Probing the Local Bubble with Diffuse Interstellar Bands. III. The Northern hemisphere data and catalog

We present a new high signal-to-noise (S/N) observations of the Diffuse Interstellar Bands (DIBs) in the Local Bubble and its surroundings. We observed 432 sightlines and obtain the equivalent widths of $lambda$5780 and $lambda$5797 AA DIBs up to distance of $sim$ 200 pc. All observations have been carried out by using Intermediate Dispersion Spectrograph (IDS) on 2.5 m Isaac Newton Telescope, during three years, to reach a minimum S/N ratio of $sim$ 2000. All $lambda$5780 and $lambda$5797 absorptions are presented in this paper and the observed values of interstellar parameter; $lambda$5780, $lambda$5797, Na I D lines including the uncertainties are tabulated.

The UK Infrared Telescope M33 monitoring project. IV. Variable red giant stars across the galactic disc

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this fourth paper of the series, we present a search for variable red giant stars in an almost square degree region comprising most of the galaxys disc, carried out with the WFCAM instrument in the K band. These data, taken during the period 2005--2007, were complemented by J- and H-band images. Photometry was obtained for 403 734 stars in this region; of these, 4643 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. The variable stars are concentrated towards the centre of M33, more so than low-mass, less-evolved red giants. Our data were matched to optical catalogues of variable stars and carbon stars and to mid-infrared photometry from the Spitzer Space Telescope. Most dusty AGB stars had not been previously identified in optical variability surveys, and our survey is also more complete for these types of stars than the Spitzer survey. The photometric catalogue is made publicly available at the Centre de Donnees astronomiques de Strasbourg.

Probing the Local Bubble with Diffuse Interstellar Bands. II. The DIB properties in the Northern hemisphere

We present a new high signal to noise ratio spectroscopic survey of the Northern hemisphere to probe the Local Bubble and its surroundings using the $lambda 5780$ AA and $lambda 5797$ AA Diffuse Interstellar Bands (DIBs). We observed 432 sightlines to a distance of 200 pc over a duration of 3 years. In this study, we establish the $lambda 5780$ and $lambda 5797$ correlations with Na I, Ca II and E(B-V), for both inside and outside the Local Bubble. The correlations show that among all neutral and ionized atoms, the correlation between Ca II and $lambda5780$ is stronger than its correlation with $lambda5797$, suggesting that $lambda5780$ is more associated with regions where Ca$^{+}$ is more abundant. We study the $lambda5780$ correlation with $lambda5797$, which shows a tight correlation within and outside the Local Bubble. In addition we investigate the DIB properties in UV irradiated and UV shielded regions. We find that, within and beyond the Local Bubble, $lambda5797$ is located in denser parts of clouds, protected from UV irradiation, while $lambda5780$ is located in the low density regions of clouds.

The star formation history of the Magellanic Clouds derived from long-period variable star counts

We present the first reconstruction of the star formation history (SFH) of the Large and Small Magellanic Clouds (LMC and SMC) using Long Period Variable stars. These cool evolved stars reach their peak luminosity in the near-infrared; thus, their K-band magnitudes can be used to derive their birth mass and age, and hence the SFH can be obtained. In the LMC, we found a 10-Gyr old single star formation epoch at a rate of $sim1.5$ M$_odot$ yr$^{-1}$, followed by a relatively continuous SFR of $sim0.2$ M$_odot$ yr$^{-1}$, globally. In the core of the LMC (LMC bar), a secondary, distinct episode is seen, starting 3 Gyr ago and lasting until $sim0.5$ Gyr ago. In the SMC, two formation epochs are seen, one $sim6$ Gyr ago at a rate of $sim0.28$ M$_odot$ yr$^{-1}$ and another only $sim0.7$ Gyr ago at a rate of $sim0.3$ M$_odot$ yr$^{-1}$. The latter is also discernible in the LMC and may thus be linked to the interaction between the Magellanic Clouds and/or Milky Way, while the formation of the LMC bar may have been an unrelated event. Star formation activity is concentrated in the central parts of the Magellanic Clouds now, and possibly has always been if stellar migration due to dynamical relaxation has been effective. The different initial formation epochs suggest that the LMC and SMC did not form as a pair, but at least the SMC formed in isolation.