... Mindful of these biases, I can now explore the relations between the measured rotation periods and various other observables. The hypothesis behind monitoring stellar variability is that active stars have asymmetric spot distributions on their photospheres. ... They found that only stars with rotation periods greater than seven days show variations greater than 0.4 magnitudes at I. Bouvier et al . ... 1993a) demonstrated a relation between X--ray flux and spectral type in ZAMS stars. ...

We compare atomic gas, molecular gas, and the recent star formation rate (SFR) inferred from HЮБ in the Small Magellanic Cloud (SMC). ... This allows us to disentangle conversion factor effects from the impact of metallicity on the formation and star formation efficiency of molecular gas. ... At a fixed total gas surface density the SMC has a 5-10 times lower molecular gas fraction (and star formation rate) than large spiral galaxies. ...

... Key words: stars: magnetic fields ­ stars: chemically p eculiar 1 Intro duction On the basis of all the available published magnetic measurements for Ap stars we have found a few relations describing the frequency of o ccurrence of the sp ecific magnetic field intensity for all typ es of chemical p eculiarities (Bychkov et al. 2003a). ... Magnetization of stars in the `strongly'-magnetic group exceeds that in the `weak'-magnetic group typically by a factor of 5­10, on the average. ...

A comparative study of type I and type II supernovae . ... Sternberg State Astronomical Institute, Moscow, U.S.S.R. (Received 26 November, 1985) . ... No significant difference between SNe I and SNe II has been found in their radial distribution and frequency of outbursts in spiral galaxies. ... The radial distribution of type Ia SNe in spiral galaxies is only slightly steeper than the one for SNe II, while SNe Ib/c are more concentrated towards the central regions. ...

International Service of Geomagnetic Indices (ISGI) of the IAGA . ... World Data Center C1 for Geomagnetism (WDC-C1), . Solar-Terrestrial Physics Division in Copenhagen, Denmark . ... Sodankyl Geophysical Observatory Geomagnetic and Ionospheric Data . Space Physics Text Book (Oulu): Magnetic activity indices . ... Solar Data Analysis Center (SDAC) . ... Mauna Loa Solar Observatory Analysis Center of HAO/NCAR in Boulder, Colorado . ... Neutron Monitor Server , University of Chicago . ...

... A universal physical relation for quasars . ... Harvey Tananbaum and his collaborators have first observed a relation between the soft X-ray and the optical/ultraviolet emission in AGN in 1979. Such relation is nonlinear, and it is usually parameterized as dependence between the logarithm of the monochromatic luminosities at 2500 †Е ( L 2500†Е ) and 2 keV ( L 2keV ) . ... Yet, the dispersion along the L 2500†Е тАУ L 2keV relationship is found to be rather high, typically ~0.35тАУ0.4 in log units. ...

... Up: INSTALLING, AND RUNNING SCHED Previous: Distribution of Schedule Files Contents . This section briefly describes other programs that may be of use when using SCHED. ... That leaves only the geodetic scheduling program SKED which is still the primary tool for scheduling geodetic project. ... Originally the scheduling program for Mark III, SKED is now the standard program for scheduling geodetic VLBI observations. It produces SKED or drg files that are converted to snap files by DRUDG. ...

Next: Estimating the angle Up: Wavelength Calibration Previous: General Description . The wavelength calibration involves a physical equation, the echelle relation and regression analysis to achieve estimates of the dispersion relation. Provided that the echelle dispersion is performed with a grating, any echelle spectrum can be calibrated usually with four lines used as pre-identifications and a catalog of laboratory wavelengths associated to the calibration lamp. ... Echelle Relation) . ...

... The concepts of Fourier frequency and wavelet duration are obviously related. ... Among many sensible definitions, we chose to require that the peak of the wavelet mean spectrum should be matched with the singularity of the Fourier transform of the cosine wave. Then, it can be shown that the frequency of the cosine is related to the wavelet duration by the relation . ... The ambiguous definition of the duration of an event is common to the sizing of any object of irregular shape. ...