The evolutionary ayntheaio rnethod is applied to calculate Mgl+MgH λ 5150 and TiO λ 7150 absorption features of integrated spectra and integrated UBV colours of a stellar system. These calculations are used to investigate star formation rate in nuclei of some spiral galaxies. The (IMg, B-V) diagram is shown to be a goo discriminator between metallicity and star formation effects. Star formation rates, metallicities and initial mass function slopes are obtained for the nuclei of 8 spiral galaxies. Star formation rates in nuclei correlate with rotation velocities of galaxies. Dynamical friction of gas clouds system in a galactic stellar disk is the possible cause of that correlation.
This paper deals with the determination of global star formation rates (SPRs) from radlo free-free and submm/FIR dust emission. Masslve, hot and luminous stars interact with the surrounding
interstellar matter (ISM) lonlzing the gas and heating the dust. O star formation rates (OSFR) in the galactic disk are estimated with observed Lyman continuum photon production rates. Extrapolation to lower mass stars with a constant inltial mass function (IMF) yields, however, too high total SFRs. Furthermore, the lock-up rate, i.e. the rate at whlch gas transformed into stars is permanently locked up in low mass and dead stars, can not reproduce the present-day mass distribution of the galactic disk. Agreement between Lyc photon production rate and time integrated lockup rate can be reached by introducing bimodal star formation in the galactic disk. Thls means that induced star formation in main spiral arms produces only masslve stars ≥3mq. while spontaneous star formation in the interarm region produces stars in the total mass range ≥0.1 mq.
Estimates of SFR based on Lyc photon production rates can not easily be applied to external galaxies because of the difficulty to separate radio synchroton and free-free emission. It is found that slmilar problems are encountered in separating the emission from warm dust (heated by OB stars) and cold dust (heated by the general Interstellar radiation field). The relation between IR luminoslťy and star formation actlvity of galaxies is much more complex than previously assumed.
I briefly summarise and give a critique of the work discussed here on the following major topics that were presented at the rate of one per day: bipolar flows and their associated masers and Herbig-Haro objects; the initial mass function; the large scale gas and kinematical distribution; star clusters; and star formation and starbursts. The dynamics reviews given after my summary promised to be most interesting but are not included here owing to the constraints of causality.
Die angeführten Tafeln sollen mittels des siderischen Jahres den Übergang verschiedener Epochen für das Jahr 1950,0 und umgekehrt erleichtern. Sie sind vor allem für die Falldaten-Vergleichung der Meteorströme bestimmt. Die Epochen der maximalen Tätigkeit der Hauptströme für 1950,0 enthält die Tafel II. and Na straně 13 jsou uvedena shrnutí (Zusammenfassung) k oběma článkům čísla v němčině
The model has 4 components: the extragalactic background, the radiation from the galactic disc and 2 components related to a spur. It fits observations while the hypothetical radio halo does not.
The dust production rates of all the known periodic comets, calibrated by the measurements from the 1986 apparition of comet Halley, are ušed to compute their dust input into the region inside the earth orbit, and the resulting dust fluxes at R = 1 AU. The spatial distribution of tho fresh ejecta and the teraporal variations of their accumulation are reconstructed. Tho visible release of dust is evidently insufficient to maintain the zodiacal cloud in equilibrium.
It is suggested that the progressive decay of the dark matter, including extinct cometary nuclei, their fragments, and products of asteroidal collisions, represents the dominant source of
replenishmont of the interplanetary dust complex.