Extensive infrared observations were taken of OJ 287 in 1993/94 as part of an on-going monitoring campaign of this object started in 1988. The data show that this blazar reached very high levels in the infrared in Fall'94 after a continuous increase in brightness through the winter and spring of 1993/94. The infrared fluxes registered at maximum

A magnetic flux tube anchored at the bottom of the solar convection zone and rising toward the surface as a result of an undulatory instability can be affected by a sudden catastrophic expansion and weakening of the magnetic field at its apex if the original field strength is below a few times 104 G. Such an "explosion" occurs if the flux tube

We have measured the ^12^C/^13^C interstellar ratio in the Coalsack, a prominent dark nebula in the southern sky, by means of high resolution (λ/δλ=6x10^4^) observations of the λ4232A CH^+^ line in the direction of the star HD110432 (d=~0.31kpc). The collection of a total of 53 spectra of this star and of a reference bright star (α Vir) has allowed

By combining the C III λλ1906+1909 with the C II λ4267 line intensities it is possible to determine T(C++); this temperature is, in general, considerably smaller than T(O++), the temperature derived from the O III λ4363 to λ5007 intensity ratio. The authors study possible causes for this difference. They show that in the presence of spatial

The authors present two new methods to determine the electron temperature based on the He I line intensities. The temperatures derived from these methods are considerably smaller than those derived from the [O III] λλ4363, 5007 line intensities and imply the presence of large spatial temperature fluctuations in PNe. Considering the presence of

Bidimensional spectroscopy with good spatial and spectral resolution, sampling a particular emission line over the whole emitting area, is shown here to be the most suitable observational technique for understanding the kinematics of giant extragalactic H II regions (GEHRs). The TAURUS II Fabry-Perot spectrograph is an excellent instrument for this