Abstract. This paper presents and discusses the final data set of a long-term and short-spaced monitoring of 21 SiO maser sources, mostly evolved stars, carried out in two SiO maser lines at 43 GHz with the Observatorio Astronómico Nacional 13.7 m telescope at the Centro Astronómico de Yebes (Guadalajara, Spain). In most objects, more than 80 spectra per transition over a period of 11 years have been recorded. The new data presented here, previously unpublished, represent nearly 50% of the total SiO data collected in the project. In addition, the availability of optical light curves from the AAVSO for most of the objects during the whole period of the SiO monitoring, ground-based near-IR data for four sources overlapping with 3 to 5 observed SiO periods, and DIRBE near-IR data covering a significant portion of an SiO period in 10 sources, make this data set a unique reference for comparing optical, NIR and SiO variability in order to elucidate the physical mechanisms that pump SiO masers in evolved stars. The basis for the conclusions obtained in this work comes from a numerical time series analysis of the suitable SiO, optical and NIR light curves in regular variables to obtain precise values of the periods and phase lags between the different curves. This analysis shows evidence that in regular variable evolved stars the three types of emission have the same period and that the SiO maxima happen in phase with NIR maxima and with a phase lag typically between 0.05 and 0.20 with respect to optical maxima. We conclude that in these objects the observational evidence presented in this work favors the radiative pumping of SiO masers against the collisional pumping.

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Abstract. We present the results from a monitoring of the v = 1 and v = 2, J = 1−0 28 SiO maser emission in 21 objects, covering all types of known SiO maser emitters: 13 Mira variables, 2 long period semiregulars (SRGs), 3 variable supergiants (SGs), 2 OH/IR stars, and one young stellar object. This study has been carried out with the 13.7 meter radiotelescope of the Centro Astronómico de Yebes (Guadalajara, Spain), from July 1984 to May 1990, and represents the longest and most tightly sampled monitoring of SiO masers ever published.Our data show that for Mira-type (i.e. regular) variables, the SiO and optical light curves agree in period, and that the maxima of the SiO emission lag the optical ones by about 0.1 − 0.2 periods. Since a similar lag characterizes the near infrared (NIR) emission variability from these stars, we conclude that for regular variables SiO and NIR vary in phase. This result was confirmed in three objects for which NIR variability curves are available. For SRGs and SGs, we found a less systematic behavior, but when the SiO emission is periodic, its variability curve agrees with the optical one, also showing a lag between maximum epochs similar to that of Mira-type stars. The data clearly reveal other interesting details on the SiO maser variability, such as the strong intensity differences between different maxima and changes in the velocity distribution of the emission. Finally, the SiO masers associated to the young stellar object Orion IRc2 showed a double peaked spectrum with low amplitude, aperiodic variations.

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A sample of 2.2 million hadronic Z decays, selected from the data recorded by the DELPHI detector at LEP during 1994-1995 was used for an improved measurement of inclusive distributions of pi (+), K+ and p and their antiparticles in gluon and quark jets. The production spectra of the individual identified particles were found to be softer in gluon jets compared to quark jets, with a higher multiplicity in gluon jets as observed for inclusive charged particles. A significant proton enhancement in gluon jets is observed indicating that baryon production proceeds directly from colour objects. The maxima, xi*, of the S-distributions for kaons in gluon and quark jets are observed to be different