Search Publications
UVCS/SOHO investigation of the interface between streamers and coronal holes
Romoli, M.; Spadaro, D.; Ventura, R. +1 more
We investigated the properties of the interface between streamers and coronal holes at low heliocentric distances, observing the extended solar corona in the North-West quadrant by UVCS/SOHO. We measured the line profiles of the H I Lyα and O VI resonance doublet and the visible linearly polarized radiance at heliocentric distances ranging from 1.…
Explosive events in the solar atmosphere seen in extreme-ultraviolet emission lines
Wilhelm, K.; Mendoza-Torres, J. E.; Torres-Papaqui, J. P.
We present observations of explosive events (EEs) in the solar atmosphere obtained with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO) in the wavelength range from about 750 Å to 790 Å. Prominent spectral lines in this range are emitted by ions which have temperatures o…
Diffuse galactic sub-MeV γ -ray excess from high-energy electrons
Strong, A. W.; Schlickeiser, R.; Schröder, R.
Recent INTEGRAL observations have confirmed the existence of diffuse sub-MeV radiation from the inner Galaxy. We propose a new explanation for the origin of this diffuse component in terms of electrostatic bremsstrahlung radiation from high-energy electrons. This electrostatic bremsstrahlung interpretation requires a very flat power law energy spe…
Large-scale photospheric dynamics below coronal holes
Meunier, N.
A large data set of MDI magnetograms is studied to analyze the global dynamics of magnetic structures from network to active regions inside and outside coronal holes. We find a weaker meridional circulation at almost all latitudes, as well as a more differential rotation of the photospheric magnetic structures below high-latitude coronal holes. St…
VINCI-VLTI measurements of HR 4049: The physical size of the circumbinary envelope
Paresce, F.; Wittkowski, M.; Antoniucci, S.
We present the first detection of the envelope which surrounds the post-AGB binary source HR 4049. VINCI-VLTI K-band interferometric observations of this source imply the existence of a large structure with a Gaussian angular FWHM 22.4 ± 1.4 mas or uniform disk diameter of 34.9 ± 1.9 mas. With the Hipparcos parallax of 1.50 ± 0.64 mas these values…
A cold globule with a Class 0/I embedded source
Lemke, D.; Lehtinen, K.; Mattila, K.
Infrared observations of the dark cloud DC 303.8-14.2 and the embedded point source IRAS 13036-7644 have been made with the ISOPHOT instrument aboard ISO at 7.7 µm, 60 µm, 100 µm and 200 µm. We have compared the properties of dust in DC 303.8-14.2 and the Thumbprint Nebula (TPN), a morphologically similar globule but withou…
Comparison of blinkers and explosive events: A case study
Innes, D. E.; Parnell, C. E.; Brown, D. S. +1 more
Blinkers are brightenings at network cell junctions that are traditionally identified with SOHO/CDS and explosive events or high velocity events are identified in high resolution UV spectra obtained from HRTS and SOHO/SUMER. Criteria are determined to facilitate objective automatic identification of both blinkers and explosive events in both SOHO/…
Probing the nuclear obscuration in radio-galaxies with near infrared imaging
Capetti, A.; Marchesini, D.; Celotti, A.
We present the first near-infrared (K'-band) homogeneous observations of a complete sub-sample of the 3CR radio catalogue comprising all High Excitation Galaxies (HEGs) at z <0.3. After showing that the surface brightness decomposition technique to measure central point-like sources is affected by significant uncertainties for the objects in th…
A search for warm-hot intergalactic medium features in the X-ray spectra of Mkn 421 with the XMM-Newton RGS
Tagliaferri, G.; Ghisellini, G.; Tavecchio, F. +2 more
We present the high-resolution X-ray spectra of Mkn 421 obtained in November 2003 with the RGS aboard the XMM-Newton satellite. This Target of Opportunity observation was triggered because the source was in a high state of activity in the X-ray band. These data are compared with three archival RGS observations of the same source performed in Novem…
Kinematics of Vega-like stars: Lifetimes and temporal evolution of circumstellar dust disks
Manoj, P.; Bhatt, H. C.
We have used the velocity dispersion as an age indicator to constrain the ages of a large sample of main sequence Vega-like stars in order to study the lifetimes and temporal evolution of the dust disks around them. We use Hipparcos measurements to compute stellar velocities in the sky plane. The velocity dispersion of Vega-like stars is found to …