We review briefly the observational status of abundance determinations for those elements produced in the first seconds of a “standard” Big Bang Universe, showing that although [4He] and [D] appear not to be mutually compatible there is still room for reconciliation via astration of D, for values consistent with estimated [7Li]. New limits to production cross-sections for 7Li appear to limit N v (the number of light neutrino types) to no more than 3. Non-standard models with fluctuations are briefly considered; they are attractive because they use Ω = 1 and may also yield early C, N, O in significant quantities. The true value of 7Li [10-9 or 10−10 w.r.t. H] is the critical test here. We show where spectra of improved S:N are needed to progress in constraining cosmological models.

Selecting stars with previously measured or estimated rotational periods we measured Li equivalent widths in 8 stars of the Hyades late main sequence. Combining our data with literature values, we derive a homogeneous set of Li abundances. Plotting log N(Li) against Rossby number we can separate the effects of temperature and rotation. We find for stars later than F8 increased depletion with longer period, at constant surface temperature. Discounting, as improbable, spurious abundances due to surface activity effects, we give a tentative view of the implications of these results for stellar modelling.

Monitoring of active late-type dwarfs, spectroscopically with high resolution (λ/Δλ ∼ 105) and high S:N (>300) round their activity cycles, principally in the Call H resonance line, offers techniques to explore (a) plage filling factors (b) 3-dimensional chromospheric velocity fields (c) maps of surface activity via “Doppler Imaging”. In this paper we deal with the use of spectral signatures to derive plage cover.

We discuss the present limits to the velocity field diagnostics in stellar chromospheres achievable with ESO CAT+CES and IUE high resolution spectra.

Spectra of resolution λ/Δλ∼2 ×104 and good S:N ratio are presented in the range containing the 7Li doublet at 6707 Å for 9 main sequence or slightly evolved stars in NGC 752 (age ∼2 ×109 years). We investigate the suggested main sequence bimodality using spectroscopic indications of binarity and high rotational velocity, as well as the Li abundance to supplement previous photometry.

High resolution, high S:N spectra are used to determine the abundances of Fe, Ni, Ca, Al and Si in 25 field dwarfs with −1.2<[Fe/H]< +0.3. We find overabundances for Al, Ca and Si in stars with −1.2<[Fe/H]< −0.5 and solar [Ni/Fe] over the whole studied range.

We have developed a new stellar population synthesis model for calculating colours and absorption line indices in early type galaxies. This model can work either for single-age stellar populations or in an evolutionary scheme following the chemical evolution. The model is based on the isochrones of the Padova group and we have developed our own method of conversion to colours. Details can be found in Vazdekis A., Casuso E., Peletier R. & Beckman J. (submitted, 1995). To test the model we have obtained accurate observations in many colours and line indices of the three standard galaxies: NGC 3379, NGC 4472 and NGC 4594.

There are two principal problems in explaining, in terms of the emission from OB stars, the ionisation of gas which emits diffuse Hα in spiral galaxies. One is the long pathlength which the ionising photons need to traverse to reach their objectives, the other is whether sufficient photons can escape from within the H II regions which surround the hot stars. Here we treat the second point, assuming that the H II regions above a certain threshold luminosity are density bounded. We calculate the escaping Lyman continuum (Lyc) fluxes from the density bounded regions in four galaxies, and show that in each of them this is easily suffcient to produce the measured diffuse Hα emission.

We have used the TAURUS Fabry–Perot mapping spectrometer on the William Herschel telescope (WHT) to produce a complete kinematic map of the disk of M100 in Hα. Here we show how the internal velocity dispersion (σ) of the principal emission components of the brightest regions varies with their Hα luminosity. The plot shows ample scatter, but an upper envelope in σ is clearly linear (in the log–log plane) with a slope of 2·6, a result which agrees precisely with an earlier graph by Arsenault et al., who selected instead the regions of highest surface brightness. We show that this result, which differs from the conventional prediction from the virial theorem, is consistent with virialisation if the H II regions are density bounded, and thus offers evidence in support of the density bounding hypothesis for the most luminous regions in disk galaxies.

We have obtained the oxygen abundance in a sample of 44 F-type dwarfs in the Ursa Major group and the Hyades open cluster, using an NLTE analysis of the O I infrared triplet at λλ 7771-7775 Å. These clusters show the “lithium gap” in the F spectral range, and it has been suggested that if this phenomenon were due to microscopic diffusion, their Li-depleted stars could also show oxygen and/or nitrogen depletion. Our results here show a substantial measure of uniformity in the oxygen abundances. The data might indicate a very small dip (< 0.1 dex) in the O abundance for stars located in the Li gap. Microscopic diffusion seems to be the only known mechanism able to produce an oxygen dip. If this mechanism were responsible for the Li gap, it would have to account for a depletion of up to two orders of magnitude in Li and, at the same time, less than 0.1 dex in oxygen. We note that turbulent mixing could modify a microscopic diffusion pattern in order to yield the observed abundances of the two elements.

High-resolution optical and NIR observations are used to constrain a dynamical model of the circumnuclear star forming (SF) region in the barred galaxy M100 (NGC 4321). Small leading arms observed in our K-band image of the nuclear region have been reproduced in numerical modeling of M100, a galaxy with a double inner Lindblad resonance (ILR). We also present preliminary optical and NIR observations of NGC 6951: a barred galaxy with circumnuclear SF showing a distinctly different behavior to M100 at 2.2µm.

We present new high quality Ha continuum-subtracted images of the grand design galaxies NGC 157, NGC 3631, NGC 6764, and NGC 6951, two of them barred and two non-barred, and describe the statistical properties of the HII regions. We have determined the positions, angular sizes and fluxes of individual HII regions, and construct luminosity functions and diameter and density distributions. We find no significant differences between arm and interarm HII region properties, or between the barred and non-barred galaxies. This paper summarizes work described in more detail by Rozas et al. (1995a,b)

Observations of interstellar Na I in the spectra of 93 stars within 315 pc from the Sun show that it lies in a tunnel of gas moving away from Scorpio-Centaurus and is surrounded by gas moving toward the Galactic center.

Gas approaches the Sun from Scorpio-Centaurus expanding from (r, l, b)=(160 pc, 313°7, +28°2) with LSR velocity 15.3 km s−1. The radius of this shell is 153 pc.

We identify these clouds:

D: velocity vector (υ d, l d, b d)=(+7.2 km s−1, 305°1, −13°5), above and below the Galactic plane (GP) in the range of Galactic longitudes 357°–55°.

C: velocity vector (υ c, l c, b c)=(+11.5 km s−1, 349°0, −35°2), above and below the GP in the range 30°≤l≤110°.

M: velocity vector (υ m, l m, b m)=(+21.9 km s−1, 34°2, +1°5), above and below the GP in the range 100°≤l≤130°.

P: velocity vector (υ p, l p, b p)=(+13.8 km s−1, 244°9, +5°4), above and below the GP from l~120° to the limit of our data at l~210°.

E: velocity vector (υ e, l e, b e)=(+16.8 km s−1, 208°4, +6°2) in the range 160°≤l≤185° and −10°≤b≤–35°.

A: velocity vector (υ a, l a, b a)=(+12.9 km s−1, 73°6, −5°6) towards the Galactic anti-center, below the GP.

I: velocity vector (υ i, l i, b i)=(+37.7 km s−1, 132°8, −64°3) towards the Galactic anti-center, above the GP.

We have monitored Ca II H with a spectral resolution of 8 × 104, in asimple of late-type MS stars over a four-year period. The high resolution enables us to add information on velocity fields to the usual flux monitoring. We detect changes in wavelength of different parts of the Ca II H feature, which can be interpreted as velocity fields in the lower chromosphere, with downflow and upflow of order 0.5 km s−1, depending on the star. Flux variations in Ca II H emission can be ascribed, via velocity tagging, to long-term change in plage cover rather than short-term modulation by (incompletely sampled) rotation cycles.

We have observed seven main sequence stars in the Pleiades, with B – V between 0.98 and 1.41 (5100–3900 K), and with a wide range of rotational velocities, in Ca II H and K, Hα and have derived Li abundances. Our results, combined with literature data, indicate that the most chromospherically active stars are rapid rotators, and that at a given effective temperature the Li-rich stars show the highest chromospheric activity. A different surface coverage of active regions could influence the dichotomy observed in the Li abundance distribution.

We present new beryllium abundances for three unevolved stars with [Fe/H] in the range −0.4 to −1.6. The Be II doublet is detected in the three stars. A spectral synthesis analysis has been conducted to derive the abundances. We briefly discuss their Be and Li abundances, together with a wide sample of stars from the literature, in the context of mixing processes below the convection zone.

We have measured the He I D3 line, λ5876 Å, in 32 F-type young open cluster stars and in 4 field stars. Combining our results with previous observations of D3 we strengthen the following conclusions: (a) Sub-surface convective zones appear, on the main sequence, around F0 (B – V ~ 0.3). (b) The stars between F0 and F5 (0.3 ≲ B – V ≲ 0.42) are chromospherically “active” irrespective of age, which implies a heating mechanism not affected by evolutionary effects. In this range the activity in D3 and X-rays are uncorrelated. (c) For stars later than F5 the correlation among all the activity indices, chromospheric and coronal, shows a common energy source. Convective zones here should be deep enough to generate magnetic fields capable of supplying this energy, and also for braking the rotation.

The Hα brightness distribution of a face-on galaxy is a classical representation of the massive star formation rate per unit surface area. Here, we present a test for the degree of symmetry in this distribution, aimed at deciding whether this parameter shows a significant difference between barred and non-barred galaxies. The test consists in deriving the cross-correlation function of the Hα brightness as a function of curvilinear distance along pairs of opposed arms. In order to use the test, we first apply a geometrical unfolding technique. Here we explain this technique, and present the initial results of applying the test to NGC 157 and NGC 6764.

We have carried out optical and Far UV studies of the field around the EUV source EUVE J1027+323. We find two sources which contribute to this flux which are spatially unresolvable with EUVE. One is a non-cataloged QSO and one is a “hidden” hot white dwarf. Reasonable scenarios ascribe the majority of the flux to the white dwarf.