We report the result of our near-infrared observations (JHKs) for type II Cepheids (including possible RV Tau stars) in galactic globular clusters. We detected variations of 46 variables in 26 clusters (10 new discoveries in seven clusters) and present their light curves. Their periods range from 1.2 d to over 80 d. They show a well-defined period-luminosity relation at each wavelength. Two type II Cepheids in NGC6441 also obey the relation if we assume the horizontal branch stars in NGC6441 are as bright as those in metal-poor globular clusters in spite of the high metallicity of the cluster. This result supports the high luminosity which has been suggested for the RR Lyr variables in this cluster. The period-luminosity relation can be reproduced using the pulsation equation (P sqrt(rho)=Q) assuming that all the stars have the same mass. Cluster RR Lyr variables were found to lie on an extrapolation of the period-luminosity relation. These results provide important constraints on the parameters of the variable stars. Using Two Micron All-Sky Survey (2MASS) data, we show that the type II Cepheids in the Large Magellanic Cloud (LMC) fit our period-luminosity relation within the expected scatter at the shorter periods. However, at long periods ($P>40$ d, i.e. in the RV Tau star range) the LMC field variables are brighter by about one magnitude than those of similar periods in galactic globular clusters. The long-period cluster stars also differ from both these LMC stars and galactic field RV Tau stars in a colour-colour diagram. The reasons for these differences are discussed.Comment: 13 pages, 8 figures, Accepted for publication in MNRA

We present the result of a near-infrared (JHK S ) survey along the Galactic plane, −10. • 5 ≤ l ≤ 10. • 5 and b = +1 • , with the IRSF 1.4m telescope and the SIRIUS camera. K S vs. H − K S color-magnitude diagrams reveal a well-defined population of red clump (RC) stars whose apparent magnitude peak changes continuously along the Galactic plane, from K S = 13.4 at l = −10 • to K S = 12.2 at l = 10 • after dereddening. This variation can be explained by the bar-like structure found in previous studies, but we find an additional inner structure at | l | 4 • , where the longitude -apparent magnitude relation is distinct from the outer bar, and the apparent magnitude peak changes by only ≈ 0.1 mag over the central 8 • . The exact nature of this inner structure is as yet uncertain.

We present a near-infrared ($JHK_{\rm s}$) photometric catalog, including 14811185 point sources for a 40 deg$^2$ area of the Large Magellanic Cloud, 2769682 sources for an 11 deg$^2$ area of the Small Magellanic Cloud, and 434145 sources for a 4 deg$^2$ area of the Magellanic Bridge. The 10$\sigma$ limiting magnitudes are 18.8, 17.8, and 16.6 mag at $J, H$, and $K_{\rm s}$, respectively. The photometric and astrometric accuracies for bright sources are 0.03–0.04 mag and 0$\rlap {.}{^{\prime\prime}}$1, respectively. Based on the catalog, we also present (1) spatial distributions, (2) luminosity functions, (3) color–color diagrams, and (4) color–magnitude diagrams for point sources toward the Magellanic Clouds.

[1] We report the observation of two stellar occultations by Titan on 14 November 2003, using stations in the Indian Ocean, southern Africa, Spain, and northern and southern Americas. These occultations probed altitudes between $550 and 250 km ($1 to 250 mbar) in Titan's upper stratosphere. The light curves reveal a sharp inversion layer near 515 ± 6 km altitude (1.5 mbar pressure level), where the temperature increases by 15 K in only 6 km. This layer is close to an inversion layer observed fourteen months later by the Huygens HASI instrument during the entry of the probe in Titan's atmosphere on 14 January 2005 [Fulchignoni et al., 2005]. Central flashes observed during the first occultation provide constraints on the zonal wind regime at 250 km, with a strong northern jet ($200 m s À1 ) around the latitude 55°N, wind velocities of $150 m s À1 near the equator, and progressively weaker winds as more southern latitudes are probed. The haze distribution around Titan's limb at 250 km altitude is close to that predicted by the Global Circulation Model of Rannou et al. (2004) in the southern hemisphere, but a clearing north of 40°N is necessary to explain our data. This contrasts with Rannou et al.'s (2004) model, which predicts a very thick polar hood over Titan's northern polar regions. Simultaneous observations of the flashes at various wavelengths provide a dependence of t / l Àq , with q = 1.8 ± 0.5 between 0.51 and 2.2 mm for the tangential optical depth of the hazes at 250 km altitude.

We have carried out deep near-infrared imaging observations of the N159/ N160 star-forming region in the Large Magellanic Cloud. We observed an area of $380 arcmin 2 ($80,000 pc 2 at the distance of the LMC) in the J, H, and K s bands. The observations are deep enough to detect Herbig Ae/ Be stars down to $3 M in the LMC. We discovered a total of 338 and 464 candidate Herbig Ae/ Be and OB stars, respectively, based on the near-infrared colors and magnitudes. The Herbig Ae/ Be candidates comprise 10 clusters, the OB star candidates 13. We discovered an embedded Herbig Ae/ Be cluster in the N159 East giant molecular cloud (GMC) and a Herbig Ae/ Be cluster at the northeast tip of the N159 South GMC. Together with two neighboring H ii regions, the Herbig Ae/ Be cluster at the tip of the N159S GMC provides a hint of the beginning of sequential cluster formation in N159S. The spatial distributions of the Herbig Ae/ Be and OB clusters, in conjunction with previously known optical clusters and embedded massive stars, indicate (1) sequential cluster formation within each of the N159 and N160 star-forming regions and (2) large-scale sequential cluster formation over the entire observed region from N160 to N159S. Possible triggers for the large-scale cluster formation are the supergiant shell SGS 19 and an expanding superbubble. Some of the Herbig Ae/ Be clusters in the N159/ N160 complex are significantly larger in spatial extent than premain-sequence clusters of similar age in the Milky Way. Highly turbulent gas motion in the LMC is probably responsible for forming the large young clusters.