New RR Lyrae variables in binary systems

Despite their importance, very few RR Lyrae (RRL) stars have been known to reside in binary systems. We report on a search for binary RRL in the OGLE-III Galactic bulge data. Our approach consists in the search for evidence of the light-travel time effect in so-called observed minus calculated ($O-C$) diagrams. Analysis of 1952 well-observed fundamental-mode RRL in the OGLE-III data revealed an initial sample of 29 candidates. We used the recently released OGLE-IV data to extend the baselines up to 17 years, leading to a final sample of 12 firm binary candidates. We provide $O-C$ diagrams and binary parameters for this final sample, and also discuss the properties of 8 additional candidate binaries whose parameters cannot be firmly determined at present. We also estimate that $\gtrsim 4$ per cent of the RRL reside in binary systems.Comment: MNRAS Letters, in pres

The VVV Survey reveals classical Cepheids tracing a young and thin stellar disk across the Galaxy's bulge

Solid insight into the physics of the inner Milky Way is key to understanding our Galaxy's evolution, but extreme dust obscuration has historically hindered efforts to map the area along the Galactic mid-plane. New comprehensive near-infrared time-series photometry from the VVV Survey has revealed 35 classical Cepheids, tracing a previously unobserved component of the inner Galaxy, namely a ubiquitous inner thin disk of young stars along the Galactic mid-plane, traversing across the bulge. The discovered period (age) spread of these classical Cepheids implies a continuous supply of newly formed stars in the central region of the Galaxy over the last 100 million years.Comment: Accepted for publication in The Astrophysical Journal Letters. Near-IR finding charts of the Cepheids are available at the following URL: http://www.astro.puc.cl/~idekany/pub/inner_disk_ceph_fc.pn

On the modulation of RR Lyrae stars in the globular cluster M3

A new, extended time-series photometry of M3 RR Lyrae stars has revealed that four of the ten double-mode stars show large-amplitude Blazhko modulation of both radial modes. The first, detailed analysis of the peculiar behavior of the unique, Blazhko RRd stars is given. While the P1/P0 period ratio is normal, and the overtone mode is dominant in the other RRd stars of the cluster, the period ratio is anomalous and the fundamental mode has a larger (or similar) mean amplitude than the overtone has in Blazhko RRd stars. The modulations of the fundamental and overtone modes are synchronized only in one of the Blazhko RRd stars. No evidence of any connection between the modulations of the modes in the other three stars is found. The Blazhko modulation accounts, at least partly, for the previously reported amplitude and period changes of these stars. Contrary to the $\sim50$$$ Blazhko statistics of RRab and RRd stars, Blazhko modulation occurs only in 10$$ of the overtone variables in M3. Four of the five Blazhko RRc stars are bright, evolved objects, and one has a similar period and brightness as Blazhko RRd stars have. The regions of the instability strip with high and low occurrence rate of the Blazhko modulation overlap with the regions populated by first- and second-generation stars according to theoretical and observational studies, raising up the possibility that the Blazhko modulation occurs preferentially in first-generation RR Lyrae stars.Comment: 6 pages, 4 figures, accepted for publication in ApJ

The aromatic nature of residue 66 of the 11-kDa subunit of ubiquinol-cytochrome <i>c</i> oxidoreductase of the yeast <i>Saccharomyces cerevisiae</i> is important for the assembly of a functional enzyme

AbstractTransformation of multi- and single-copy plasmids carrying a mutated version (LTN2, region 66-YWYWW-70 replaced by SASAA) of QCR8, the gene encoding the 11-kDa subunit of ubiquinol-cytochrome c oxidoreductase of Saccharomyces cerevisiae, to a QCR80 strain indicated the importance of this aromatic region for the assembly of a functional enzyme. Sequencing of plasmids giving spontaneous restoration of growth to some colonies among the single-copy LTN2 transformants showed that changing the sequence SASAA into the sequence FASAA could, to a large extent, overcome the observed assembly defect, indicating the importance of the aromatic nature of residue 66

Japanese investment on the Gold Coast : the interface of globalization and locality

This study explored the interface between the forces of globalization and a given place, at a given time, the Gold Coast during the 1980s. The global economic boom of the 1980s was one in which the role of Japan was particularly important. In less than half a decade capital flows from Japan surged to make it the world\u27s largest investor. Locations in the Pacific Basin were favoured destinations for Japanese investment, one of the most significant was the Gold Coast. Japanese capital and tourism helped transform its urban area from a national resort to an international tourist destination and resort centre, The surge of capital arriving to the Gold Coast was a function of economic conditions in Japan, as was its steep reduction after November 1989, Thus the Gold Coast became integrated into global capital flows and so dependent on decisions made in Tokyo, one of the main financial centres of the world. However this study has also sought to explore a more complex reality; namely, that this place also became the interface of complex cultural forces and perceptions. The wealth of the Japanese investors on the Gold Coast enabled them to realize their dream of developing projects in the most fashionable global styles. These styles were essentially Western, and it was onto these that their Japanese owners ascribed their own meanings; meanings that reflected the cultural baggage that they had brought from Japan, and through which were filtered the economic and environmental realities of the Gold Coast. The Gold Coast as locality also included residents. Hence it became an interface between two different groups of people, the Japanese and the strongly Anglo-Celtic local community. Some in the local community perceived the Japanese presence as a threat to their perception of the Gold Coast, in fact, a threat to their perception of Australia\u27s national identity. A campaign based on the politics of memory of the Japanese developed on the Gold Coast. Within weeks it became a national debate in which isolationalist, if not xenophobic traditionalists, concentrated on the Gold Coast challenged the economic rationalism and multicultural tolerance of the self-interested and ideologically convinced advocates of globalization. Governments at all levels sought to arbitrate, to legitimize standpoints, but more often than not were seen to move into positions of ineffectual flexibility. The forces of globalization on the Gold Coast were catalysts for change that in turn provoked local opposition which rapidly became a debate about national identity and direction. It is in the exploration of the complex and contradictory economic, cultural and political forces engendered by globalization that this study has sought to make a distinctive contribution

Eclipse timing variation analysis of OGLE-IV eclipsing binaries towards the Galactic Bulge – I. Hierarchical triple system candidates

We report a study of the eclipse timing variation (ETV) of short period ($P_1\le 6^d$) eclipsing binaries (EB) monitored during the photometric survey OGLE-IV. From the 425\,193 EBs we selected approximately 80\,000 binaries that we found suitable for further examination. Among them we identified 992 potential hierarchical triple (or multiple ) system candidates exhibiting light-travel-time effect (LTTE). Besides, we obtained the orbital parameters of these systems and carried out statistical analyses on the properties of these candidates. We found that (i) there is a significant lack of triple systems where the outer period is less than 500 days; (ii) the distribution of the outer eccentricities has a maximum around $e_2\approx0.3$; (iii) the outer mass ratio calculated from an estimated minimum mass of the third component is lower than $q_2\sim 0.5$ for the majority of the sample. We also present some systems that deserve special attention. (i) There are four candidates that show double periodic ETV, which we explain by the presence of a fourth companion. (ii) For two systems the perturbations of the third component are also found to be significant therefore we give a combined dynamical and LTTE ETV solution. (iii) For one system the third component is found to be probably in the substellar mass domain.Comment: Accepted for publication in MNRA