The origin of Galactic halo stars and the contribution of globular clusters (GC) to this stellar population have long been (and still are) debated. The discovery of multiple stellar populations with peculiar chemical properties in GCs both in the Milky Way and in Local Group galaxies recently brought a renewal on these questions. Indeed most of the scenarios that compete to reproduce the present-day GC characteristics call for fast expulsion of both gas and low-mass stars from these clusters in their early infancy. In this framework, the initial masses of GCs could have been 8 to 25 times higher than their present-day stellar mass, and they could have contributed to 5 to 20 % of the low-mass stars in the Galactic halo. Here we revisit these conclusions, which are in tension with observations of dwarf galaxies and of young massive star clusters in the Local Group. We come back in particular on the paradigm of gas expulsion from massive star clusters, and propose an alternative interpretation of the GC abundance properties. We conclude by proposing a major revision of the current concepts regarding the role massive star clusters play in the assembly of galactic haloes.

We use ultra-deep imaging from the IAC Stripe 82 Legacy Project to study the surface photometry of 22 nearby, face-on to moderately inclined spiral galaxies. The reprocessed and co-added SDSS/Stripe 82 imaging allows us to probe down to 29–30 r′-mag/arcsec2 and thus reach into the very faint outskirts of the galaxies. We find extended stellar haloes in over half of our sample galaxies, and truncations in three of them. The presence of stellar haloes and truncations is mutually exclusive, and we argue that the presence of a stellar halo can hide a truncation. We find that the onset of the halo and the truncation scales tightly with galaxy size. We highlight the importance of a proper analysis of the extended wings of the point spread function (PSF), finding that around half the light at the faintest levels is from the inner regions of a galaxy, though not the nucleus, re-distributed to the outskirts by the PSF. We discuss implications of this effect for future deep imaging surveys, such as with the LSST.

Recent surveys at infrared and submillimeter wavelengths with the Spitzer and Herschel space observatories suggest that star formation in dense molecular gas is governed by essentially the same “laws” in nearby Galactic clouds and distant external galaxies. This raises the possibility of a unified picture for star formation in the Universe from individual-cloud scales to galaxy–wide scales. We summarize the star formation scenario favored by Herschel studies of the nearest molecular clouds of the Galaxy which point to the key role of the quasi-universal filamentary structure pervading the cold interstellar medium.

High-resolution imaging reveals clumpy morphologies among z = 1 – 3 galaxies. Most of these galaxies are dominated by disk rotation, which led to conclude that the observed clumps are generated from disk fragmentation due to gravitational instability. Despite the kpc-scale resolution attained by the most advanced facilities and numerical simulations, these clumps are barely resolved at z > 1. Thanks to the stretching and magnification power provided by gravitational lensing, we reach the sub-kpc resolving power to unveil their physics. From our literature compilation of data, we show that without lensing there is a bias toward clumps with high masses and sizes. The high-redshift clumps identified in lensed galaxies have stellar masses 2 orders of magnitude lower and a median size of 250 pc. They resemble local star clusters observed in the most intensively star-forming galaxies. The clump masses and sizes observed in lensed galaxies agree with new simulations, which show that the Toomre instability criterion overestimates the clump masses by a factor of 5 – 6.

We look at applications of recent work in theoretical and experimental spectroscopy for the analysis of IR data concerning giant planets, Titan and possibly exoplanets.

Using the Yunnan-II evolutionary population synthesis models comprising binary stars, we find that the inclusion of binary stars can raise the derived stellar metallicity Z* and/or age t (degeneracy problem), raise the stellar mass M*, lower the gaseous metallicity Z gas and star formation rate (SFR) of galaxies. This means that a few stars form recently in galaxies, while more stars form during the entire evolution process when considering binary stars. If the degeneracy between t and Z* can be broken, its effect on the feedback process and star formation history can be determined.

Since the first detection of intracluster planetary nebulae in 1996, imaging and spectroscopic surveys identified such stars to trace the radial extent and the kinematics of diffuse light in clusters. This topic of research is tightly linked with the studies of galaxy formation and evolution in dense environment, as the spatial distribution and kinematics of planetary nebulae in the outermost regions of galaxies and in the cluster cores is relevant for setting constraints on cosmological simulations. In this sense, extragalactic planetary nebulae play a very important role in the near-field cosmology, in order to measure the integrated mass as function of radius and the orbital distribution of stars in structures placed in the densest regions of the nearby universe.

Kepler observations show that starspots and superflares are present in A stars. An analysis of Kepler short-cadence data shows that the relative number of A/F flare stars is only a factor of four smaller than K/M flare stars, which can be explained as a selection effect. The average maximum flare amplitude does not depend much on spectral type, which is to be expected if the size of the active region scales in proportion to the stellar radius. The presence of starspots and superflares in A stars suggests that these stars have magnetic fields. However, X-ray observations show that A stars do not possess coronae. I therefore conclude that convection in the stellar envelope is a necessary condition for the formation of the corona. A magnetic field may be necessary to enable coronal heating.

A giant molecular cloud has been detected surrounding the supernebula in NGC 5253, revealing details of the formation and feedback process in a very massive star cluster. “Cloud D” was recently mapped in CO J = 3–2 with the Submillimeter Array. The cloud surrounds a currently forming massive cluster of mass ~ 106 M⊙, and luminosity ~ 109 L⊙. Cloud D is hot, clearly associated with the cluster, yet kinematically relatively quiescent. The dust mass is ~ 15,000 M⊙, for a gas-to-dust ratio of ~ 50, nearly an order of magnitude lower than expected for this low metallicity galaxy. We posit that enrichment by the cluster, leading to a stalled cluster wind, has created the unusual conditions in Cloud D. The absence of current mechanical impact of the young cluster on the cloud, in spite of the presence of thousands of O stars, may permit future generations of stars to form near the massive cluster.

The Infrared Camera (IRC) onboard AKARI has a near-infrared (2--5μm) spectroscopic capability with high sensitivity that allows us to study the major ice components in various objects. In particular, H2O and CO2 ice absorption features have been detected towards nearby galaxies, including several young stellar objects (YSOs) in the Large Magellanic Cloud (LMC), as well as a number of HII region-PDR complexes for the first time by IRC spectroscopy. While observations in the LMC show a high ratio (~0.34) of the CO2 to H2O ice column densities, the ratios in Galactic HII-region-PDR complexes are in the range of 0.1--0.2, being compatible with those found in Galactic massive YSOs in previous studies. The good correlation supports concurrent formation of the two ice species on the grain surface and the higher ratio in the low-metallicity LMC suggests possible environmental effects in the formation process.

During a supernova explosion, fluid instabilities are generated because the star is in a hydrodynamically unstable situation, which is like the effects of stirring a fire or blowing air into a hot grill. The resulting mixing of the supernova ejecta may be observable. Here, we briefly discuss the multidimensional simulations of supernovae from very massive stars.

Comet composition and properties provide information on chemical and physical processes that occurred in the early Solar system, 4.6 Gyr ago. The study of comets and of star-forming regions both help for a better understanding of the formation of planetary systems. A review of our present knowledge of cometary composition is presented. We also discuss laboratory studies that would be helpful for data analysis.

Herschel revealed high-density cloud filaments of several pc3, which are forming clusters of OB-type stars. Counting Herschel protostars gives a direct measure of the mass of stars forming in a period of ~105 yrs, the “instantaneous” star formation activity. Given their activity, these so-called mini-starburst cloud ridges could be seen as “miniature and instant models” of starburst galaxies. Their characteristics could shed light on the origin of massive clusters.

During late October 2014, active region NOAA 2192 caused an unusual high level of solar activity, within an otherwise weak solar cycle. While crossing the solar disk, during a period of 11 days, it was the source of 114 flares of GOES class C1.0 and larger, including 29 M- and 6 X-flares. Surprisingly, none of the major flares (GOES class M5.0 and larger) was accompanied by a coronal mass ejection, contrary to statistical tendencies found in the past. From modeling the coronal magnetic field of NOAA 2192 and its surrounding, we suspect that the cause of the confined character of the flares is the strong surrounding and overlying large-scale magnetic field. Furthermore, we find evidence for multiple magnetic reconnection processes within a single flare, during which electrons were accelerated to unusual high energies.

We carried out a systematic study of the electronic structure of doubly-ionized Fe-peak species, from Sc III to Ni III. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities were computed using the pseudo-relativistic Hartree-Fock (HFR) method and the central Thomas-Fermi-Dirac-Amaldi potential approximation implemented in the AUTOSTRUCTURE code. This multi-platform approach allowed for consistency checks and intercomparison and has proven very useful in many previous works for estimating the uncertainties affecting the radiative data.

The role of the large-scale structure is one of the most important theme in studying galaxy formation and evolution. However, it has been still mystery especially at z>2. On the basis of our ALMA 1.1 mm observations in a z ~ 3 protocluster field, it is suggested that submillimeter galaxies (SMGs) preferentially reside in the densest environment at z ~ 3. Furthermore we find a rich cluster of AGN-host SMGs at the core of the protocluster, combining with Chandra X-ray data. Our results indicate the vigorous star-formation and accelerated super massive black hole (SMBH) growth in the node of the cosmic web.

We report a multi-wavelength study of a recent major flare (~ 80,000 Jy at VLSR ~ -98.1 km s−1) of the 22-GHz water maser in W49A. In February 2014, we started monthly monitoring with the Effelsberg 100-m radio telescope. In May 2014, we carried out the nearly simultaneous observations of the 22-GHz transition with selected submillimeter water transitions using the IRAM 30-m telescope (at 183 GHz) and the Atacama Pathfinder Experiment (APEX) 12-m telescope (from 321 to 475 GHz). We have also performed interferometric observations using the NRAO Very Long Baseline Array (VLBA) at 22 GHz and the Submillimeter Array (SMA) at 321 and 325 GHz. One remarkable result is the detection of very high velocity emission features in several transitions. Our data also represent its first detection of the 475-GHz water transition in a star-forming region. Studying these multiple masing transitions in conjunction with theoretical modeling of their excitation not only places strong constraints on the physical conditions of the masing gas but also allows us to study their association with the embedded massive stellar cluster in W49A.

After years of thinking the Moon is dry, we now know there are three manifestations in which water appears on the Moon today: 1) Previously hypothesized buried deposits of volatiles at the lunar poles were found at Cabeus crater. There are questions about the origin of such volatiles (i.e., in-falling comets & meteorites, migration of recently formed surficial OH/H2O, and accumulated release from the interior), but there is no doubt the water is there. 2) Widespread, thinly-distributed, surficial OH (or H2O) has been clearly detected across all types of lunar terrain. The consensus is that the OH is derived from solar wind, but we do not know how quickly it forms, nor how mobile it is. 3) The amount of water present soon after the Moon formed is now documented in new analyses of lunar materials in volcanic glass beads, apatites and plagioclase feldspars. Apollo era sample analyses were not precise enough to distinguish between indigenous lunar water and terrestrial contamination. Measurements with modern equipment are more precise (both elemental and isotopic), and can better constrain a host of processes (e.g. diffusion, thermal cycling). Scientists around the world are studying lunar water. Ongoing analyses are informing a number of hypotheses and theories about the connection between the Earth and its wet Moon.

Neutron star mergers are one of the candidate astrophysical site(s) of r-process. Several chemical evolution studies however pointed out that the observed abundance of r-process is difficult to reproduce by neutron star mergers. In this study, we aim to clarify the enrichment of r-process elements in the Local Group dwarf galaxies. We carry out numerical simulations of galactic chemo-dynamical evolution using an N-body/smoothed particle hydrodynamics code, ASURA. We construct a chemo-dynamical evolution model for dwarf galaxies assuming that neutron star mergers are the major source of r-process elements. Our models reproduce the observed dispersion in [Eu/Fe] as a function of [Fe/H] with neutron star mergers with a merger time of 100 Myr. We find that star formation efficiency and metal mixing processes during the first ≲ 300 Myr of galaxy evolution are important to reproduce the observations. This study supports that neutron star mergers are a major site of r-process.

Boulders, rocks and regolith on fast rotating asteroids (<2.5 hours) are modeled to slide towards the equator due to a strong centrifugal force and a low cohesion force. As a result, regions of fresh subsurface material can be exposed. Therefore, we searched for color variation on small and fast rotating asteroids. We describe a novel technique in which the asteroid is simultaneously observed in the visible and near-IR wavelength range. In this technique, brightness changes due to atmospheric extinction effects can be calibrated across the visible and near-IR images. We use V- and J-band filters since the distinction in color between weathered and unweathered surfaces on ordinary chondrite-like bodies is most prominent at these wavelengths and can reach ~25%. To test our method, we observed 3 asteroids with Cerro Tololo's 1.3 m telescope. We find ~5% variation of the mean V-J color, but do not find any clearly repeating color signature through multiple rotations. This suggests that no landslides occurred within the timescale of space weathering, or that Landslides occurred but the exposed patches are too small for the measurements' uncertainty.