A near-infrared (J and K) survey of the LMC Bar West region was undertaken with CIRIM on the CTIO 1.5-m telescope to search for obscured carbon stars. A number of very red stars were detected, and from this list five highly reddened, ‘Obscured’ stars were identified. Subsequent to our survey we identified these sources in the 2MASS survey data. Using our J, K photometry as well as J, H, K from 2MASS, 8.28 µm from the MSX satellite, and L photometry from Phoenix on Gemini, we have measured the color temperature and flux of the detected obscured stars. None of these objects is as cool as the bright galactic enshrouded carbon star CW Leo, although the MSX survey does appear to detect objects similar to CW Leo. Using the Phoenix high-resolution infrared spectrograph on Gemini we have observed the first overtone CO spectra of four of the LMC obscured stars. All the spectra are those expected for obscured carbon stars, but a surprising variety of line profiles was found.

I point out that the Oosterhoff dichotomy for globular cluster and field RR Lyrae stars may place the strongest constraints so far on the number of dwarf spheroidal-like protogalactic fragments that may have contributed to the formation of the Galactic halo. The first calibration of the RR Lyrae period-luminosity relation in I, J, H, K taking evolutionary effects into account is provided. Problems in the interpretation of RR Lyrae light curves and evolutionary properties are briefly reviewed.

I have performed a detailed analysis of multiperiodic RR Lyr stars of the Galactic Bulge and the Small Magellanic Cloud. In the rich OGLE-II database on the Galactic Bulge objects I detected more than 2500 RR Lyr stars, with almost 600 of them exhibiting multiperiodic behavior of various, sometimes unique, kinds. Many of them can only be explained by excitation of nonradial modes. There are two major, striking differences between the two discussed stellar systems: the incidence rate of RRd double mode pulsators is over 30 times higher in the SMC than in the Galactic Bulge, and there are more than twice as many Blazhko stars in the Galactic Bulge as in the SMC.

The kinematical parameters of the local field RR Lyrae population and the zero point of the log P –〈MK〉 relation for these variables are inferred by applying the statistical parallax (maximum-likelihood) technique to a sample of 379 RR Lyrae stars with known periods, radial-velocities, metallicities, K-band photometry, and absolute proper motions on the ICRS system. Hipparcos, Tycho-2, SPM, UCAC1 and NPM1 were used as the sources of proper motions. The K-band magnitudes were adopted from the 2MASS All-Sky Data Release. The parameters of the velocity distribution are found to be (U0 = −13 ± 9, V0 = −41 ± 7, W0 = −19±4) kms−1, (σU = 66±9, σV = 47±7, σW = 23±5) km s−1 and (U0 = −11±10, V0 = −224±8, W0 = −8±6) km s−1 (σU = 158±9, σV = 95±5, σW = 88±5) km s−1 for the thick-disk (the purest disk sample, 56 stars) and halo (the purest halo sample, 264 stars) objects, respectively. The zero point of the infrared PL relation of Jones et al. (1992 – based on the results obtained using the Baade-Wesselink method) is confirmed: we find 〈MK〉 = −2.33⋅log PF−0.89±0.09, which is only brighter than found using the Baade-Wesselink method (Jones et al. 1992). A conversion of the resulting log P –〈MK〉 relation to V-band luminosities yields the metallicity-luminosity relation 〈MV〉 = +1.12 + 0.18 ⋅ [Fe/H] ± 0.10. Our results imply a solar Galactocentric distance of R0 = 7.8±0.4 kpc and an LMC distance modulus of DMLMC = 18.17 ±0.10 (cluster RR Lyraes) or DMLMC = 18.10±0.10 (field RR Lyraes), thereby favoring the so-called short distance scale.

We present first results concerning the detection of variable stars in the Carina dwarf Spheroidal from B, V images collected with the 4-m CTIO telescope. We show a sample of candidate variables spanning from the tip of the Red Giant Branch down to the Main Sequence turn off. Finally, we discuss the future photometric and spectroscopic developments of this project.

Masers are known to occur in circumstellar envelopes of AGB stars that are long-period variables and have entered the TP-AGB phase. The maser radiation is intrinsically weak and detection limits prevent us from seeing maser stars much beyond the Galactic Center. Very deep searches have led to the detection of a handful of maser stars in the Large Magellanic Cloud. Some 1000 stellar masers are known. They trace a population of stars with main sequence masses between 1 and 6 M⊙ and ages between 2 and 8 Gyr, the same population that is traced by Cepheids. Their distribution in our Galaxy is the same as that of the red giants, and therefore the stars trace the galactic bar. An outstanding feature is a small disk of radius 150 pc around the galactic center. The disk is in rapid, solid body rotation and leads to a good measurement of the mass density within that distance for Sgr A.

With a large number of newly detected red variables in globular clusters we construct a log P – K diagram of these stars and compare it with findings from the LMC. We show the existence of a relation between the location in log P – K diagram and the velocity amplitude in the near infrared.

Results obtained in the Magellanic Clouds using the latest near-IR DENIS survey are briefly reviewed. This sets the stage for a similar study of AGB stars in other galaxies in the Local Group and, in particular, in NGC 6822.

From photometric observations out to the tidal radii of the galaxies, we were able to identify hundreds of new carbon stars, to derive mean absolute magnitudes〈Mi〉, luminosity functions, and the spatial/radial distributions of the carbon stars in these galaxies. For each galaxy this new material will allow estimates of the tips of their RGBs to derive distance moduli, to derive C/M ratios of the AGB populations and bolometric magnitudes Mbol. At the end of our survey a comparison of all quantities of the late-type stars as a function of the properties of the host galaxies will be made possible.

The wavelike oscillations of the vertical scale height of the local population of classical Cepheids located at Galactocentric distances R0 – 1 kpc < Rg < R0 + 1 kpc is analyzed using Cepheid ages computed in terms of evolutionary models of Pols et al. (1998) with and without the allowance for convective overshooting. The resulting periods of vertical oscillations of stars about the galactic plane are found to be PZ = 74 ± 2 Myr and PZ = 104 ± 2 Myr for standard models and models with overshooting, respectively. If interpreted as a manifestation of vertical virial oscillations, the pattern found implies local mass density values of ρstd = 0.118 ± 0.007 M⊙ pc−3 and ρovs = 0.060 ± 0.004 M⊙ pc−3, respectively. The latter value is totally incompatible with recent estimates based on Hipparcos data and the former value, combined with recent estimates of the local density of visible matter, sets an upper limit of 0.023 M⊙ pc−3 for the local density of dark matter.

We present the first CCD photometric observations of the northern open cluster NGC 2126. Data were taken on eight nights in 2002 February and December with a total time span of ~57 hours. We have discovered six new variable stars and have estimated the main characteristics of the cluster.

Through time-series CCD photometry of the globular cluster NGC 5466, we found three double-radial-mode SX Phe stars, all of which are consistent with the theoretical period ratio of the first overtone mode to the fundamental mode (P1H/PF); their period ratios are 0.7825, 0.7826 and 0.7919, respectively. We also detected a double-radial-mode SX Phe star in M71. Its period ratio is 0.781, which is also consistent with the theoretical value.

The light curve characteristics of a homogeneous sample of variables in M3 are studied in detail. Accurate light curves and mean magnitudes of about 100 RRab and 50 RRc stars which do not show any type of modulation are analyzed. According to their mean magnitudes and Fourier parameters the variables can be sorted into four groups, representing different stages of the horizontal branch stellar evolution.

The status of the WWW-based Fourier Coefficient web site is presented. Currently the database has coefficients for not only galactic field variables, but also those found in globular clusters and other galaxies, including the Magellanic Clouds. The database can be used to show various correlations between physical characteristics of the stars and the coefficients, as well as inter-relationships between the coefficients themselves. The database is accessible at http://nitro9.earth.uni.edu/fourier/.

Fourier coefficients have been derived for the V and R light curves of 330 bona fide RR Lyrae first-overtone (RR1) pulsators in 16 MACHO fields near the bar of the LMC. We use the Fourier phase parameter ɸ31 and log P values to select a subsample of these stars which are similar to the RR1s in the Galactic globular cluster M5. Assuming that the M5-like stars in the LMC have absolute magnitudes comparable to the HB stars in M5, we use independent studies to derive their mean absolute V magnitude and compute a visual distance modulus of μLMC = 18.43 ± 0.06 (statistical) ±0.16 (systematic). By selecting stars on the basis of their light curve parameters, we are able to derive a distance modulus that does not depend on the somewhat poorly determined Mv – [Fe/H] relation for RR Lyr stars.

Some 34 novae have been discovered in the LMC and 14 in the SMC. Historically, the novae seemed to avoid the central bar of the LMC and the main body of the SMC, but with the novae discovered in the past two decades a different picture emerges. The more dramatic situation exists in the SMC where all seven of the most recent novae have occurred in or very near the main body. Indications are that the age of the LMC bar is around 5Gyr (Smecker-Hane et al. 2002), certainly old enough to breed novae. Perhaps the puzzle now is why there have been so many novae in the disk component of the LMC where many HII regions are found.

We present U, B, V, I (SUSI@NTT) and J,Ks (SOFI@NTT) photometry of the Large Magellanic Cloud (LMC) cluster Reticulum. The observing strategy and data reduction (DAOPHOTII/ALLFRAME) allowed us to reach an accuracy of the order of 0.01 – 0.03 mag in all the bands at limiting magnitudes typical of RR Lyrae stars. Reticulum hosts a sizable sample of RR Lyrae stars (32), and we supply an accurate distance estimate using the RR Lyrae K-band Period-Luminosity-Metallicity (PLZK) relation. This method presents several advantages when compared with the MV vs [Fe/H] relation, since it is only marginally affected by off-ZAHB evolutionary effects and reddening corrections.

In this paper, we give an updated overview of the observed characteristics of g-mode pulsations in slowly pulsating B stars. These characteristics are based on the combined results of linear nonadiabatic analysis of the oscillations and a photometric and spectroscopic mode identification for a sample of 13 members. For 4 stars, at least one mode is stable in all the considered theoretical models.

We present a method for the analysis of latitude distribution associated with temperature and/or velocity perturbations of the stellar surface due to non-radial pulsation (NRP) modes in rapidly rotating B stars. The technique is applied together with Fourier Doppler Imaging (FDI) to high resolution and high signal-to-noise ratio spectroscopic observations of ϵ Per. The main advantage of this approach is that it decomposes complex multi-periodic line profile variations into single components, allowing the detailed analysis of each mode separately. We study the 10.6-d−1 frequency that is particularly important for modal analysis of non-radial pulsations in the star.

We discuss spectroscopic observations of pulsations in the roAp stars γ Equ and HR 1217. In both stars we observe strong variations of rare-earth lines and detect running magneto-acoustic waves, but do not find evidence for a standing pulsational wave. In γ Equ we find strong pulsational variations across line profiles, characteristic of l ≥ 2 modes.