tu, C. -Y.; Marsch, E.; Tian, H. +2 more
Aims: We study the height variations of the sizes of chromospheric and transition-region features in a small coronal hole and the adjacent quiet Sun, considering images of the intensity, Doppler shift, and non-thermal motion of ultraviolet emission lines as measured by SUMER (Solar Ultraviolet Measurements by Emitted Radiation), together with the …