Nearby galaxies come in two flavors: red quiescent galaxies (QGs) with old stellar populations, and blue young star-forming galaxies (SFGs). This color bimodality seems to be already in place at z = 2 − 3, presenting also strong correlations with size and morphology. Surprisingly, massive QGs at higher redshifts are ~5 times smaller than local, equal mass analogs. In contrast, most of the massive SFGs at these redshifts are still relatively large disks. The strong bimodality in both SFR and sizes indicates that some SFGs must experience strong structural transformations accompanied by a rapid truncation of the star-formation to match the observed properties of QGs. Using high-resolution HST/WFC3 F160W imaging from the CANDELS survey in GOODS-S and UDS, along with multi-wavelength ancillary data, we analyze stellar masses, SFRs and sizes of a sample of massive (M* > 1010M⊙) galaxies at z = 1.4 − 3.0 to identify a population of compact SFGs with similar structural properties as compact QGs at z~2. We also find that the number density of QGs increases rapidly since z = 3. Among these, the number of compact QGs builds up first, and only at z < 1.8 we do start finding a sizable number of extended QGs. This suggests that the bulk of these galaxies are assembled at late times by both continuous migration (quenching) of non-compact SFGs and size growth of cQGs. As a result of this growth, the population of cQGs disappears by z~1. Simultaneously, we identify a population of compact SFGs (cSFGs) whose number density decreases steadily with time since z = 3.0, being almost completely absent at z < 1.4. The number of cSFGs makes up less than 20% of all massive SFGs, but they present similar number densities as cQGs down to z~2, suggesting an evolutionary link between the two populations.

We test two contemporary low-mass atmospheric models using three L dwarfs with distances and published spectra. We find that the two models do not predict the same trends for temperature, gravity and metallicity in absorption lines. We find that one model appears to better reflect the temperature, but this sample is too small to investigate the other parameters in depth.

We present quadrupole moments of rotating neutron and strange stars calculated using standard Hartle Thorne approach. We demonstrate differences between neutron and strange star parameters connected with quadrupole moments and how this parameters could be, in the case of neutron stars, approximated almost independently on neutron star equation of state.

This is an overview of nuclear star cluster observations, covering their structure, stellar populations, kinematics and possible connection to black holes at the centers of galaxies.

The interstellar medium (ISM) plays an important role in the formation and evolution of a galaxy. The ISM provides the material to form stars and stars in turn inject radiation, metals, and mechanical energy into the ISM, altering the physical conditions, abundances, and distribution of the ISM and affecting future generations of star formation. It is thus essential that we understand the physical structure of the ISM, the physical processes that operate in the ISM, and the interplay between stars and ISM.

We investigate the dust velocity and spatial distribution in an eccentric protoplanetary disk under the secular gravitational perturbation of an embedded planet of about 5 Jupiter masses. We first employ the FARGO code to obtain the two-dimensional density and velocity profiles of the gas disk with the embedded planet in the quasi-steady state. We then apply the secular perturbation theory and incorporate the gas drag to estimate the dust velocity on the secular timescale. The dust-to-gas ratio of the unperturbed disk is simply assumed to be 0.01. In our fiducial disk model with the planet at 5 AU, we find that for 0.01 cm– to 1 m–sized dust particles well coupled to the gas, the dust behaves similarly to the gas and exhibits non-axisymmetric dynamics as a result of eccentric orbits. However, for the case of a low-density gaseous disk (termed “transition disk” henceforth in this article) harboring the planet at 100 AU, the azimuthal distributions of dust of various sizes can deviate significantly.

Observations of the Cosmic Microwave Background (CMB) have played a leading role in establishing an understanding of the structure and evolution of the Universe on the largest scales. This achievement has been enabled by a series of extremely successful experiments, coupled with the simplicity of the relationship between the cosmological theory and data. Antarctic experiments, including both balloon-borne telescopes and instruments at the South Pole, have played a key role in realizing the scientific potential of the CMB, from the characterization of the temperature anisotropies to the detection and study of the polarized component. Current and planned Antarctic long duration balloon experiments will extend this heritage of discovery to test theories of cosmic genesis through sensitive polarized surveys of the millimeter-wavelength sky. In this paper we will review the pivotal role that Antarctic balloon borne experiments have played in transforming our understanding of the Universe, and describe the scientific goals and technical approach of current and future missions.

We investigate the relations between tachocline-based dynamos and the surface flux transport mechanisms in stars with outer convection zones. Using our combined models of flux generation and transport, we demonstrate the importance of the buoyant rise of magnetic flux, which physically determines the emergence latitudes and tilt angles of bipolar magnetic regions. The combined effects of the dynamo strength, flux rise, and surface transport lead to various cyclic and non-cyclic time series of total unsigned surface magnetic flux.

We propose to determine the mass of isolated neutron stars through gravitational microlensing. We show that the all-sky microlensing pulsar event rate is ~2.8 × 10−10 per year per background source (/yr/source). Microlensing neutron star event rate would contribute ~20% to the total Galactic event rate at time-scale of ~15 days. We also present catalogue comparisons between known pulsars and background stars. We find that several pulsars would pass by background stars closely and may cause observable astrometric microlensing phenomenon. According to our covariance analysis, the uncertainty of masses determined through astrometric microlensing could be ~20%. Therefore, gravitational microlensing is a promising way to determine the mass of isolated neutron stars with future advanced radio and optical telescopes.

The optical variability of a sample of 44 FSRQs and 18 SSRQs in the SDSS stripe 82 region is investigated by using the multi-epoch data covering nine years. The variabilities are clearly detected in each source with the amplitude in r band, from 0.18 to 3.46 mag. Twenty-five of 44 FSRQs show a bluer-when-brighter trend (BWB), while only one FSRQ shows a redder-when-brighter trend, which is in contrast to our previous results. Eight of 18 SSRQs display a BWB. We found an anti-correlation between the Eddington ratio and the variability amplitude in r band for SSRQs, which is similar to that in radio-quiet AGNs. This implies that the thermal emission from the accretion disk may be responsible for the variability in SSRQs.

NEOs come close to the Earth's orbit so that any dust ejected from them, might be seen as a meteor shower. Orbits evolve rapidly, so that a similarity of orbits at one given time is not sufficient to prove a relationship, orbital evolution over a long time interval also has to be similar. Sporadic meteoroids can not be associated with a single parent body, they can only be classified as cometary or asteroidal. However, by considering one parameter criteria, many sporadics are not classified properly therefore two parameter approach was proposed.

Targeting quasar candidates is always an important task for large spectroscopic sky survey projects. Astronomers never give up thinking out effective approaches to separate quasars from stars. The previous methods on this issue almost belong to supervised methods or color-color cut. In this work, we compare the performance of a supervised method – Support Vector Machine (SVM)– with that of an unsupervised method one-class SVM. The performance of SVM is better than that of one-class SVM. But one-class SVM is an unsupervised algorithm which is helpful to recognize rare or mysterious objects. Combining supervised methods with unsupervised methods is effective to improve the performance of a single classifier.

We use measurements of the rotation curve of the Milky Way by the tangent point method to reconstruct the density model of the Milky Way. The observed inner rotation curve is fitted by a theoretical density model, consisting of a Dehnen bulge, an exponential disc with a hole, and a flattened dark matter halo with a cored isothermal or NFW density profile. The density model is also set to be consistent with the local density constraints in the solar neighborhood.

How environment shapes galaxies on groups scale in the early universe is poorly constrained. Here we carry out a study of the colour properties of galaxies against environment using Pan-STARRS medium deep (PS1 MD) survey data. We first focus on the MD04 field which overlays with the COSMOS field with published photo-z and group catalogs. Photo-z with the accuracy of Δz/(1+z) ~ 0.058 for 0.36 million galaxies are derived based on PS1 photometry and CFHT-u. Together with a probabilistic-based group finder, PFOF, we are able to identify galaxy groups and find a 83%-86% matching rate with the X-ray groups (George et al. 2011) or spectroscopically selected groups (Knobel et al. 2012) with intermediate redshift (z ~ 0.7). Among the matched samples (see Fig. 1), we found the colours of BCGs to be indistinguishable from other members, but group galaxies tend to be redder than those in the field for a given range of z-band magnitude, suggesting environmental effects on the evolutionary history of galaxies. This is qualitatively consistent with the X-ray study (George et al. 2011). The rest-frame quantities, e.g. colours, stellar mass and star formation rates, will be included and expanded to larger MD fields (~ 70 deg2) to probe the cosmic evolution of galaxy properties in a forthcoming study.

We discuss the yields from Asymptotic Giant Branch stars, depending on their mass and metallicity. In agreement with previous investigations, we find that the extent of Hot Bottom Burning increases with mass. The yields of models with chemistry typical of high–metallicity Globular Clusters, i.e. Z = 0.008, show only a modest depletion of magnesium, and an oxgen depletion of ~ 0.4 dex. Low–metallicity yields show a much stronger magnesium depletion, and a dramatic drop in the oxygen content, ~ 1.2dex smaller than the initial value. We suggest that the Globular Cluster NGC 2419 is a possible target to the hypothesis of the self–enrichment scenario of Globular Clusters by the winds of Asymptotic Giant Branch stars.

On 2011 July 14, a transient X-ray source, Swift J1822.3–1606, was detected by Swift BAT via its burst activities. It was subsequently identified as a new magnetar upon the detection of a pulse period of 8.4 s. Using follow-up RXTE, Swift, and Chandra observations, we have determined a spin-down rate of Ṗ ~ 3 × 10−13, implying a dipole magnetic field of ~ 5 × 1013 G, second lowest among known magnetars, although our timing solution is contaminated by timing noise. The post-outburst flux evolution is well modelled by surface cooling resulting from heat injection in the outer crust, although we cannot rule out other models. We measure an absorption column density similar to that of the open cluster M17 at 10′ away, arguing for a comparable distance of ~1.6 kpc. If confirmed, this could be the nearest known magnetar.

Below [Fe/H] = −3.0, there is an enormous range in [C/Fe]. We discuss the properties of C-rich ([C/Fe] > +0.7) and C-normal ([C/Fe] ≤ +0.7) stars in this regime, and suggest that there existed two different gas cooling channels in the very early Universe.

A full appreciation of the role played by gas metallicity (Z), star-formation rate (SFR), and stellar mass (M*) is fundamental to understanding how galaxies form and evolve. Using data from the SDSS–DR7 and the GAMA surveys we study the Fundamental Plane for star-forming galaxies. Our analysis allows us to confirm the existence of a Fundamental Plane, for which stellar mass = f(Z, SFR) in star-forming galaxies.

We use the Marcario Low Resolution Spectrograph (LRS) at the Hobby-Eberly-Telescope (HET) to study the kinematics of pseudobulges and classical bulges in 45 S0-Sc type galaxies in the nearby universe. Our high-resolution (instrumental σ ≈ 39 km s−1) spectra allo only to resolve the typical velocity dispersions of our targets but also to derive the h3 and h4 Gauss-Hermite moments. We demonstrate for the first time that purely kinematic diagnostics of the bulge dichotomy agree systematically with those based on Sérsic index. Low Sérsic index bulges have both increased rotational support (higher v/σ values) and on average lower central velocity dispersions. Pseudobulges have systematically shallower velocity dispersion profiles. The same correlation also holds when visual morphologies are used to diagnose bulge type. Finally, we present evidence for formerly undetected counter rotation in the two systems NGC 3945 and NGC 4736. With these, a total of 16% of the systems in or sample show signs for stellar counter rotation.