ω Centauri is by far the most massive globular star cluster in the Milky Way, and possibly the remnant of a dwarf galaxy. As such, it contains a large number of variable stars of different classes. Here we report on an extensive, wide-field time-series study of ω Cen in the J and K S bands, which has allowed us to study the near-IR period-luminosity relations for different variability classes, including the first such relations for the SX Phoenicis stars.

An essential quantity required to understand the physics of the early Universe is the primordial scalar potential and its statistics. We present an inexpensive all-sky reconstruction of the potential from CMB temperature data as well as an extension including polarization data. Once explicitly having the potential, its statistics and underlying physics can be directly obtained avoiding expensive CMB analyses.

The K2 mission is a repurposed use of the Kepler spacecraft to perform high-precision photometry of selected fields in the ecliptic. We have developed an aperture photometry pipeline for K2 data which performs dynamic automated aperture mask selection, background estimation and subtraction, and positional decorrelation to minimize the effects of spacecraft pointing jitter. We also identify secondary targets in the K2 “postage stamps” and produce light curves for those targets as well. Pipeline results will be made available to the community. Here we describe our pipeline and the photometric precision we are capable of achieving with K2, and illustrate its utility with asteroseismic results from the serendipitous secondary targets.

The South African Astronomical Observatory (SAAO) observing station near Sutherland, Northern Cape in South Africa, is one of the darkest sites in the world for optical and IR astronomy. The SAAO hosts and operates several facilities, including the Southern African Large Telescope (SALT) and a number of international robotic telescopes. To ensure that the conditions remain optimal for astronomy, legislation called the Astronomy Geographic Advantage (AGA) Act, of 2007, was enacted. The Act empowers the Department of Science and Technology (DST) to regulate issues that pose a threat to optical and/or radio astronomy in areas declared Astronomy Advantage Areas in South Africa. For optical astronomy, the main challenges are those posed by light and dust pollution as result of wind energy developments, and petroleum gas and oil exploration/exploitation in the area. We give an update of possible threats to the quality of the night skies at SAAO, and the challenges relating to the AGA Act implementation and enforcement. We discuss measures that are put in place to protect the Observatory, including a study to quantify the threat by a planned wind energy facility.

We developed, based on the CoRoT experience, an automated tool called BART for Bayesian Analysis for the Ranking of Transit in order to perform a homogeneous and automated ranking of planetary candidates. We applied it to the candidates detected in the campaign 1 of K2.

Supermassive black hole binaries (SMBHBs) should be an inevitable consequence of the hierarchical growth of massive galaxies through mergers and the strongest sirens of gravitational waves (GWs) in the cosmos. Yet, their direct detection has remained elusive due to the compact (sub-parsec) orbital separations of gravitationally bound SMBHBs. Here we exploit a theoretically predicted signature of SMBHBs in the time domain. We have begun a systematic search for SMBHB candidates in the Pan-STARRS1 Medium Deep Survey (MDS) and reported our first significant detection of such a candidate from our pilot study of MD09 in Liu et al. (2015). Our candidate PSO J334.2028+01.4075 has a detected period of 542 days, varying persistently over the available baseline. From its archival spectrum, we estimated the black hole mass of the z = 2.06 quasar to be ∼1010 M⊙. The inferred ∼7 R s binary separation therefore puts this candidate in the regime of GW-dominated orbital decay, opening up the exciting possibility of finding GW sources detectable by pulsar timing arrays (PTAs) in a wide-field optical synoptic survey.

The preparation for The International Year of Astronomy 2009 stirred our interest in preparing star parties in Mexico. The lunar eclipse of February 20th 2008 was the perfect event for the first massive observation in Mexico City that attracted over 25,000 people. To accompany this event there were additional attractions: a massive astronomical lecture, more than 100 telescopes were set up for people to watch the sky, exhibits of astronomical images, children hands-on projects, rock concert, dance performance, and chats with astronomers. Already in 2009 a collective program was organized to involve more than 30 sites in Mexico to hold star parties at the same time once a year. These star parties were more in the spirit of science fairs, that include lectures, astronomy exhibits, children projects, as well as concerts and other cultural displays. The scope of each one of them depended on the local support from volunteers and from the local authorities. After the International Year of Astronomy the group that organized these star parties decided to continue its activities. The main attraction in these fairs has been the opportunity to see the Moon, Jupiter and Saturn (if observable) through a telescope. For this program the presence of the amateur astronomers has been crucial. They have brought their instruments to the sites and have generously taught the public how to look through the telescopes and pointed out to the interesting features on the sky.

Boulders are ubiquitous on the surfaces of asteroids and their spatial and size distributions provide information for the geological evolution and collisional history of parent bodies. We identify more than 200 boulders on near-Earth asteroid 4179 Toutatis based on images obtained by Chang'e-2 flyby. The cumulative boulder size frequency distribution (SFD) gives a power-index of −4.4 ± 0.1, which is clearly steeper than those of boulders on Itokawa and Eros, indicating much high degree of fragmentation. Correlation analyses with craters suggest that most boulders cannot solely be produced as products of cratering, but are probably survived fragments from the parent body of Toutatis, accreted after its breakup. Similar to Itokawa, Toutatis probably has a rubble-pile structure, but owns a different preservation state of boulders.

Interplanetary dust particles (IDPs) collected in the Earths stratosphere derive from collisions among asteroids and by the disruption and outgassing of short-period comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CP-IDPs have been linked to cometary parent bodies by their mineralogy, textures, C-content, and dynamical histories. CP-IDPs are fragile, fine-grained (< um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CP-IDPs, constituting 0.01-1% of the mass of the particles. The organic matter in CP-IDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10-100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including sub-um globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of sub-um isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild-2 samples returned by the Stardust mission. We will present an overview of the current state of understanding of the properties and origins of organic matter in primitive IDPs.

This review covers four current questions in the behavior of the atomic and molecular interstellar medium. These include whether the atomic gas originates primarily in cold streams or hot flows onto galaxies; what the filling factor of cold gas actually is in galactic regions observationally determined to be completely molecular; whether molecular hydrogen determines or merely traces star formation; and whether gravity or turbulence drives the dynamical motions observed in interstellar clouds, with implications on their star formation properties.

In a galaxy, chemical enrichment takes place in an inhomogeneous fashion, and the Galactic Halo is one of the places where the inhomogeneous effects are imprinted and can be constrained from observations. I show this using my chemodynamical simulations of Milky Way type galaxies. The scatter in the elemental abundances originate from radial migration, merging/accretion of satellite galaxies, local variation of star formation and chemical enrichment, and intrinsic variation of nucleosynthesis yields. In the simulated galaxies, there is no strong age-metallicity relation. This means that the most metal-poor stars are not always the oldest stars, and can be formed in chemically unevolved clouds at later times. The long-lifetime sources of chemical enrichment such as asymptotic giant branch stars or neutron star mergers can contribute at low metallicities. The intrinsic variation of yields are important in the early Universe or metal-poor systems such as in the Galactic halo. The carbon enhancement of extremely metal-poor (EMP) stars can be best explained by faint supernovae, the low [α/Fe] ratios in some EMP stars naturally arise from low-mass (~ 13 - 15M⊙) supernovae, and finally, the [α/Fe] knee in dwarf spheroidal galaxies can be produced by subclasses of Type Ia supernovae such as SN 2002cx-like objects and sub-Chandrasekhar mass explosions.

The framework of the present review is as follows. The Local Group (LG) is populated by dwarf galaxies belonging to different morphological types. Apparently these galaxies are very different. The questionsnaturally raised from this framework are many. Is there an evolutionary sequence among them? Do they share common progenitors? Is the environment at the origin of their differences? The methodwe propose to answer to these questions is by investigating the chemical evolution of dwarf galaxies and their mass-metallicity relation (MZR). To this aim we use metallicities derived from planetary nebulae, since this stellar population is present in the star-forming (dwarf irregular, dIrr) as well as in the quiescent (dwarf spheroidal, dSph) galaxies. The results, actually, show that both dIrr and dSph galaxies of the LG follow the same MZR, at variance with the differences claimed in the past. These results are in good agreement with the recently derived MZR, based on stellar instead of the nebular metallicities of the LG dwarf galaxies. Moreover, our MZR is also consistent with the global MZR of SLOAN star-forming galaxies, which spans a wider stellar mass range (~ 106 - 1011 M⊙) than the LG dwarfs.

For even small astronomy projects, the petabyte scale is now upon us. The Asteroid Terrestrial-impact Last Alert System (Tonry 2011) will survey the entire visible sky from Hawaii multiple times per night to search for near-Earth asteroids on impact trajectories. While the ATLAS optical system is modest by modern astronomical standards — two 0.5 m F/2.0 telescopes — each night the ATLAS system will measure nearly 109 astronomical sources to a photometric accuracy of <5%, totaling 1012 individual observations over its initial 3-year mission. This ever-growing dataset must be searched in real-time for moving objects and transients then archived for further analysis, and alerts for newly discovered near-Earth asteroids (NEAs) disseminated within tens of minutes from detection. ATLAS's all-sky coverage ensures it will discover many ‘rifle shot’ near-misses moving rapidly on the sky as they shoot past the Earth, so the system will need software to automatically detect highly-trailed sources and discriminate them from the thousands of low-Earth orbit (LEO) and geosynchronous orbit (GEO) satellites ATLAS will see each night. Additional interrogation will identify interesting phenomena from millions of transient sources per night beyond the solar system. The data processing and storage requirements for ATLAS demand a ‘big data’ approach typical of commercial internet enterprises. We describe our experience in deploying a nimble, scalable and reliable data processing infrastructure, and suggest ATLAS as steppingstone to data processing capability needed as we enter the era of LSST.

We present an overview of our Galactic Archaeology (GA) survey program with the Prime Focus Spectrograph (PFS) for Subaru. Following successful design reviews, the instrument is now under construction with first light anticipated in 2018. Main characteristics of PFS and the science goals in our PFS/GA program are described.

In order to understand the star formation process under the influence of H ii regions, we have carried out extensive investigations to well selected star-forming regions which all have been profoundly affected by existing massive O type stars. On the basis of multi-wavelength data from mid-infrared to millimeter collected using Spitzer, Herschel, and ground based radio telescopes, the physical status of interstellar medium and star formation in these regions have been revealed. In a relatively large infrared dust bubble, active star formation is undergoing and the shell is still expanding. Signs of compressed gas and triggered star formation have been tentatively detected in a relatively small bubble. The dense cores in the Rosette Molecular Complex detected at 1.1 mm using SMA have been speculated to have a likely triggered origin according to their spatial distribution. Although some observational results have been obtained, more efforts are necessary to reach trustworthy conclusions.

The VAMDC Consortium is a worldwide consortium which federates Atomic and Molecular databases through an e-science infrastructure and a political organisation. About 90% of the inter-connected databases handle data that are used for the interpretation of spectra and for the modeling of media of many fields of astrophysics. This paper presents how the VAMDC Consortium is organised in order to publish atomic and molecular data for astrophysics.

We use the UCAC4 and SDSS proper motions of about 7500 RR Lyrae type variables located within ~10 kpc from the Sun to study the dependence of their velocity ellipsoid on Galactocentric distance in the RG = 3–17 kpc interval. The radial velocity dispersion, σVR, decreases from ~190 km/s at RG = 3.5–5.5 kpc down to ~100 km/s at RG = 13–15 kpc, and the σVT/σVR ratio remains virtually constant (σVT/σVR ~0.54–0.64) in the Galactocentric distance interval from RG = 4.5 kpc to RG = 10.5 kpc increasing to ~0.9 both toward the Galactic center and beyond RG = 11 kpc.

There is an ongoing argument regarding galaxies, like there is regarding children, of whether the final outcome is driven primarily by nature or nurture. In the case of galaxies, the total mass plays the role of genetics (nature) and the number of nearby galaxies plays the role of family life (nurture). Untangling the role of each has been particularly difficult for galaxies because the mass of a galaxy is closely tied to its environment.

The point sources in the Bright Source Catalogue (BSC) of the AKARI Far–Infrared Surveyor (FIS) were classified based on their far–IR and mid–IR fluxes and colours using Quadratic Discriminant Analysis method (QDA) and Support Vector Machines (SVM). The reliability of our results show that we can successfully separate galactic and extragalactic AKARI point sources in the multidimensional space of fluxes and colours. However, differentiating among the extragalactic sub–types needs further information.

The Bak Tang Weisenfeld (BTW) sandpile process is a model of a complex dynamical system with a large collection of particles or grains in a node that sheds load to their neighbours when they reach capacity. The cascades move around the system till it reaches stability with a critical point as an attractor. The BTW growth process shows self-organized criticality (SOC) with power- law distribution in cascade sizes having slope -5/3. This self-similarity of structure is synonymous with the fractal structure found in molecular clouds of Kolmogorov dimension 1.67 and by treating cascades as waves, scaling functions are found to be analogous to those observed for velocity structure functions in fluid turbulence. In this paper, we show that this is a naturally occuring universal process giving rise to scale - free structures with size limited only by the number of infalling grains. We also compare the BTW process with other sandpile models such as the Manna and Zhang processes. We find that the BTW sandpile model can be applied to a wide range of objects including molecular clouds, accretion disks and perhaps galaxies.