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Excess facular emission from an isolated active region during solar minimum: the example of NOAA AR 7978
Sanahuja, B.; Fröhlich, C.; Ortiz, A. +1 more
The facular contribution to solar irradiance variations on the short time scale is studied by analyzing a simple case of an isolated active region that crossed the solar disk during the 1996 minimum of activity, NOAA AR 7978. Its passage during several Carrington rotations, specifically from rotation 1911 to 1916, allows us to analyze the evolutio…
Properties and nature of Be stars. XXII. Long-term light and spectral variations of the new bright Be star HD 6226
Buil, C.; Harmanec, P.; Yang, S. +8 more
Photometric and spectroscopic monitoring of the B star HD 6226 resulted in the finding that this object is a new bright Be star with a clear positive correlation between the brightness and emission-line strength. The emission-line episodes are relatively short and seem to repeat frequently which makes this star an ideal target for studying the cau…
Monte Carlo simulations of CASSINI/LEMMS
Livi, S.; Haggerty, D. K.
In an effort to characterize the response of the low energy magnetospheric measurements system (LEMMS) on the CASSINI spacecraft to energetic ions and electrons we have taken advantage of the excellent pre-launch beam calibrations in comparison to an extensive series of electron and ion Monte Carlo simulations. We selected the geometry and trackin…
Faint 6.7 Micron Galaxies and Their Contributions to the Stellar Mass Density in the Universe
Matsuhara, Hideo; Cowie, Lennox L.; Taniguchi, Yoshiaki +6 more
We discuss the nature of faint 6.7 µm galaxies detected with the mid-infrared camera ISOCAM on board the Infrared Space Observatory (ISO). The 23 hr integration on the Hawaii Deep Field SSA13 has provided a sample of 65 sources down to 6 µJy at 6.7 µm. For 57 sources, optical or near-infrared counterparts were found using a stati…
Empirical Absolute Magnitudes, Luminosities and Effective Temperatures of SPB Variables and the Problem of Variability Classification of Monoperiodic Stars
Molenda-Zakowicz, J.; Polubek, G.
We derive semi--empirical log L/Lodot for 27 stars classified as SPB on the basis of Hipparcos photometry and we plot these stars on the log Teff-log L/Lodot diagram. We confirm pulsations of HIP 63210 and HIP 108348 and show that luminosities and masses derived from photometry are of limited use for asteroseismolo…
The XMM-Newton/2dF survey - VII. Is there any X-ray absorption in optically selected QSOs?
Georgakakis, A.; Georgantopoulos, I.; Akylas, A.
We explore the X-ray properties of optically selected quasi-stellar objects (QSOs) spectroscopically identified in the course of the 2dF QSO survey (2QZ). Our main goal is to expand to higher redshifts, previous findings suggesting the presence of a fraction of X-ray obscured sources among the low-redshift, optically selected, broad line active ga…
Principal component analysis of International Ultraviolet Explorer galaxy spectra
Brosch, Noah; Formiggini, Liliana
We analyse the UV spectral energy distribution of a sample of normal galaxies listed in the International Ultraviolet Explorer (IUE) Newly Extracted Spectra (INES) Guide No. 2 - Normal Galaxies using a principal component analysis. The sample consists of the IUE short-wavelength (SW) spectra of the central regions of 118 galaxies, where the IUE ap…
Observational evidence of pitch angle isotropization by IMF waves
Bochsler, P.; Klecker, B.; Möbius, E. +4 more
A statistical analysis of interstellar He+ pickup ion measurements from SOHO/CTOF combined with magnetic field data from WIND/MFI enable quantitative study of wave-particle interactions in the inner heliosphere for the first time. Magnetic field vector measurements with a time resolution of 3 seconds are used to determine power spectrum…
A search for X-ray flashes with XMM-Newton
Law, Nicholas M.; Kulkarni, Shrinivas R.; Rutledge, Robert E.
We searched for X-ray flashes (XRFs) - which we defined as ~10-s duration transient X-ray events observable in the 0.4-15 keV passband - in fields observed using XMM-Newton with the EPIC/pn detector. While we find two non-Poissonian events, the astrophysical nature of the events is not confirmed in fully simultaneous observations with the EPIC/MOS…
Diagnostics of the Local Interstellar Medium using particles and UV radiation
Lallement, R.; Vallerga, J.; Raymond, J. R.
The chain of processes which govern trajectories and ionization of neutral particles from the circumsolar interstellar gas to the inner heliosphere can now be studied by combining several types of diagnostics: solar backscattered radiation (H and He), direct detection of neutral particles (He), detection of pickup ions of interstellar origin (H, H…