40,963 research outputs found
The EDGE-CALIFA Survey: Interferometric Observations of 126 Galaxies with CARMA
We present interferometric CO observations, made with the Combined Array for Millimeter-wave Astronomy (CARMA) interferometer, of galaxies from the Extragalactic Database for Galaxy Evolution survey (EDGE). These galaxies are selected from the Calar Alto Legacy Integral Field Area (CALIFA) sample, mapped with optical integral field spectroscopy. EDGE provides good-quality CO data (3σ sensitivity before inclination correction, resolution ∼1.4 kpc) for 126 galaxies, constituting the largest interferometric CO survey of galaxies in the nearby universe. We describe the survey and data characteristics and products, then present initial science results. We find that the exponential scale lengths of the molecular, stellar, and star-forming disks are approximately equal, and galaxies that are more compact in molecular gas than in stars tend to show signs of interaction. We characterize the molecular-to-stellar ratio as a function of Hubble type and stellar mass and present preliminary results on the resolved relations between the molecular gas, stars, and star-formation rate. We then discuss the dependence of the resolved molecular depletion time on stellar surface density, nebular extinction, and gas metallicity. EDGE provides a key data set to address outstanding topics regarding gas and its role in star formation and galaxy evolution, which will be publicly available on completion of the quality assessment.Fil: Bolatto, Alberto. University of Maryland; Estados UnidosFil: Wong, Tony. University of Illinois at Urbana; Estados UnidosFil: Utomo, Dyas. University of California at Berkeley; Estados UnidosFil: Blitz, Leo. University of California at Berkeley; Estados UnidosFil: Vogel, Stuart N.. University of Maryland; Estados UnidosFil: Sánchez, Sebastián F.. Universidad Nacional Autónoma de México; MéxicoFil: Barrera-Ballesteros, Jorge. University Johns Hopkins; Estados UnidosFil: Cao, Yixian. University of Illinois; Estados UnidosFil: Colombo, Dario. Max Planck Institut Fur Radioastronomie; AlemaniaFil: Dannerbauer, Helmut. Universidad de La Laguna; EspañaFil: García-Benito, Rubén. Instituto de Astrofísica de Andalucía; EspañaFil: Herrera-Camus, Rodrigo. Max Planck Institute für Extraterrestrische Physik; AlemaniaFil: Husemann, Bernd. Max-Planck-Institut für Astronomie; AlemaniaFil: Kalinova, Veselina. Max Planck Institut für Radioastronomie; AlemaniaFil: Leroy, Adam K.. Ohio State University; Estados UnidosFil: Leung, Gigi. Max-Planck-Institut für Astronomie; AlemaniaFil: Levy, Rebecca C.. University of Maryland; Estados UnidosFil: Mast, Damian. Observatorio Astronomico de la Universidad Nacional de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ostriker, Eve. University of Princeton; Estados UnidosFil: Rosolowsky, Erik. University of Alberta; CanadáFil: Sandstrom, Karin M.. University of California at San Diego; Estados UnidosFil: Teuben, Peter. University of Maryland; Estados UnidosFil: Van De Ven, Glenn. Max-Planck-Institut für Astronomie; AlemaniaFil: Walter, Fabian. Max-Planck-Institut für Astronomie; Alemani
Durchmusterung. Wieners Himmel
Norbert Wieners >Cybernetics> von 1948 geht aus von einem Vergleich zählender, durchmusternder Astronomie mit der neuen, statistikbasierten Meteorologie. Das Buch beginnt mit der ersten Strophe von >Weißt du vieviel Sternlein stehen<. ... Dieses Liedchen ist ein interessantes Thema für die Philosophie und die Geschichte der Wissenschaft, indem es zwei Wissenschaften nebeneinander stellt, die einerseits sich beide mit der Beobachtung des Himmels über uns beschäftigen, andererseits aber beinahe in jeder Beziehung höchst gegensätzlich sind. Die Astronomie ist die älteste der Wissenschaften, während die Meteorologie zu den jüngsten zählt, die erst anfangen, den Namen zu verdienen. ..
Large grains can grow in circumstellar discs
We perform coagulation & fragmentation simulations to understand grain growth
in T Tauri & brown dwarf discs. We present a physically-motivated approach
using a probability distribution function for the collision velocities and
separating the deterministic & stochastic velocities. We find growth to larger
sizes compared to other models. Furthermore, if brown dwarf discs are
scaled-down versions of T Tauri discs (in terms of stellar & disc mass, and
disc radius), growth at the same location with respect to the outer edge occurs
to similar sizes in both discs.Comment: Submitted to the conference proceedings of the IAU Symposium 299 -
Exploring the formation and evolution of planetary systems. 2 pages; 2
figure
Interferometric Detection of Planets/Gaps in Protoplanetary Disks
We investigate the possibility to find evidence for planets in circumstellar
disks by infrared and submillimeter interferometry. Hydrodynamical simulations
of a circumstellar disk around a solar-type star with an embedded planet of 1
Jupiter mass are presented. On the basis of 3D radiative transfer simulations,
images of this system are calculated. These intensity maps provide the basis
for the simulation of the interferometers VLTI (equipped with the mid-infrared
instrument MIDI) and ALMA. While ALMA will provide the necessary basis for a
direct gap and therefore indirect planet detection, MIDI/VLTI will provide the
possibility to distinguish between disks with or without accretion on the
central star on the basis of visibility measurements.Comment: 4 pages, TeX (or Latex, etc); to appear in proceedings of "Scientific
Frontiers in Research on Extrasolar Planets
Spectroscopic characterisation of CARMENES target candidates from FEROS, CAFE and HRS high-resolution spectra
CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with
Near-infrared and optical Echelle Spectrographs) started a new planet survey on
M-dwarfs in January this year. The new high-resolution spectrographs are
operating in the visible and near-infrared at Calar Alto Observatory. They will
perform high-accuracy radial-velocity measurements (goal 1 m s-1) of about 300
M-dwarfs with the aim to detect low-mass planets within habitable zones. We
characterised the candidate sample for CARMENES and provide fundamental
parameters for these stars in order to constrain planetary properties and
understand star-planet systems. Using state-of-the-art model atmospheres
(PHOENIX-ACES) and chi2-minimization with a downhill-simplex method we
determine effective temperature, surface gravity and metallicity [Fe/H] for
high-resolution spectra of around 480 stars of spectral types M0.0-6.5V taken
with FEROS, CAFE and HRS. We find good agreement between the models and our
observed high-resolution spectra. We show the performance of the algorithm, as
well as results, parameter and spectral type distributions for the CARMENES
candidate sample, which is used to define the CARMENES target sample. We also
present first preliminary results obtained from CARMENES spectra
Über Wert und Bedeutung der Mathematik : Vortrag / gehalten am 15. März 1845 im Wissenschaftlichen Verein zu Berlin von Karl Schellbach. Elektronische Ausgabe von Gabriele Dörflinger
,,Die Mathematik kann zwar der Rechenkunst nicht entbehren, aber sie gelangt nicht durch sie zu ihren wichtigsten Resulten.''
Der Autor beschreibt in dem Vortrag die wichtigsten mathematischen Methoden und ihre Anwendung vor allem in Physik und Astronomie
Green Open Access in Mathematik und Astronomie
Taubert NC. Green Open Access in Mathematik und Astronomie. In: Parthey H, Umstätter W, eds. Forschung und Publikation in der Wissenschaft. Jahrbuch Wissenschaftsforschung. Vol 2013. Berlin: Wissenschaftlicher Verlag Berlin (wVB); 2014: 42-75
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