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Late-type stars are generally characterized by the chromospheric structure showing active phenomena observable by the formation of emission lines and emission of X-ray and UV radiations. In the optical region, most ubiquitous emission lines are CaII H, K lines, while Hα line appears in fully developed chromospheres. In this section we consider the basic chromospheric activities by focusing to the CaII H, K emission lines.

We present "On The Fly" maps of the CO(1-0) and CO(2-1) emission covering a 10' X 10' region of the NGC 6946. Using our CO maps and archival VLA HI observations we create a total gas surface density map, Sigma_gas, for NGC 6946. The predominantly molecular inner gas disk transitions smoothly into an atomic outer gas disk, with equivalent atomic and molecular gas surface densities at R = 3.5' (6 kpc). We estimate that the total H2 mass is 3 X 10^9 Mo, roughly 1/3 of the interstellar hydrogen gas mass, and about 2% of the dynamical mass of the galaxy at our assumed distance of 6 Mpc. The value of the CO(2-1)/CO(1-0) line ratio ranges from 0.35 to 2; 50% of the map is covered by very high ratio, >1, gas. The very high ratios are predominantly from interarm regions and appear to indicate the presence of wide-spread optically thin gas. Star formation tracers are better correlated with the total neutral gas disk than with the molecular gas by itself implying SFR is proportional to Sigma_gas. Using the 100 FIR and 21 cm continuum from NGC 6946 as star formation tracers, we arrive at a gas consumption timescale of 2.8 Gyr, which is relatively uniform across the disk. The high star formation rate at the nucleus appears to be due to a large accumulation of molecular gas rather than a large increase in the star formation efficiency. The mid-plane gas pressure in the outer (R > 10 kpc) HI arms of NGC 6946 is close to the value at the radial limit (10 kpc) of our observed CO disk. If the mid-plane gas pressure is a factor for the formation of molecular clouds, these outer HI gas arms should contain molecular gas which we do not see because they are beyond our detection limit.

Using imaging data from the SDSS survey, we present the g' and r' radial stellar light distribution of a complete sample of ~90 face-on to intermediate inclined, nearby, late-type (Sb-Sdm) spiral galaxies. The surface brightness profiles are reliable (1sigma uncertainty less than 0.2 mag) down to mu=~27magsqarcsec. Only ~10% of all galaxies have a normal/standard purely exponential disk down to our noise limit. The surface brightness distribution of the rest of the galaxies is better described as a broken exponential. About 60% of the galaxies have a break in the exponential profile between ~1.5-4.5 times the scalelength followed by a downbending, steeper outer region. Another ~30% shows also a clear break between ~4.0-6.0 times the scalelength but followed by an upbending, shallower outer region. A few galaxies have even a more complex surface brightness distribution. The shape of the profiles correlates with Hubble type. Downbending breaks are more frequent in later Hubble types while the fraction of upbending breaks rises towards earlier types. No clear relation is found between the environment, as characterised by the number of neighbours, and the shape of the profiles of the galaxies., LaTeX, 69 pages, 213 (very low resolution) figures, A&A accepted. Second version to match the accepted one including all referee's comments. Version with full resolution figures (highly recommended, but with 7.6MB) available at http://www.astro.rug.nl/~pohlen/pohlenSDSS.pdf

The J=2-1, v=0 emissions of 28Si0,29Si0, and 30Si0 from three late-type stars were simultaneously observed with the Nobeyama 45-m telescope in January 1987. The relative intensities of (29Si0 ) / (30Si0 ) were measured to be 2.4 for χ Cyg, 1.5 for NML Tau, and 2.9 for V1111 Oph. These values are lower limits for the relative isotope abundance of (29Si) / [30Si) , and are larger than the terrestrial value of 1.51. Recent theoretical studies suggest that hydrostatic nucleosysnthesis and supernova explosions result in smaller values of (29Si) / (30Si) than solar. These models cannot explain the observed excess of 29Si.

Clusters of galaxies are believed to be at the intersections of cosmological filaments and to grow by accreting matter from these filaments. Such continuous infall has major consequences not only on clusters but also on the physics of cluster galaxies. Faint galaxies are particularly interesting as they are very sensitive to environmental effects, and may have a different behaviour from that of bright galaxies. The aim of this paper is to sample the Coma cluster building history, based on the analysis of galaxy luminosity functions and red sequences in the Color Magnitude Relation down to faint magnitudes, which are privileged tools for this purpose. The present analysis is based on deep (R~24), wide (~0.5 deg2) multiband (BVRI Vega system) images of the Coma cluster obtained with the CFH12K camera at the CFHT. We have derived LFs and CMRs in twenty 10x10 arcmin2 regions and in larger regions. In all photometric bands, we found steeply rising LFs in the north-northeast half of the cluster (due to early type galaxies at bright magnitudes and due to late type galaxies at the faint end), and much flatter LFs in the south-southwest region. Although the fine behaviour of the CMR RS is different in these two regions, a good agreement is found in general between the RS computed for faint and for bright galaxies. All these results can be interpreted consistently in the framework of the building up process previously proposed. The Northern Coma area is a relatively quiescent region while the southern area experiences several infalls., Comment: To be published in A&A, several figures in jpg format, full resolution figures and paper available at http://cencosw.oamp.fr/ under the Coma page. The lacking figures are available at the same adress. Updated CFHT acknowledgements and aa format

ABRIDGED: We use HSTACS and NICMOS imaging to study the structure and colors of a sample of nine late-type spirals. We find: (1) A correlation between bulge and disks scale-lengths, and a correlation between the colors of the bulges and those of the inner disks. Our data show a trend for bulges to be more metal-enriched than their surrounding disks, but otherwise no simple age-metallicity connection between these systems; (2) A large range in bulge stellar population properties, and, in particular, in stellar ages. Specifically, in about a half of the late-type bulges in our sample the bulk of the stellar mass was produced recently. Thus, in a substantial fraction of the z=0 disk-dominated bulged galaxies, bulge formation occurs after the formation/accretion of the disk; (3) In about a half of the late-type bulges in our sample, however, the bulk of the stellar mass was produced at early epochs; (4) Even these "old" late-type bulges host a significant fraction of stellar mass in a young(er) c component; (5) A correlation for bulges between stellar age and stellar mass, in the sense that more massive late-type bulges are older than less massive late-type bulges. Since the overall galaxy luminosity (mass) also correlates with the bulge luminosity (mass), it appears that the galaxy mass regulates not only what fraction of itself ends up in the bulge component, but also "when" bulge formation takes place. We show that dynamical friction of massive clumps in gas-rich disks is a plausible disk-driven mode for the formation of "old" late-type bulges. If disk evolutionary processes are responsible for the formation of the entire family of late-type bulges, CDM simulations need to produce a similar number of initially bulgeless disks in addition to the disk galaxies that are observed to be bulgeless at z=0., Comment: ApJ in press; paper with high resolution figures available at http://www.exp-astro.phys.ethz.ch/carollo/carollo1_2006.pdf; B, I, and H surface brightness profiles published in electronic tabular form

For a sample of 43 nearby, late-type galaxies, we have investigated the radial variation of both the current star formation rate and the dust-induced UV light attenuation. To do this we have cross-correlated IRAS images and GALEX observations for each of these galaxies, and compiled observations of the gas (CO and HI) and metal-abundance gradients found in the literature. We find that attenuation correlates with metallicity. We then use the UV profiles, corrected for attenuation, to study several variants of the Schmidt law and conclude that our results are compatible with a simple law similar to the one of Kennicutt but extending smoothly to lower surface densities, but with considerable scatter. We do not detect an abrupt break in the UV light at the threshold radius derived from H-alpha data (at which the H-alpha profile shows a break and beyond which only a few HII regions are usually found). We interpret the H-alpha sudden break not as a change in the star formation regime (as often suggested) but as the vanishingly small number of ionizing stars corresponding to low levels of star formation., 28 pages, 9 figures, accepted for the GALEX special issue of ApJS. For a version with high-resolution figures, see http://www.oamp.fr/boissier/preprint/preprint.html

We continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

We report the case of a 69-year-old man with a late type 1b endoleak due to proximal migration of both iliac limbs 5 years after endovascular repair of an abdominal aortic aneurysm. The endovascular method used to correct bilaterally this condition is described. Final angiographic control shows patency of the stent-graft without signs of endoleak.

We present a new formula for absolute magnitude determination for late-type dwarf stars as a function of (g-r) and (r-i) for Sloan photometry. The absolute magnitudes estimated by this approach are brighter than those estimated by colour-magnitude diagrams, and they reduce the luminosity function rather close to the luminosity function of Hipparcos., 11 pages, 9 figures and 5 tables, accepted for publication in AN

CCD observations of stars in the young cluster IC 348 were obtained from 2004 August to 2005 January with a 0.45 m ROTSEIIId robotic reflecting telescope at the Turkish National Observatory site, Bakirlitepe, Turkey. The timing analysis of selected stars whose X-Ray counterpart were detected by Chandra X-Ray Observatory were studied. The time series of stars were searched for rotational periodicity by using different period search methods. 35 stars were found to be periodic with periods ranging from 0.74 to 32.3 days. Eighteen of the 35 periodic stars were new detections. Four of the new detections were CTTSs and the others were WTTSs and G type (or unknown spectral class) stars. In this study, we confirmed the stability of rotation periods of TTauri stars. The periods obtained by Cohen et al. and us were different by 1%. We also confirmed the 3.24 h pulsation period of H254 which is a delta Scuti type star as noted by Ripepi et al. but the other periods detected by them were not found. We examined correlation between X-ray luminosity and rotational period of our sample of TTSs. There is a decline in the rotational period with X-ray luminosity for late type TTSs., Comment: 15 pages, 14 figures, accepted for publication in Astronomical Journal

The role of magnetic field in late type stars such as proto-planetary and planetary nebulae (PPNe/PNe), is poorly known from an observational point of view. We present submillimetric observations realized with the Submillimeter Array (SMA) which unveil the dust continuum polarization in the envelopes of two well known PPNe: CRL 618 and OH 231.8+4.2. Assuming the current grain alignment theory, we were then able to trace the geometry of the magnetic field.

HD 202850 is a late B-type supergiant. It is known that photospheric lines of such stars vary. Due to macroturbulence the lines are much wider than expected. Macroturbulence has been linked to stellar pulsations. It has been reported that there are several B supergiants that undergo pulsations. In our previous work, we detected a pulsational period of 1.59 hours in this object from data taken with the Ondrejov 2-m telescope. We continued to investigate this object and we took several time series with the DAO 1.2-m telescope. Our new data suggest that there may be some additional pulsational periods in this star. We present our new results in this poster., Comment: 2 pages, 1 figure, small corrections performed, published in IAU Symp. 301: Precision Asteroseismology, eds. J. Guzik, W. Chaplin, G. Handler, A. Pigulski, p. 503-504

We present results of an investigation of the X-ray properties, age distribution, and kinematical characteristics of a high-galactic latitude sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS). The sample comprises 254 RASS sources with optical counterparts of spectral types F to M distributed over six study areas located at |b| >= 20 degr, and DEC >= -9 degr. A detailed study was carried out for the subsample of ~200 G, K, and M stars. Lithium abundances were determined for 179 G-M stars. Radial velocities were measured for most of the 141 G and K type stars of the sample. Combined with proper motions these data were used to study the age distribution and the kinematical properties of the sample. Based on the lithium abundances half of the G-K stars were found to be younger than the Hyades (660 Myr). About 25% are comparable in age to the Pleiades (100 Myr). A small subsample of 10 stars is younger than the Pleiades. They are therefore most likely pre-main sequence stars. Kinematically the PMS and Pleiades-type stars appear to form a group with space velocities close to the Castor moving group but clearly distinct from the Local Association., accepted for publication in Astronomy & Astrophysics

We present Echelle spectra of 91 late-type dwarfs, of spectral types from F to M and of different levels of chromospheric activity, obtained with the 2.15 m telescope of the CASLEO Observatory located in the Argentinean Andes. Our observations range from 3890 to 6690 Å at a spectral resolution from 0.141 to 0.249 Å per pixel (R = λ/δλ ≈ 26 400). The observations were flux calibrated with the aid of long slit spectra. A version of the calibrated spectra is available via the World Wide Web†. Fil: Cincunegui, Carolina Cecilia. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Mauas, Pablo Jacobo David. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina

The Tully-Fisher Relationship (TFR) is utilized to identify anomalous redshifts in normal spiral galaxies. Three redshift anomalies are identified in this analysis: (1) Several clusters of galaxies are examined in which late type spirals have significant excess redshifts relative to early type spirals in the same clusters, (2) Galaxies of morphology similar to ScI galaxies are found to have a systematic excess redshift relative to the redshifts expected if the Hubble Constant is 72 km s-1 Mpc-1, (3) individual galaxies, pairs, and groups are identified which strongly deviate from the predictions of a smooth Hubble flow. These redshift deviations are significantly larger than can be explained by peculiar motions and TFR errors. It is concluded that the redshift anomalies identified in this analysis are consistent with previous claims for large non-cosmological (intrinsic) redshifts., Accepted for publication at Astrophysics&Space Science. 36 pages including 8 tables and 7 figures

A new volume-limited sample of 84 isolated pairs of galaxies has been selected from the UZC catalogue. Galaxies in pairs are brighter than $M_{Zw}-5log h =-18.9$. The projected separation between pair members is $r < 200 h^{-1}$ kpc, the isolation criterion requires the pair to have no further companion within a $R=1 h^{-1}$ Mpc distance. Morphological classification for both members is available for 57 pairs. Out of these, 9 are early-type (E+E) pairs, 29 late type (S+S) pairs, and 19 mixed (E+S) pairs. We find a deficit of luminous dominants among E+E and E+S pairs relative to S+S pairs, while the distance between pair members is statistically undistinguishable. However, among the 12 pairs that are not only close but also luminous, the fraction of E+E and S+S pairs is 8% and 83% respectively. This result is consistent with star-formation being enhanced in S+S pairs (but not in spirals in S+E pairs) in extremely close isolated pairs.

We present a compilation and study of DENIS, 2MASS, ISOGAL, MSX and IRAS 1--25 micron photometry for a sample of 441 late-type stars in the inner Galaxy, which we previously searched for 86 GHz SiO maser emission (Messineo et al.2002). The comparison of the DENIS and 2MASS J and Ks magnitudes shows that most of the SiO targets are indeed variable stars. The MSX colours and the IRAS [12]-[25] colour of our SiO targets are consistent with those of Mira type stars with dust silicate feature at 9.7 micron feature in emission, indicating only a moderate mass-loss rate., 16 pages, 17 figures. Accepted for publication in A&A

We compute the rate of supernovae (SNe) of different types along the Hubble sequence normalized to the near-infrared luminosity and to the stellar mass of the parent galaxies. This is made possible by the new complete catalog of near-infrared galaxy magnitudes obtained by 2MASS. We find that the rates of all SN types, including Ia, Ib/c and II, show a sharp dependence on both the morphology and the (B-K) colors of the parent galaxies and, therefore, on the star formation activity. In particular we find, with a high statistical significance, that the type Ia rate in late type galaxies is a factor ~20 higher than in E/S0. Similarly, the type Ia rate in the galaxies bluer than B-K=2.6 is about a factor of 30 larger than in galaxies with B--K>4.1. These findings can be explained by assuming that a significant fraction of Ia events in late Spirals/Irregulars originates in a relatively young stellar component., 10 pages, A&A, in press

We have used UV (FOCA) and FIR (IRAS) images of six nearby late type galaxies to study the radial variation of the UV extinction (deduced from the FIR/UV ratio). We compare the UV extinction gradient with other extinction indicators (Balmer decrement) and search for a relation between the extinction, the metallicity and the gas surface density among our galaxies. We detect in our small sample a clear relation between extinction and metallicity. These observed relations are used to calibrate an empirical recipe useful for extinction correction in the UV, visible and near-infrared images of late type galaxies., 17 pages, 13 figures (higher resolution images available on request). Accepted in A&A (in press)

We test our knowledge of the atomic opacity in the solar UV spectrum. Using the atomic data compiled in Paper I from modern, publicly available, databases, we perform calculations that are confronted with space-based observations of the Sun. At wavelengths longer than about 260 nm, LTE modeling can reproduce quite closely the observed fluxes; uncertainties in the atomic line data account fully for the differences between calculated and observed fluxes. At shorter wavelengths, departures from LTE appear to be important, as our LTE and restricted NLTE calculations differ. Analysis of visible-near infrared Na I and O I lines, two species that produce a negligible absorption in the UV, shows that observed departures from LTE for theses species can be reproduced very accurately with restricted (fixed atmospheric structure) NLTE calculations., 13 pages, 11 figures, to appear in ApJ

The size and variability of the photospheres of several late-type stars has been probed using 11 micron heterodyne interferometry. High resolution observations performed during the years 1999 - 2001 yielded diameter measurements accurate to about 1% for α Ori and o Cet, an supergiant and a mira variable. Narrow bandwidths (0.17 cm -1 ) and high resolution spectra were used to avoid molecular lines. Observations were made at several different wavelengths, sometimes purposely overlapping an observed spectral feature. In all cases, the 11 micron sizes are larger than previously measured visible and near-infrared diameters. The discrepancies will be discussed. In addition, a variation of the diameter of Mira with phase has been observed.

We have investigated 1008 objects in the area of five intermediate age open clusters (NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756) via the narrow band Delta a-system. The detection limit for photometric peculiarity is very low (always less than 0.009mag) due to the high number of individual frames used (193 in total). We have detected six peculiar objects in NGC 6705 and NGC 6756 from which one in the latter is almost certainly an unreddened late type foreground star. The remaining five stars are probably cluster members and bona fide chemically peculiar objects (two are lambda Bootis type candidates). Furthermore, we have investigated NGC 3114, a cluster for which already photoelectric Delta a-measurements exist. A comparison of the CCD and photoelectric values shows very good agreement. Again, the high capability of our CCD Delta a-photometric system to sort out true peculiar objects together with additional measurements from broad or intermediate band photometry is demonstrated., Comment: 6 pages, 2 figures, accepted by A&A

We carry out an analysis of the Mg II 2796.34 A emission line in RS CVn stars and make a comparison with the normal stars studied in a previous paper (Paper I). The sample of RS CVn stars consists of 34 objects with known HIPPARCOS parallaxes and observed at high resolution with IUE. We confirm that RS CVn stars tend to possess wider Mg II lines than normal stars having the same absolute visual magnitude. However, we could not find any correlation between the logarithmic line width log Wo and the absolute visual magnitude Mv (the Wilson--Bappu relationship) for these active stars, contrary to the case of normal stars addressed in Paper I. On the contrary, we find that a strong correlation exists in the (Mv, log L) plane (L is the absolute flux in the line). In this plane, normal and RS CVn stars are distributed along two nearly parallel straight lines with RS CVn stars being systematically brighter by about 1 dex. Such a diagram provides an interesting tool to discriminate active from normal stars. We finally analyse the distribution of RS CVn and of normal stars in the (log L, log Wo) plane, and find a strong linear correlation for normal stars, which can be used for distance determinations., Comment: 10 pages, 7 figures, latex, to be published in A&A

Observations of the standard late type M8 star LHS 2397aA were obtained at the ESO-VLT 8m telescope ``Yepun'' using the NAOS/CONICA Adaptive Optics facility. The observations were taken during the NACO commissioning, and the infrared standard star LHS 2397aA was observed in the H, and Ks broad band filters. In both bands the brown dwarf companion LHS2397aB was detected. Using a program recently developed (Bouy et al., 2003) for the detection of stellar binaries we calculated the principal astrometric parameters (angular binary separation and position angle P.A.) and the photometry of LHS 2397aA and LHS 2397aB. Our study largely confirms previous results obtained with the AO-Hokupa'a facility at Gemini-North (Freed et al., 2003); however a few discrepancies are observed., 5 pages

Using the VLBA, we observed the SiO J=l-0 masers lines at the v = 1 and v = 2 states in the Orion KL. The spatial distribution of the Orion KL shows no regularity in two lines, though supergiant VY CMa shows good correlation. The environment where the SiO masers generate is different between late type stars and star forming regions

We present observations of 86 GHz (J=2-l, v=l) SiO maser emission in the Inner Galaxy. Using the IRAM 30m telescope, we targeted late-type stars selected from the ISOGAL and MSX catalogues, in order to measure radial velocities of a large number of stars. Our 255 new measurements double the number of maser line-of-sight velocities known toward the inner Galaxy. Combining our measurements with those from other surveys, in particular OH maser surveys, will allow a kinematic analysis of the stellar orbits in the inner Galaxy. Analyzing the colours and luminosities of OH and SiO maser emitters also yields new clues on the conditions under which different masers may occur

We study the mass loss phenomenon which is though to be generally seen in the evolution of late type stars. We are using radio interferometry European VLBI Network (EVN) and Multi-Element Radio Lined Network (MERLIN) to study maser emission from gas molecules of H2O and OH. This enable us to obtain 10-30 mas resolution images of mass-loss in AGB stars

We present Very Large Array (VLA) observations of 43 GHz (J=1-0, v=0 and v=1) SiO maser emission in a sub-sample of late-type stars with relatively strong (> 0.5 Jy) 86 GHz SiO masers in the Inner Galaxy

Using an evolutionary population synthesis code, we modeled the global emission of X-ray binaries in late-type galaxies, its relations with other physical properties (i.e., optical luminosity, stellar mass, etc.) of the galaxies, and their evolution with redshift over the cosmic history, which may be investigated further by future high-resolution X-ray and optical observations.

We introduced our preliminary results of chromospheric activity of late-type stars based on the stellar spectrum of the pilot survey of the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST, also called Guo Shou Jing telescope). We have found 1151 active M stars from 17471 M samples using the chromospheric active indicator of the Hα line.

We present 86 GHz (v = 1, J = 2 -1) SiO maser line observations with the IRAM 30-m telescope of a sample of 441 late-type stars in the Inner Galaxy (-4 degr < l < +30 degr). These stars were selected on basis of their infrared magnitudes and colours from the ISOGAL and MSX catalogues. SiO maser emission was detected in 271 sources, and their line-of-sight velocities indicate that the stars are located in the Inner Galaxy. These new detections double the number of line-of-sight velocities available from previous SiO and OH maser observations in the area covered by our survey and are, together with other samples of e.g. OH/IR stars, useful for kinematic studies of the central parts of the Galaxy., 15 pages, 12 figures, accepted by A&A Journal

We present a calibration of the massive star formation rate vs. [CII] luminosity relation based on a sample of nearby, late-type galaxies observed with ISO-LWS and imaged in the Halpha+[NII] line. The relation holds for far-IR luminosities 10^8 < L_{FIR} < 10^{10.5} L (solar units). The derived star formation rates have an uncertainty of about a factor of 10. Part of this uncertainty is due to the different mix of contributions to the [CII] emission from the different components of the interstellar medium in individual galaxies, as discussed in an appendix., Accepted for publication on Astronomy & Astrophysics

Progress in observational techniques (i.e. high S/N spectroscopy) and modelling (e.g. RE models including convection, nonLTE codes, accurate atomic data) make significant to carry to extremes the numerical fit of a portion of the stellar spectrum and try to interpret the residual differences between calculations and observations in terms of stellar characteristics new respect to the employed model.We have started to apply this synthesis method to a set of high resolution, high S/N spectra of late-type dwarfs in the region of the Na I D lines, obtained at ESO with the 1.4m CAT on May 1989 (Franchini et al. 1992). The dwarf stars are modelled in radiative equilibrium (RE), and the Na I D line synthesis accounts for nonLTE and blend effects.

We investigate the oxygen and nitrogen abundance distributions across the optical disks of 130 nearby late-type galaxies using around 3740 published spectra of HII regions. We use these data in order to provide homogeneous abundance determinations for all objects in the sample, including HII regions in which not all of the usual diagnostic lines were measured. Examining the relation between N and O abundances in these galaxies we find that the abundances in their centres and at their isophotal R_25 disk radii follow the same relation. The variation in N/H at a given O/H is around 0.3 dex. We suggest that the observed spread in N/H may be partly caused by the time delay between N and O enrichment and the different star formation histories in galaxies of different morphological types and dimensions. We study the correlations between the abundance properties (central O and N abundances, radial O and N gradients) of a galaxy and its morphological type and dimension., 77 pages, 6 figures, 3 tables, accepted to the AJ

We present temperature maps of the active late-type giant FK Com which exhibit the first imagining record of the ``flip-flop'' phenomenon in a single star. The phenomenon, in which the main part of the spot activity shifts 180 degrees in longitude, discovered a decade ago in FK Com, was reported later also in a number of RS CVn binaries and a single young dwarf. With the surface images obtained right before and after the ``flip-flop'', we clearly show that the ``flip-flop'' phenomenon in FK Com is caused by changing the relative strengths of the spot groups at the two active longitudes, with no actual spot movements across the stellar surface, i.e. exactly as it happens in other active stars., 4 pages, accepted by A&A Letters

We have measured the equivalent width (EW) of the K I 7699 A line in a sample of G and K-type members of the ~35 Myr old cluster IC 2602 for which a dispersion in Li EWs had been reported by previous studies. Active cluster stars with 0.75 < (B-V)o < 1 are characterized by a dispersion in the EW of the K I 7699 A, while earlier and later-type stars do not show any significant scatter. Cluster stars at all colors show potassium EW excesses with respect to field inactive stars; furthermore, a statistically significant relationship is found between differential potassium EWs and log Lx/Lbol ratios, indicating that the EWs of the potassium feature are altered by activity. Our results suggest that the dispersion in Li EWs observed among cluster stars later than (B-V)o ~ 1 cannot be fully explained by the effects of activity. No final conclusion can instead be drawn for earlier-type stars., accepted by A&A

The RS CVn type eclipsing binary MM Herculis was observed photo-electrically using B, V and R filters in 1998 and 1999 and the light and colour curves were obtained. Spectroscopic observations were carried out in 1999. The new light and colour curves are anti-correlated with the observations of 1997, i.e. the system is bluer when it is faintest. the variations of the brightnesses at each special phase (0.0, 0.25, 0.5, and 0.75) show an almost cyclic change with a period of about 6 years. This value is in good agreement with the migration periods of the spots suggested by us previously. The outside-of-eclipse wave in the light curve shows a minimum at phase ?0.50, and the mean colour of the system is the bluest at the same phase. When the spots located on the cooler component are seen around phase 0.50, the amplitude of the light variation outside eclipse is larger than the others. Such variation may be caused by the effect of the hotter component. Spectroscopic observations of the system were carried out in the spectral range 5860-6700. Å. The subtraction of a "synthetic" spectrum, built up with spectra of inactive standard stars, allows us to detect an H? emission excess only from the cool component. New radial velocity measurements of the system were obtained and analyzed for the orbital parameters.

We provide detailed abundance analyses of 8 candidate super-metal-richstars. Five of them are confirmed to have [Fe/H]>0.2 dex, thegenerally-accepted limit for super-metal-richness. Furthermore, wederive abundances of several elements and find that the stars followtrends seen in previous studies of metal-rich stars. Ages are estimatedfrom isochrones and velocities calculated. We find that there do existvery metal-rich stars that are older than 10 Gyr. This is contrary towhat is found in several recent studies of the galactic age-metallicityrelation. This is tentative evidence that there might not exist aone-to-one relation between age and metallicity for all stars. This isnot surprising considering the current models of the independentevolution of the different galactic components. We also find that onestar, HD 182572, could with ~ 75% chance be a thick disk star with, forthe thick disk, an extremely high metallicity at 0.34 dex. This star is,intriguingly, also somewhat enhanced in the alpha -elements. Based onobservations obtained at the McDonald Observatory.} (Less)

The Local Association or Pleiades moving group (MG) seems to consist of a reasonably coherent kinematic stream of young stars with embedded clusters and associations. The age of the stars in this association range from about 20 to 150 Myr. Evidences have been found that X-ray and EUV selected active stars and lithium-rich stars are member of this association. Recently, several studies using extended samples of stars (mainly early-type stars) with known radial velocities and astrometric data taken from Hipparcos not only confirm the existence of this moving group, but also detect finer structures.

In the framework of our ongoing study of late type visual binaries with variable components we present the first orbits for a well known flare star CR Dra. Its apparent visual brighness V = 9.96 and spectral type Ml Ve. With the Hipparcos parallax 0″.048 ± 0″.00116 we obtain its distance 21.3 pc.

We present narrowband-M photometry of nine low-mass dwarfs with spectral types ranging from M2.5 to L0.5. Combining the (L'-M') colours derived from our observations with data from the literature, we find colours consistent with a Rayleigh-Jeans flux distribution for spectral types earlier than M5, but enhanced F_3.8/F_4.7 flux ratios (negative (L'-M') colours) at later spectral types. This probably reflects increased absorption at M' due to the CO fundamental band. We compare our results against recent model predictions and briefly discuss the implications., Comment: accepted for the Astronomical Journal

The light curves of 19 NCBs, whose X-ray luminosities are greater than those of normal late type main-sequence stars, have been analyzed by the spot model for their magnetic activities. 14 systems have a cool spot while one system has a hot spot on the secondary system. Their chromospheric activities have been investigated by measureing Mg II emissionline of the IUE high resolution spectra.

Stellar kinematic groups (or Moving Groups, MG), are kinematically coherent groups of stars that share a common origin. We have compiled (see Montes 2000, these Proceedings) a sample of late-type stars, candidate members of different young stellar kinematic groups (Local Association (20 – 150 Myr), Ursa Mayor (300 Myr), Hyades (600 Myr), IC 2391 (35 Myr) and Castor (200 Myr)).