We demonstrate that the atomic alignment of the hyperfine-structure components of the ground-level S1/2 of Na I and of the upper-level P1/2 of the D1 line are practically negligible for magnetic strengths B>10 G and virtually zero for B>~100 G. This occurs independently of the magnetic field inclination on the stellar surface (also, in particular

During the post-AGB phase the dust shell detaches from the central star and dust temperatures varies between 100 and 200 K. In order to study the onset of photo-ionization in post-AGB stars, IRSPEC near-infrared spectroscopy of 40 IRAS sources from the Point Source Catalogue was conducted. In 27 of the post-AGB observed Br gamma is detected. In

We discuss here the nature of a rich zoo of knots, filaments, jets and jet-like systems, located--in terms of morphology and kinematics--either inside or outside the main nebular bodies of planetary nebulae (PNe). These features are low-ionization structures (LISs) especially prominent in [N II] and other low-ionization line emission, which are

EMIR is a multiobject intermediate resolution near infrared (1.0 - 2.5 microns) spectrograph with image capabilities to be mounted on the Gran Telescopio Canarias (Observatorio del Roque de los Muchachos, La Palma, Spain). EMIR is under design by a consortium of Spanish, French and British institutions, led by the Instituto de Astrofisica de

We study the effect that the temperature structure has on the determination of the primordial helium abundance, Yp. We provide an equation linking T(O III), the temperature derived from the [O III] lines, and T(He II), the temperature of the He I lines, both for H II regions with O++ only and for H II regions where a fraction of O+ is present. By

IAUC 7821 available at Central Bureau for Astronomical Telegrams.