The Shape and Profile of the Milky Way Halo as Seen by the Canada-France-Hawaii Telescope Legacy Survey

We use Canada-France-Hawaii Telescope Legacy Survey data for 170 deg^2, recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system, to study the distribution of near-turnoff main-sequence stars in the Galactic halo along four lines of sight to heliocentric distances of ~35 kpc. We find that the halo stellar number density profile becomes steeper at Galactocentric distances greater than R_(gal) ~ 28 kpc, with the power-law index changing from n_(inner) = –2.62 ± 0.04 to n_(outer) = –3.8 ± 0.1. In particular, we test a series of single power-law models and find them to be strongly disfavored by the data. The parameters for the best-fit Einasto profile are n = 2.2 ± 0.2 and R_e = 22.2 ± 0.4 kpc. We measure the oblateness of the halo to be q ≡ c/a = 0.70 ± 0.01 and detect no evidence of it changing across the range of probed distances. The Sagittarius stream is detected in the l = 173° and b = –62° direction as an overdensity of [Fe/H] ~ -1.5 dex stars at R_(gal) ~ 32 kpc, providing a new constraint for the Sagittarius stream and dark matter halo models. We also detect the Monoceros stream as an overdensity of [Fe/H] > -1.5 dex stars in the l = 232° and b = 26° direction at R_(gal) ≲ 25 kpc. In the two sight lines where we do not detect significant substructure, the median metallicity is found to be independent of distance within systematic uncertainties ([Fe/H] ~ -1.5 ± 0.1 dex)

The Gaia-LSST Synergy

We discuss the synergy of Gaia and the Large Synoptic Survey Telescope (LSST) in the context of Milky Way studies. LSST can be thought of as Gaia's deep complement because the two surveys will deliver trigonometric parallax, proper-motion, and photometric measurements with similar uncertainties at Gaia's faint end at $r=20$, and LSST will extend these measurements to a limit about five magnitudes fainter. We also point out that users of Gaia data will have developed data analysis skills required to benefit from LSST data, and provide detailed information about how international participants can join LSST.Comment: Presented at "The Milky Way Unravelled by Gaia", Barcelona, Dec 1-5, 2014; 7 pages, 1 color figur

Infrared Emission and Dynamics of Outlfows in Late-Type Stars

The dynamical structure and infrared emission of winds around late-type stars are studied in a self-consistent model that couples the equations of motion and radiative transfer. Thanks to its scaling properties, both the dynamics and IR spectrum of the solution are fully characterized by τF, the flux-averaged optical depth of the wind. Five types of dust grains are considered: astronomical silicate, crystalline olivine, graphite, amorphous carbon and SiC, as well as mixtures. Analysis of infrared signatures provides constraints on the grain chemical composition and indications for the simultaneous existence of silicate and carbon grains. The abundances of crystalline olivine in Si-dominated grains and of SiC in C-dominated grains are found to be limited to ≲ 20%-30%. Furthermore, in carbonaceous grains carbon is predominantly in amorphous form, rather than graphite. In mixtures, carbonaceous grains tend to dominate the dynamic behavior while silicate and SiC grains dominate the IR signature. The region of parameter space where radiation pressure can support a given mass-loss rate is identified, replacing the common misconception Mν ≲ L*/c, and it shows that radiatively driven winds explain the highest mass-loss rates observed to date. A new method to derive mass-loss rates from IR data is presented, and its results agree with other determinations. The theoretical spectra and colors are in good agreement with observations. IRAS Low Resolution Spectrometer classes are associated with τF for various grain materials and the regions of color-color diagrams expected to be populated by late-type stars are identified. For a given grain composition, location in the color-color diagram follows a track with position along the track determined by τF. We show that cirrus emission can severely affect point source measurements to the extent that their listed IRAS long-wavelength fluxes are unreliable. Whenever the listed IRAS flag cirr3 exceeds the listed 60 μm flux by more than a factor of 2, the 60 and 100 μm fluxes are no longer indicative of the underlying point source. After accounting of cirrus contamination, essentially all IRAS point sources (95%) located in the relevant regions of the color-color diagrams can be explained as late-type stars. There is no need to invoke time dependent effects, such as detached shells, for example, to explain either the colors or mass-loss rates of these sources. Although various indications of time varying mass-loss rates exist in numerous sources, the infrared properties of this class of stars are well explained as a whole with steady state shows

HYDRAULISCH-HYDROLOGISCHE SYNTHESE DES AUSFLUSSES DER KARSTQUELLE GOLUBINKA

Prikazana je hidrauličko-hidrološka analiza i rezultati hidrograma istjecanja za krški izvor Golubinka, što obuhvaća razdoblje 7. rujna 2012. do 1. listopada 2013. Cilj je bio stjecanje uvida u procese koji se javljaju na slivnom području izvora Golubinka, u smislu količine istjecanja, razina podzemne vode i procjeđivanja unutar krškog vodonosnika, u odnosu na količinu oborina izmjerenih tijekom analiziranog razdoblja. Na osnovi dvaju pristupa određen je odgovarajući koeficijent turbulentnog procjeđivanja kroz krške kanale analiziranog vodonosnika koji se potom može koristiti u numeričkom modeliranju.The hydraulic-hydrology analysis and discharge hydrograph results for the Golubinka karst spring are presented for the period from 7 September 2012 to 1 October 2013. The objective was to gain insight into processes occurring in the Golubinka spring drainage area, in terms of quantities of discharge, groundwater levels, and seepage within the karst aquifer, as related to the precipitation measured during the analysed period. An appropriate coefficient of turbulent seepage through karst channels in the analysed aquifer was determined based on two approaches. This coefficient can subsequently be used in numerical modelling.Dargestellt werden die hydraulisch-hydrologische Analyse und die Ergebnisse des Hydrogramms des Ausflusses für die Karstquelle Golubinka, was den Zeitraum vom 7. September 2012 bis zum 1. Oktober 2013 umfasst. Das Ziel war es, Einblick in die Prozesse zu erlangen, die im Wassersammelgebiet der Quelle Golubinka im Sinne der Ausflussmenge, des Grundwasserniveaus und der Filterung innerhalb des Karstgrundwasserleiters auftreten, im Vergleich zur Niederschlagsmenge, die während des analysierten Zeitraums gemessen wurde. Aufgrund zweier Ansätze wurde ein entsprechender Koeffizient der turbulenten Filterung durch die Karstkanäle des analysierten Grundwasserleiters festgelegt, der dann bei der nummerischen Modellierung angewendet werden kann

Dust Emission from Active Galactic Nuclei

Unified schemes of active galactic nuclei require an obscuring dusty torus around the central source, giving rise to a Seyfert 1 line spectrum for pole-on viewing and Seyfert 2 characteristics in edge-on sources. Although the observed IR is in broad agreement with this scheme, the behavior of the 10 μm silicate feature and the width of the far-IR emission peak remained serious problems in all previous modeling efforts. We show that these problems find a natural explanation if the dust is contained in approximately five to 10 clouds along radial rays through the torus. The spectral energy distributions of both type 1 and type 2 sources are properly reproduced from different viewpoints of the same object if the optical depth of each cloud is ≳60 at visual wavelengths and if the clouds\u27 mean free path increases roughly in proportion to the radial distance

Dust Emission from Herbig AE/BE Stars: Evidence for Disks and Envelopes

Infrared and millimeter-wave emission from Herbig Ae/Be stars has produced conflicting conclusions regarding the dust geometry in these objects. We show that the compact dimensions of the millimeter-wave-emitting regions are a decisive indication for disks. But a disk cannot explain the spectral energy distribution unless it is embedded in an extended envelope that (1) dominates the IR emission and (2) provides additional disk heating on top of the direct stellar radiation. Detailed radiative transfer calculations based on the simplest model for envelope-embedded disks successfully fit the data from UV to millimeter wavelengths and show that the disks have central holes. This model also resolves naturally some puzzling results of IR imaging