We present a study of the radial velocity offsets between AGN-related narrow emission lines and host-galaxy emission and absorption lines in Seyfert galaxies with observed redshifts less than 0.043. We find that 35% of the Seyferts in the sample show [O iii] emission lines with blueshifts with respect to their host galaxies exceeding 50 km s−1, whereas only 6% show redshifts this large, in qualitative agreement with most previous studies. We also find that a greater percentage of Seyfert 1 galaxies show blueshifts than Seyfert 2 galaxies. Using HST/STIS spatially-resolved spectra of the Seyfert 2 galaxy NGC 1068 and the Seyfert 1 galaxy NGC 4151, we generate geometric models of their narrow-line regions (NLRs) and inner galactic disks and show how these models can explain the blueshifted [O iii] emission lines in collapsed STIS spectra of these two Seyferts. We conclude that the combination of mass outflow of ionized gas in the NLR and extinction by dust in the inner disk (primarily in the form of dust spirals) is primarily responsible for the velocity offsets in Seyfert galaxies.

We demonstrate that quantifying the intrinsic variability of quasars by fitting individual structure function data pairs with a 2-parameter power law model separates quasars from contaminating variable and non-variable point sources with a completeness of 93% and a purity of 99%. This approach can be used to select quasar samples in surveys like that being performed by Pan-STARRS1, where the usual color selection of quasars is not possible due to a filter system that is too red.

Asteroids 3200 Phaethon and 196256 (2003 EH1) are connected with two major meteoroid streams, Geminids and Quadrantids, respectively. We have modeled the observed light curves and decelerations of Geminid and Quadrantid meteors and studied their spectra. In both cases, we have found typical bulk densities of about 2600 kg m−3, much larger than in cometary meteoroids. Sodium was partially lost from Geminids and Quadrantids due to solar heating. The Quadrantid material was therefore not hidden deep inside the parent body 1500 years ago, when the perihelion was low enough for sodium loss to occur.

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a large-scale, near-infrared (H-band), high-resolution (R ~ 30,000), high S/N (≳100) spectroscopic survey of Milky Way stellar populations. APOGEE will operate from 1.51–1.68μm, a region that includes useful absorption lines from at least fifteen chemical species including α, odd-Z, and iron peak elements. The APOGEE instrument has a novel design featuring 300 science fibers feeding light to a mosaiced VPH grating and a six-element camera encased in a liquid nitrogen-cooled cryostat. A three year bright-time observing campaign will enable APOGEE to observe approximately 100,000 red giants across the Galactic bulge, disk and halo.

Abundance anomalies observed in globular cluster stars indicate pollution with material processed by hydrogen burning. Two main sources have been suggested: asymptotic giant branch (AGB) stars and massive stars rotating near the break-up limit (spin stars). We discuss the idea that massive binaries may provide an interesting alternative source of processed material. We discuss observational evidence for mass shedding from interacting binaries. In contrast to the fast, radiatively driven winds of massive stars, this material is typically ejected with low velocity. We expect that it remains inside the potential well of a globular cluster and becomes available for the formation or pollution of a second generation of stars. We estimate that the amount of processed low-velocity material that can be ejected by massive binaries is larger than the contribution of the two previously suggested sources combined.

The large burst of complex type which occurred at the metric, decimetric and microwave wavelengths from 0203 to 0304 UT on 2004 November 10 is analyzed in this present article, some prominent features of this event are obtained from the correlative analysis of this event with the Hα flare and coronal mass ejection (CME) and the radiation process of this event is discussed based on these observational features.

We present FLAMES/GIRAFFE spectroscopy obtained with the Very Large Telescope (VLT). Using these observations, we have been able (for the first time) to observe the Lii doublet in the main-sequence (MS) stars of a globular cluster. We also observed Li in a sample of subgiant (SG) stars of the same B − V colour. Our final sample is composed of 84 SG and 79 MS stars. In spite of the fact that SG and MS stars span the same temperature range, we find that the equivalent widths of the Lii doublet in SG stars are systematically greater than in MS stars, suggesting a higher Li content among SG stars. This is confirmed by our quantitative analysis, which makes use of both 1D and 3D model atmospheres. We find that SG stars show, on average, a higher Li abundance, by 0.1 dex, than MS stars. We also detect a positive slope of Li abundance with effective temperature: the higher the temperature the higher the Li abundance, both for SG and MS stars, although the slope is slightly steeper for MS stars. These results provide unambiguous evidence that the Li abundance changes with evolutionary state. The physical mechanisms that contribute to this are not yet clear, since none of the proposed models seem to describe accurately the observations. Whether such a mechanism can explain the cosmological lithium problem is still an open question.

Various studies have shown that there is an empirical relation between the nebular metallicity of a galaxy and its stellar mass. Until now, most studies of the mass-metallicity relation (M–Z) have focused on the abundances of the interstellar medium as measured by emission-line features. This technique thus excludes galaxies with AGN from the working samples, due to the difficulty to measure the nebular abundances when emission-lines are powered both by stars and AGN. With our synthesis code starlight, we are able to recover the stellar metallicities of galaxies from the Sloan Digital Sky Survey (SDSS). Therefore, although we still cannot measure the nebular metallicity in AGN hosts, we know their present-day stellar metallicities. Moreover, because we measure the metallicity of stellar populations of different ages in a galaxy, we are also able also recover the history of its chemical enrichment.

Icy plumes venting from Enceladus draw obvious comparisons to such features seen in comets. This paper outlines a consistent evolution from cometary activity to larger icy bodies in the outer solar system. The major differences are due to the systematic effects of increased gravity, including more spherical solid bodies (self-gravity), less porosity, the possible existence of liquid water due to internal sources of heat (Enceladus) versus possible cometary cyrovolcanism, internal inhomogeneities leading to jet-like features, and the possibility of a quasi-bound dusty gas atmosphere, as opposed to the extensive exospheres of comets. Similarities exist also, including gas and dust emission and the filamentary nature of jet-like features (caused by surface topography in comets), surface evolution by dust accumulation, heat and gas transport through the surface layers, among others. Initial results regarding the plume chemistry and comparisons to CAPS ion data show similarities too. Others have considered additional effects such as, charging of particles, micrometeorite impacts and complex interactions with the E-ring neutrals and plasma in great detail so these topics remain outside the scope of this paper.

We numerically investigate the long-term dynamics of the Saturn's small satellites Methone (S/2004 S1), Anthe (S/2007 S4) and Pallene (S/2004 S2). In our numerical integrations, these satellites are disturbed by non-spherical shape of Saturn and the six nearest regular satellites. The stability of the small bodies is studied here by analyzing long-term evolution of their orbital elements.

We show that long-term evolution of Pallene is dictated by a quasi secular resonance involving the ascending nodes (Ω) and longitudes of pericentric distances (ϖ) of Mimas (subscript 1) and Pallene (subscript 2), which critical argument is ϖ2−ϖ1−Ω1+Ω2. Long-term orbital evolution of Methone and Anthe are probably chaotic since: i) their orbits randomly cross the orbit of Mimas in time scales of thousands years); ii) long-term numerical simulations involving both small satellites are strongly affected by small changes in the initial conditions.

Here we derive a formulation connecting the observed variations of the solar diameter to the heliophysics of the photosphere, in particular in connection to the granulation pattern and morphology. The results from the measurements are next used to correlate the variations of the semi-diameter and of estimators of the solar activity along the solar cycle 23. The values obtained strongly support a broader physical description of the photosphere, intertwining the diameter variations with the irradiance, the sunspots, the 10.7 cm radio emission, and to a lesser degree with the integrated magnetic field and with the flares count.

We investigated the use of support vector machines (SVMs) to distinguish quasars from stars using survey databases from different wavebands. We first employed a random forest approach for selection and weighting of features. We find that SVMs are an effective method to preselect quasar candidates from multiwavelength data.

A star that wanders too close to a massive black hole (BH) is shredded by the BH's tidal gravity. Stellar gas falls back to the BH, releasing a flare of energy. In anticipation of upcoming transient surveys, we predict the light curves and spectra of tidal flares as a function of time, highlighting the unique signatures of tidal flares in the optical and near-IR. Some of the gas initially bound to the BH is likely blown away when the fallback rate is super-Eddington at early times. This outflow produces an optical luminosity comparable to that of a supernova (Figure 1, left panel); such events have durations of ~ 10 days and may have been missed in supernova searches that exclude the nuclear regions of galaxies. When the fallback rate subsides below Eddington, the gas accretes onto the BH via a thin disk whose emission peaks in the UV to soft X-rays. Some of this emission is reprocessed by the unbound stellar debris, producing a spectrum of very broad emission lines, with no corresponding narrow forbidden lines (center panel). These lines are strongest for BHs with MBH ~ 105–106M⊙ and thus optical surveys are particularly sensitive to the lowest mass BHs in galactic nuclei. Calibrating our models to ROSAT and GALEX observations, we predict detection rates for Pan-STARRS, Palomar Transit Factory, and LSST (right panel) and highlight observational challenges in the optical. Pan-STARRS should detect at least several events per year — many more if current theoretical models of super-Eddington outflows are correct. These surveys will significantly improve our knowledge of stellar dynamics in galactic nuclei, the physics of super-Eddington accretion, the demography of intermediate mass BHs, and the role of tidal disruption in the growth of massive BHs.

We obtained the Hα images of some solar active regions and prominences. Our astronomical observatory has the telescope-coronagraph which was equipped with the birefringent Halle Hα filter and CCD camera Apogee U4 (2048x2048 pixels). This paper presents multifractal spectra of images of some solar active regions in Hα line obtained with the coronagraph. The Pointwise Hoelder exponents (α) and Hausdorff spectrum fn(α) for a part of chromosphere with active region and without it, have been obtained. It is visible, that curves fn(α) for quiet and active regions of chromosphere differ very strongly. In particular, fn(α) for region with a sunspot and flare has very complicated form, and for region with filament the curves do not considerably differ from quiet chromosphere. The multifractal spectrum of quiet chromosphere shows that the quiet chromosphere is very well described by fractals with different dimensions. We analyze this result.

In the study of open clusters, the distinction between cluster and field members and the assignment of membership probabilities for each individual star in the relevant region are central issues. Here, we present an analysis based on the use of a fully automated method that relies on a hybrid heuristics, based on genetic algorithms and hill-climbing optimisation, as well as different probability distribution functions for the observables. We analysed the use of some variations for the parameterisation of those distribution functions. Finally, a catalogue comprising kinematic parameters and associated membership probability lists for all the open clusters in the Bordeaux PM2000 region was derived.

At high-z the most superdense massive galaxies are supposed to be the result of gas-rich mergers resulting in compact remnant (Khochfar & Silk (2006); Naab et al. (2007)). After this, dry mergers are expected to be the mechanism that moves these very massive galaxies towards the current stellar mass size relation. Whitin these merging scenarios, a non-negligible fraction (1-10%) of these galaxies is expected to survive since that epoch retaining their compactness and presenting old stellar populations in the past universe.Using the NYU Value-Added Galaxy Catalog (DR6), we find only a tiny fraction of galaxies (~0.03%) with re ≤ 1.5 kpc and M* ≥ 8x1010M⊙ in the local Universe (z~0.2). Surprisingly, they are relatively young (~2Gyr) and metal rich ([Z/H]~0.2) These results have been published in Trujillo et al. (2009)

We discuss possibility of observations of the warm-hot intergalactic medium using the hyperfine structure line of highly charged nitrogen ion 14N VII (rest wavelength λ = 5.652 mm). Observations of this line will allow to separate bulk and turbulent motions in the observed target and will broaden the information about the gas ionization state, chemical and isotopic composition.

Wavelength of this line is well-suited for ground-based observation of objects at z ≈ 0.15 − 0.6 when it is redshifted to the widely-used 6.5 − 9 mm spectral band, and, for example, for z ≥ 1.3, when the line can be observed in 1.3 cm band and at lower frequencies.

SMART is a model to derive both star formation history and chemical evolution simultaneously from color-magnitude diagrams of resolved stars in a galaxy. We present current progress and discuss the prospects of SMART for the next decade.

The majority of stars in the Galactic field and halo are part of binary or multiple systems. A significant fraction of these systems have orbital separations in excess of thousands of astronomical units, and systems wider than a parsec have been identified in the Galactic halo. These binary systems cannot have formed through the ‘normal’ star-formation process, nor by capture processes in the Galactic field. We propose that these wide systems were formed during the dissolution phase of young star clusters. We test this hypothesis using N-body simulations of evolving star clusters and find wide binary fractions of 1–30%, depending on initial conditions. Moreover, given that most stars form as part of a binary system, our theory predicts that a large fraction of the known wide ‘binaries’ are, in fact, multiple systems.

NGC 4852 is a moderately compact cluster centered at α2000 = 13 : 00 : 09; δ = −59 : 36 : 48, located near the center of an Hα superring. This cluster forms part of an extended region including young stellar aggregates inside a circle with a radius of 3 degrees, where many show an abundance of emission line stars. In the field of this cluster, two stars of known type exist: Wray 15–1039 (emission-line object) and CD −58:4845 (emission-line star). We do not yet know whether the Be phase is transient or whether it is just what randomly happens in some hot stars. It appears that Be star may be found even in clusters as old as 70 Myr with a high occurrence rate in clusters of 25–27 Myr old. A recent photometric survey in NGC 4852 down to V = 22 – 23 mag established that NGC 4852 is about 200 – 250 Myr old, located at 1.1 kpc from the Sun and with a mean E(B − V) = 0.45 mag. Since the presence of potential Be-type stars in the cluster area suggests it may be a very young object instead of moderately old, we decided to carry out spectroscopy for 33 selected stars and CCD UBVI photometry for the bright objects in the cluster area. This way, we attempt to clarify their evolutionary state and include them in the framework of emission-line stars and open clusters. From our analysis, we agree with the cluster distance and reddening determined by earlier studies, but we derive that the age of NGC 4852 is younger than 40 Myr.