@article{ZhangLideGrijsetal.2015, author = {Zhang, Chaoli and Li, Chengyuan and de Grijs, Richard and Bekki, Kenji and Deng, Licai and Zaggia, Simone and Rubele, Stefano and Piatti, Andres E. and Cioni, Maria-Rosa L. and Emerson, Jim and For, Bi-Qing and Ripepi, Vincenzo and Marconi, Marcella and Ivanov, Valentin D. and Chen, Li}, title = {The vmc survey. XVIII. radial dependence of the Low-Mass, 0.55-0.82M(circle dot) stellar mass function in the galactic globular cluster 47 tucanae}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {815}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.1088/0004-637X/815/2/95}, pages = {9}, year = {2015}, language = {en} } @article{PiattideGrijsRubeleetal.2015, author = {Piatti, Andres E. and de Grijs, Richard and Rubele, Stefano and Cioni, Maria-Rosa L. and Ripepi, Vincenzo and Kerber, Leandro}, title = {The VMC survey - XV. The Small Magellanic Cloud-Bridge connection history as traced by their star cluster populations}, series = {Monthly notices of the Royal Astronomical Society}, volume = {450}, journal = {Monthly notices of the Royal Astronomical Society}, number = {1}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stv635}, pages = {552 -- 563}, year = {2015}, abstract = {We present results based on YJK(s) photometry of star clusters located in the outermost, eastern region of the Small Magellanic Cloud (SMC). We analysed a total of 51 catalogued clusters whose colour-magnitude diagrams (CMDs), having been cleaned from field-star contamination, were used to assess the clusters' reality and estimate ages of the genuine systems. Based on CMD analysis, 15 catalogued clusters were found to be possible non-genuine aggregates. We investigated the properties of 80 per cent of the catalogued clusters in this part of the SMC by enlarging our sample with previously obtained cluster ages, adopting a homogeneous scale for all. Their spatial distribution suggests that the oldest clusters, log(t yr(-1)) >= 9.6, are in general located at greater distances to the galaxy's centre than their younger counterparts - 9.0 <= log(t yr(-1)) <= 9.4 - while two excesses of clusters are seen at log(t yr(-1)) similar to 9.2 and log(t yr(-1)) similar to 9.7. We found a trail of younger clusters which follow the wing/bridge components. This long spatial sequence does not only harbour very young clusters, log(t yr(-1)) similar to 7.3, but it also hosts some of intermediate ages, log(t yr(-1)) similar to 9.1. The derived cluster and field-star formation frequencies as a function of age are different. The most surprising feature is an observed excess of clusters with ages of log(t yr(-1)) <9.0, which could have been induced by interactions with the LMC.}, language = {en} } @article{PiattideGrijsRipepietal.2015, author = {Piatti, Andres E. and de Grijs, Richard and Ripepi, Vincenzo and Ivanov, Valentin D. and Cioni, Maria-Rosa L. and Marconi, Marcella and Rubele, Stefano and Bekki, Kenji and For, Bi-Qing}, title = {The VMC survey - XVI. Spatial variation of the cluster formation activity in the innermost regions of the Large Magellanic Cloud}, series = {Monthly notices of the Royal Astronomical Society}, volume = {454}, journal = {Monthly notices of the Royal Astronomical Society}, number = {1}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stv2054}, pages = {839 -- 848}, year = {2015}, language = {en} } @article{MuravevaPalmerClementinietal.2015, author = {Muraveva, Tatiana and Palmer, Max and Clementini, Gisella and Luri, Xavier and Cioni, Maria-Rosa L. and Moretti, Maria Ida and Marconi, Marcella and Ripepi, Vincenzo and Rubele, Stefano}, title = {New near-infrared period-luminosity-metallicity relations for RR lyrae stars and the outlock for GAIA}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {807}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.1088/0004-637X/807/2/127}, pages = {17}, year = {2015}, abstract = {We present results of the analysis of 70 RR Lyrae stars located in the bar of the Large Magellanic Cloud (LMC). Combining the spectroscopically determined metallicity of these stars from the literature with precise periods from the OGLE III catalog and multi-epoch K-s photometry from the VISTA survey of the Magellanic Clouds system, we derive a new near-infrared period-luminosity-metallicity (PLKsZ) relation for RR Lyrae variables. In order to fit the relation we use a fitting method developed specifically for this study. The zero-point of the relation is estimated two different ways: by assuming the value of the distance to the LMC and by using Hubble Space Telescope parallaxes of five RR Lyrae stars in the Milky Way (MW). The difference in distance moduli derived by applying these two approaches is similar to 0.2 mag. To investigate this point further we derive the PL(Ks)Z relation based on 23 MW RR Lyrae stars that had been analyzed in Baade-Wesselink studies. We compared the derived PL(Ks)Z relations for RR Lyrae stars in the MW and LMC. Slopes and zero-points are different, but still consistent within the errors. The shallow slope of the metallicity term is confirmed by both LMC and MW variables. The astrometric space mission Gaia is expected to provide a huge contribution to the determination of the RR Lyrae PL(Ks)Z relation; however, calculating an absolute magnitude from the trigonometric parallax of each star and fitting a PL(Ks)Z relation directly to period and absolute magnitude leads to biased results. We present a tool to achieve an unbiased solution by modeling the data and inferring the slope and zero-point of the relation via statistical methods.}, language = {en} } @article{MartinNideverBeslaetal.2015, author = {Martin, Nicolas F. and Nidever, David L. and Besla, Gurtina and Olsen, Knut and Walker, Alistair R. and Vivas, A. Katherina and Gruendl, Robert A. and Kaleida, Catherine C. and Munoz, Ricardo R. and Blum, Robert D. and Saha, Abhijit and Conn, Blair C. and Bell, Eric F. and Chu, You-Hua and Cioni, Maria-Rosa L. and de Boer, Thomas J. L. and Gallart, Carme and Jin, Shoko and Kunder, Andrea and Majewski, Steven R. and Martinez-Delgado, David and Monachesi, Antonela and Monelli, Matteo and Monteagudo, Lara and Noel, Noelia E. D. and Olszewski, Edward W. and Stringfellow, Guy S. and van der Marel, Roeland P. and Zaritsky, Dennis}, title = {Hydra II: A faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters}, volume = {804}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {2041-8205}, doi = {10.1088/2041-8205/804/1/L5}, pages = {6}, year = {2015}, abstract = {We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact (r(h) = 68 +/- 11 pc) and faint (MV = -4.8 +/- 0.3), but well within the realm of dwarf galaxies. The stellar distribution of Hydra II in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 +/- 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.}, language = {en} }