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Astrop | The Spitzer c2d Survey of Large, Nearby, Insterstellar Clouds. IX. The Serpens YSO Population As Observed With IRAC and MIPS | We discuss the results from the combined IRAC and MIPS c2d Spitzer Legacy observations of the Serpens star-forming region. In particular we present a set of criteria for isolating bona fide young stellar objects, YSO's, from the extensive background contamination by extra-galactic objects. We then discuss the propertie... |
Astrop | Spectroscopic Observations of the Intermediate Polar EX Hydrae in Quiescence | Results from spectroscopic observations of the Intermediate Polar (IP) EX Hya in quiescence during 1991 and 2001 are presented. Spin-modulated radial velocities consistent with an outer disc origin were detected for the first time in an IP. The spin pulsation was modulated with velocities near ~500-600 km/s. These velo... |
Astrop | ALMA as the ideal probe of the solar chromosphere | The very nature of the solar chromosphere, its structuring and dynamics, remains far from being properly understood, in spite of intensive research. Here we point out the potential of chromospheric observations at millimeter wavelengths to resolve this long-standing problem. Computations carried out with a sophisticate... |
Astrop | Astrophysical gyrokinetics: kinetic and fluid turbulent cascades in magnetized weakly collisional plasmas | We present a theoretical framework for plasma turbulence in astrophysical plasmas (solar wind, interstellar medium, galaxy clusters, accretion disks). The key assumptions are that the turbulence is anisotropic with respect to the mean magnetic field and frequencies are low compared to the ion cyclotron frequency. The e... |
Astrop | Inference on white dwarf binary systems using the first round Mock LISA Data Challenges data sets | We report on the analysis of selected single source data sets from the first round of the Mock LISA Data Challenges (MLDC) for white dwarf binaries. We implemented an end-to-end pipeline consisting of a grid-based coherent pre-processing unit for signal detection, and an automatic Markov Chain Monte Carlo post-processi... |
Astrop | The Mass and Radius of the Unseen M-Dwarf Companion in the Single-Lined Eclipsing Binary HAT-TR-205-013 | We derive masses and radii for both components in the single-lined eclipsing binary HAT-TR-205-013, which consists of a F7V primary and a late M-dwarf secondary. The system's period is short, $P=2.230736 \pm 0.000010$ days, with an orbit indistinguishable from circular, $e=0.012 \pm 0.021$. We demonstrate generally tha... |
Astrop | Shaping the Globular Cluster Mass Function by Stellar-Dynamical Evaporation | We show that the globular cluster mass function (GCMF) in the Milky Way depends on cluster half-mass density (rho_h) in the sense that the turnover mass M_TO increases with rho_h while the width of the GCMF decreases. We argue that this is the expected signature of the slow erosion of a mass function that initially ros... |
Astrop | Timing and Lensing of the Colliding Bullet Clusters: barely enough time and gravity to accelerate the bullet | We present semi-analytical constraint on the amount of dark matter in the merging bullet galaxy cluster using the classical Local Group timing arguments. We consider particle orbits in potential models which fit the lensing data. {\it Marginally consistent} CDM models in Newtonian gravity are found with a total mass M_... |
Astrop | An online repository of Swift/XRT light curves of GRBs | Context. Swift data are revolutionising our understanding of Gamma Ray Bursts. Since bursts fade rapidly, it is desirable to create and disseminate accurate light curves rapidly. Aims. To provide the community with an online repository of X-ray light curves obtained with Swift. The light curves should be of the quality... |
Astrop | PAH emission and star formation in the host of the z~2.56 Cloverleaf QSO | We report the first detection of the 6.2micron and 7.7micron infrared `PAH' emission features in the spectrum of a high redshift QSO, from the Spitzer-IRS spectrum of the Cloverleaf lensed QSO (H1413+117, z~2.56). The ratio of PAH features and rest frame far-infrared emission is the same as in lower luminosity star for... |
Astrop | Circular and non-circular nearly horizon-skimming orbits in Kerr spacetimes | We have performed a detailed analysis of orbital motion in the vicinity of a nearly extremal Kerr black hole. For very rapidly rotating black holes (spin a=J/M>0.9524M) we have found a class of very strong field eccentric orbits whose angular momentum L_z increases with the orbit's inclination with respect to the equat... |
Astrop | The Blue Straggler Population of the Globular Cluster M5 | By combining high-resolution HST and wide-field ground based observations, in ultraviolet and optical bands, we study the Blue Stragglers Star (BSS) population of the galactic globular cluster M5 (NGC 5904) from its very central regions up to its periphery. The BSS distribution is highly peaked in the cluster center, d... |
Astrop | Eternal inflation and localization on the landscape | We model the essential features of eternal inflation on the landscape of a dense discretuum of vacua by the potential $V(\phi)=V_{0}+\delta V(\phi)$, where $|\delta V(\phi)|\ll V_{0}$ is random. We find that the diffusion of the distribution function $\rho(\phi,t)$ of the inflaton expectation value in different Hubble ... |
Astrop | A computer program for fast non-LTE analysis of interstellar line spectra | The large quantity and high quality of modern radio and infrared line observations require efficient modeling techniques to infer physical and chemical parameters such as temperature, density, and molecular abundances. We present a computer program to calculate the intensities of atomic and molecular lines produced in ... |
Astrop | Nonlinear force-free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation | This paper has been withdrawn by the authors. |
Astrop | Oxygen-rich droplets and the enrichment of the ISM | We argue that the discrepancies observed in HII regions between abundances derived from optical recombination lines (ORLs) and collisionally excited lines (CELs) might well be the signature of a scenario of the enrichment of the interstellar medium (ISM) proposed by Tenorio-Tagle (1996). In this scenario, the fresh oxy... |
Astrop | Radiative losses and cut-offs of energetic particles at relativistic shocks | We investigate the acceleration and simultaneous radiative losses of electrons in the vicinity of relativistic shocks. Particles undergo pitch angle diffusion, gaining energy as they cross the shock by the Fermi mechanism and also emitting synchrotron radiation in the ambient magnetic field. A semi-analytic approach is... |
Astrop | Discovery of a point-like very-high-energy gamma-ray source in Monoceros | The complex Monoceros Loop SNR/Rosette Nebula region contains several potential sources of very-high-energy (VHE) gamma-ray emission and two as yet unidentified high-energy EGRET sources. Sensitive VHE observations are required to probe acceleration processes in this region. The H.E.S.S. telescope array has been used t... |
Astrop | Solar System Constraints on Gauss-Bonnet Mediated Dark Energy | Although the Gauss-Bonnet term is a topological invariant for general relativity, it couples naturally to a quintessence scalar field, modifying gravity at solar system scales. We determine the solar system constraints due to this term by evaluating the post-Newtonian metric for a distributional source. We find a mass ... |
Astrop | Gamma-ray emitting AGN and GLAST | I describe the different classes of Active Galactic Nuclei (AGN) and the basic tenets of unified schemes. I then review the properties of the extragalactic sources detected in the GeV and TeV bands, showing that the vast majority of them belong to the very rare blazar class. I further discuss the kind of AGN GLAST is l... |
Astrop | The transverse proximity effect in spectral hardness on the line of sight towards HE 2347-4342 | We report the discovery of 14 quasars in the vicinity of HE2347-4342, one of the two quasars whose intergalactic HeII forest has been resolved with FUSE. By analysing the HI and the HeII opacity variations separately, no transverse proximity effect is detected near three foreground quasars of HE2347-4342: QSOJ23503-432... |
Astrop | The Reliability on the Direction of the Incident Neutrino for the Fully Contained Events and Partially Contained Events due to QEL in the Super-Kamiokande | In the SK analysis of the neutrino events for [Fully Contained Events] and [Partially Contained Events] on their zenith angle distribution, it is assumed that the zenith angle of the incident neutrino is the same as that of the detected charged lepton. In the present paper, we examine the validity of [the SK assumption... |
Astrop | Star Formation in Galaxies with Large Lower Surface Brightness Disks | We present B, R, and Halpha imaging data of 19 large disk galaxies whose properties are intermediate between classical low surface brightness galaxies and ordinary high surface brightness galaxies. We use data taken from the Lowell 1.8m Perkins telescope to determine the galaxies' overall morphology, color, and star fo... |
Astrop | A Spitzer census of the IC 348 nebula | We present a Spitzer based census of the IC 348 nebula and embedded star cluster. Our Spitzer census supplemented by ground based spectra has added 42 class II T-Tauri sources to the cluster membership and identified ~20 class 0/I protostars. The population of IC 348 likely exceeds 400 sources after accounting statisti... |
Astrop | Discovery of X-ray emission from the young radio pulsar PSR J1357-6429 | We present the first X-ray detection of the very young pulsar PSR J1357-6429 (characteristic age of 7.3 kyr) using data from the XMM-Newton and Chandra satellites. We find that the spectrum is well described by a power-law plus blackbody model, with photon index Gamma=1.4 and blackbody temperature kT=160 eV. For the es... |
Astrop | Quark matter and the astrophysics of neutron stars | Some of the means through which the possible presence of nearly deconfined quarks in neutron stars can be detected by astrophysical observations of neutron stars from their birth to old age are highlighted. |
Astrop | Chandra Observations of Supernova 1987A | We have been monitoring Supernova (SN) 1987A with {\it Chandra X-Ray Observatory} since 1999. We present a review of previous results from our {\it Chandra} observations, and some preliminary results from new {\it Chandra} data obtained in 2006 and 2007. High resolution imaging and spectroscopic studies of SN 1987A wit... |
Astrop | Curvature and isocurvature perturbations in two-field inflation | We study cosmological perturbations in two-field inflation, allowing for non-standard kinetic terms. We calculate analytically the spectra of curvature and isocurvature modes at Hubble crossing, up to first order in the slow-roll parameters. We also compute numerically the evolution of the curvature and isocurvature mo... |
Astrop | The Radio Emission, X-ray Emission, and Hydrodynamics of G328.4+0.2: A Comprehensive Analysis of a Luminous Pulsar Wind Nebula, its Neutron Star, and the Progenitor Supernova Explosion | We present new observational results obtained for the Galactic non-thermal radio source G328.4+0.2 to determine both if this source is a pulsar wind nebula or supernova remnant, and in either case, the physical properties of this source. Using X-ray data obtained by XMM, we confirm that the X-ray emission from this sou... |
Astrop | The Return of a Static Universe and the End of Cosmology | We demonstrate that as we extrapolate the current $\Lambda$CDM universe forward in time, all evidence of the Hubble expansion will disappear, so that observers in our "island universe" will be fundamentally incapable of determining the true nature of the universe, including the existence of the highly dominant vacuum e... |
Astrop | Dark Matter annihilation in Draco: new considerations on the expected gamma flux | A new estimation of the gamma-ray flux that we expect to detect from SUSY dark matter annihilation from the Draco dSph is presented using the DM density profiles compatible with the latest observations. This calculation takes also into account the important effect of the Point Spread Function (PSF) of the telescope. We... |
Astrop | Magnetohydrodynamic Rebound Shocks of Supernovae | We construct magnetohydrodynamic (MHD) similarity rebound shocks joining `quasi-static' asymptotic solutions around the central degenerate core to explore an MHD model for the evolution of random magnetic field in supernova explosions. This provides a theoretical basis for further studying synchrotron diagnostics, MHD ... |
Astrop | Exploring First Stars Era with GLAST | Cosmic infrared background (CIB) includes emissions from objects inaccessible to current telescopic studies, such as the putative Population III, the first stars. Recently, strong direct evidence for significant CIB levels produced by the first stars came from CIB fluctuations discovered in deep Spitzer images. Such CI... |
Astrop | Correlated modulation between the redshifted Fe K alpha line and the continuum emission in NGC 3783 | It has been suggested that X-ray observations of rapidly variable Seyfert galaxies may hold the key to probe the gas orbital motions in the innermost regions of accretion discs around black holes and, thus, trace flow patterns under the effect of the hole strong gravitational field. We explore this possibility analizin... |
Astrop | Einstein vs Maxwell: Is gravitation a curvature of space, a field in flat space, or both? | Starting with a field theoretic approach in Minkowski space, the gravitational energy momentum tensor is derived from the Einstein equations in a straightforward manner. This allows to present them as {\it acceleration tensor} = const. $\times$ {\it total energy momentum tensor}. For flat space cosmology the gravitatio... |
Astrop | Two new basaltic asteroids in the Outer Main Belt? | The identification of basaltic asteroids in the asteroid Main Belt and the description of their surface mineralogy is necessary to understand the diversity in the collection of basaltic meteorites. Basaltic asteroids can be identified from their visible reflectance spectra and are classified as V-type in the usual taxo... |
Astrop | Comments on ``Are Swift Gamma-Ray Bursts consistent with the Ghirlanda relation?", by Campana et al.(astro--ph/0703676) | In their recent paper, Campana et al. (2007) found that 5 bursts, among those detected by Swift, are outliers with respect to the E_peak-E_gamma ("Ghirlanda") correlation. We instead argue that they are not. |
Astrop | Hydrodynamic and Spectral Simulations of HMXB Winds | We describe preliminary results of a global model of the radiatively-driven photoionized wind and accretion flow of the high-mass X-ray binary Vela X-1. The full model combines FLASH hydrodynamic calculations, XSTAR photoionization calculations, HULLAC atomic data, and Monte Carlo radiation transport. We present maps o... |
Astrop | Radio Astrometric Detection and Characterization of Extra-Solar Planets: A White Paper Submitted to the NSF ExoPlanet Task Force | The extraordinary astrometric accuracy of radio interferometry creates an important and unique opportunity for the discovery and characterization of exo-planets. Currently, the Very Long Baseline Array can routinely achieve better than 100 microarcsecond accuracy, and can approach 10 microarcsecond with careful calibra... |
Astrop | Masers and star formation | Recent observational and theoretical advances concerning astronomical masers in star forming regions are reviewed. Major masing species are considered individually and in combination. Key results are summarized with emphasis on present science and future prospects. |
Astrop | The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds VIII. Serpens Observed with MIPS | We present maps of 1.5 square degrees of the Serpens dark cloud at 24, 70, and 160\micron observed with the Spitzer Space Telescope MIPS Camera. More than 2400 compact sources have been extracted at 24um, nearly 100 at 70um, and 4 at 160um. We estimate completeness limits for our 24um survey from Monte Carlo tests with... |
Astrop | Modeling the three-point correlation function | We present new predictions for the galaxy three-point correlation function (3PCF) using high-resolution dissipationless cosmological simulations of a flat LCDM Universe which resolve galaxy-size halos and subhalos. We create realistic mock galaxy catalogs by assigning luminosities and colors to dark matter halos and su... |
Astrop | Multi-spectral Observations of Lunar Occultations: I. Resolving The Dust Shell Around AFGL 5440 | We present observations and modeling of a lunar occultation of the dust-enshrouded carbon star AFGL 5440. The observations were made over a continuous range of wavelengths from 1 - 4um with a high-speed spectrophotometer designed expressly for this purpose. We find that the occultation fringes cannot be fit by any sing... |
Astrop | Formation and Collisional Evolution of Kuiper Belt Objects | This chapter summarizes analytic theory and numerical calculations for the formation and collisional evolution of KBOs at 20--150 AU. We describe the main predictions of a baseline self-stirring model and show how dynamical perturbations from a stellar flyby or stirring by a giant planet modify the evolution. Although ... |
Astrop | Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5 | (Abridged) We compare recent results from X-ray, strong lensing, weak lensing, and optical observations with numerical simulations of the merging galaxy cluster 1E0657-56. X-ray observations reveal a bullet-like subcluster with a prominent bow shock, while lensing results show that the positions of the total mass peaks... |
Astrop | REM near-IR and optical multiband observations of PKS2155-304 in 2005 | Spectral variability is the main tool for constraining emission models of BL Lac objects. By means of systematic observations of the BL Lac prototype PKS 2155-304 in the infrared-optical band, we explore variability on the scales of months, days and hours. We made our observations with the robotic 60 cm telescope REM l... |
Astrop | Supernova Polarization and the Type IIn Classification | While the members of the Type IIn category of supernovae are united by the presence of strong multicomponent Balmer emission lines in their spectra, they are quite heterogeneous with respect to other properties such as Balmer line profiles, light curves, strength of radio emission, and intrinsic brightness. We are now ... |
Astrop | Near-Infrared Spectra of the Black Hole X-Ray Binary, A0620-00 | We present broadband NIR spectra of A0620-00 obtained with SpeX on the IRTF. The spectrum is characterized by a blue continuum on which are superimposed broad emission lines of HI and HeII and a host of narrower absorption lines of neutral metals and molecules. Spectral type standard star spectra scaled to the deredden... |
Astrop | Modeling the Spectral Energy Distribution and Variability of 3C 66A during the WEBT campaign of 2003 -- 2004 | The BL Lac object 3C 66A was observed in an extensive multiwavelength monitoring campaign from July 2003 till April 2004. The spectral energy distribution (SED) was measured over the entire electromagnetic spectrum, with flux measurements from radio to X-ray frequencies and upper limits in the very high energy (VHE) ga... |
Astrop | The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674 | Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates planet searches around stars which are significantly more massive or less massive than the Sun, and in particular our radial velocity search for planets around very-low mass stars. Methods: ... |
Astrop | A Comparison between Anomalous 6-cm H$_2$CO Absorption and CO(1-0) Emission in the L1204/S140 | We report observations of the dust cloud L1204 with the Onsala 25-m telescope in the 6 cm (1$_{11}-1_{10}$) transition of \htco. The observed region includes the S140 H${\alpha}$ arc. This spectral line is seen here in absorption against the cosmic microwave background, indicating the presence of widespread warm molecu... |
Astrop | A New Model For The Loop-I (The North Polar Spur) Region | The North Polar Spur (NPS) is the brightest filament of Loop I, a large circular feature in the radio continuum sky. In this paper, a model consisting of two synchrotron emitting shells is presented that reproduces large-scale structures revealed by recent polarization surveys. The polarized emission of the NPS is repr... |
Astrop | HI velocity dispersion in NGC 1058 | We present excellent resolution and high sensitivity Very Large Array (VLA) observations of the 21cm HI line emission from the face-on galaxy NGC 1058, providing the first reliable study of the HI profile shapes throughout the entire disk of an external galaxy. Our observations show an intriguing picture of the interst... |
Astrop | Common Envelope Evolution Redux | Common envelopes form in dynamical time scale mass exchange, when the envelope of a donor star engulfs a much denser companion, and the core of the donor plus the dense companion star spiral inward through this dissipative envelope. As conceived by Paczynski and Ostriker, this process must be responsible for the creati... |
Astrop | The Source of Turbulence in Astrophysical Disks: An Ill-posed Problem. | An critical overview of the current state of research in turbulence in astrophysical disks. |
Astrop | Search for Very High Energy Emission from Gamma-Ray Bursts using Milagro | Gamma-Ray Bursts (GRBs) have been detected at GeV energies by EGRET and models predict emission at > 100 GeV. Milagro is a wide field (2 sr) high duty cycle (> 90 %) ground based water Cherenkov detector that records extensive air showers in the energy range 100 GeV to 100 TeV. We have searched for very high energy emi... |
Astrop | The core binary fractions of star clusters from realistic simulations | We investigate the evolution of binary fractions in star clusters using N-body models of up to 100000 stars. Primordial binary frequencies in these models range from 5% to 50%. Simulations are performed with the NBODY4 code and include a full mass spectrum of stars, stellar evolution, binary evolution and the tidal fie... |
Astrop | Remnant evolution after a carbon-oxygen white dwarf merger | We systematically explore the evolution of the merger of two carbon-oxygen (CO) white dwarfs. The dynamical evolution of a 0.9 Msun + 0.6 Msun CO white dwarf merger is followed by a three-dimensional SPH simulation. We use an elaborate prescription in which artificial viscosity is essentially absent, unless a shock is ... |
Astrop | Parametrized Post-Newtonian Expansion of Chern-Simons Gravity | We investigate the weak-field, post-Newtonian expansion to the solution of the field equations in Chern-Simons gravity with a perfect fluid source. In particular, we study the mapping of this solution to the parameterized post-Newtonian formalism to 1 PN order in the metric. We find that the PPN parameters of Chern-Sim... |
Astrop | Measurement of the Aerosol Phase Function at the Pierre Auger Observatory | Air fluorescence detectors measure the energy of ultra-high energy cosmic rays by collecting fluorescence light emitted from nitrogen molecules along the extensive air shower cascade. To ensure a reliable energy determination, the light signal needs to be corrected for atmospheric effects, which not only attenuate the ... |
Astrop | Periodic accretion from a circumbinary disk in the young binary UZ Tau E | Close pre-main-sequence binary stars are expected to clear central holes in their protoplanetary disks, but the extent to which material can flow from the circumbinary disk across the gap onto the individual circumstellar disks has been unclear. In binaries with eccentric orbits, periodic perturbation of the outer disk... |
Astrop | VLBI observations of nineteen GHz-Peaked-Spectrum radio sources at 1.6 GHz | Aims and Methods: We present the results of VLBI observations of nineteen GHz-Peaked-Spectrum (GPS) radio sources at 1.6 GHz. Of them, 15 sources are selected from the Parkes Half Jansky (PHJ) sample (Snellen 2002), 4 others are from our previous observation list. We aimed at imaging the structure of GPS sources, searc... |
Astrop | Power Spectra to 1% Accuracy between Dynamical Dark Energy Cosmologies | For dynamical dark energy cosmologies we carry out a series of N-body gravitational simulations, achieving percent level accuracy in the relative mass power spectra at any redshift. Such accuracy in the power spectrum is necessary for next generation cosmological mass probes. Our matching procedure reproduces the CMB d... |
Astrop | Extra dimensions and Lorentz invariance violation | We consider effective model where photons interact with scalar field corresponding to conformal excitations of the internal space (geometrical moduli/gravexcitons). We demonstrate that this interaction results in a modified dispersion relation for photons, and consequently, the photon group velocity depends on the ener... |
Astrop | The Millennium Galaxy Catalogue: The local supermassive black hole mass function in early- and late-type galaxies | We provide a new estimate of the local supermassive black hole mass function using (i) the empirical relation between supermassive black hole mass and the Sersic index of the host spheroidal stellar system and (ii) the measured (spheroid) Sersic indices drawn from 10k galaxies in the Millennium Galaxy Catalogue. The ob... |
Astrop | The Blazar Spectral Sequence and GLAST | The present status and understanding of the "spectral sequence" of blazars is discussed in the perspective of the upcoming GLAST launch. The vast improvement in sensitivity will allow to i) determine more objectively the "average" gamma-ray properties of classes objects ii) probe more deeply the ratio between accretion... |
Astrop | Diffuse X-ray Emission from the Carina Nebula Observed with Suzaku | A number of giant HII regions are associated with soft diffuse X-ray emission. Among these, the Carina nebula possesses the brightest soft diffuse emission. The required plasma temperature and thermal energy can be produced by collisions or termination of fast winds from main-sequence or embedded young O stars, but the... |
Astrop | What can emission lines tell us? | 1 Generalities 2 Empirical diagnostics based on emission lines 3 Photoionization modelling 4 Pending questions 5 Appendix: Lists of useful lines and how to deal with them |
Astrop | Visible spectroscopic and photometric survey of Jupiter Trojans: final results on dynamical families | We present the results of a visible spectroscopic and photometric survey of Jupiter Trojans belonging to different dynamical families carried out at the ESO-NTT telescope. We obtained data on 47 objects, 23 belonging to the L5 swarm and 24 to the L4 one. These data together with those already published by Fornasier et ... |
Astrop | FIRST-based survey of Compact Steep Spectrum sources, V. Milliarcsecond-scale morphology of CSS objects | Multifrequency VLBA observations of the final group of ten objects in a sample of FIRST-based compact steep spectrum (CSS) sources are presented. The sample was selected to investigate whether objects of this kind could be relics of radio-loud AGNs switched off at very early stages of their evolution or possibly to ind... |
Astrop | Trigonometric parallaxes of high velocity halo white dwarf candidates | The status of 38 halo white dwarf candidates identified by Oppenheimer et al. (2001) has been intensively discussed by various authors. In analyses undertaken to date, trigonometric parallaxes are crucial missing data. Distance measurements are mandatory to kinematically segregate halo object from disk objects and henc... |
Astrop | AMR simulations of the low T/|W| bar-mode instability of neutron stars | It has been recently argued through numerical work that rotating stars with a high degree of differential rotation are dynamically unstable against bar-mode deformation, even for values of the ratio of rotational kinetic energy to gravitational potential energy as low as O(0.01). This may have implications for gravitat... |
Astrop | Torsional oscillations of longitudinally inhomogeneous coronal loops | We explore the effect of an inhomogeneous mass density field on frequencies and wave profiles of torsional Alfven oscillations in solar coronal loops. Dispersion relations for torsional oscillations are derived analytically in limits of weak and strong inhomogeneities. These analytical results are verified by numerical... |
Astrop | The collision velocity of the bullet cluster in conventional and modified dynamics | We consider the orbit of the bullet cluster 1E 0657-56 in both CDM and MOND using accurate mass models appropriate to each case in order to ascertain the maximum plausible collision velocity. Impact velocities consistent with the shock velocity (~ 4700km/s) occur naturally in MOND. CDM can generate collision velocities... |
Astrop | Low mass visual binaries in the solar neighbourhood: The case of HD141272 | We search for stellar and substellar companions of young nearby stars to investigate stellar multiplicity and formation of stellar and substellar companions. We detect common proper-motion companions of stars via multi-epoch imaging. Their companionship is finally confirmed with photometry and spectroscopy. Here we rep... |
Astrop | Modelling the Near-IR Spectra of Red Supergiant-dominated Populations | We report on recent progress in the modelling of the near-IR spectra of young stellar populations, i.e. populations in which red supergiants (RSGs) are dominant. First, we discuss the determination of fundamental parameters of RSGs using fits to their near-IR spectra with new PHOENIX model spectra; RSG-specific surface... |
Astrop | The Sigma-D Relation for Planetary Nebulae: Preliminary Analysis | An analysis of the relation between radio surface brightness and diameter, so-called Sigma-D relation, for planetary nebulae (PNe) is presented: i) the theoretical Sigma-D relation for the evolution of bremsstrahlung surface brightness is derived; ii) contrary to the results obtained earlier for the Galactic supernova ... |
Astrop | Limits on WIMP-nucleon interactions with CsI(Tl) crystal detectors | The Korea Invisible Mass Search(KIMS) experiment presents new limits on WIMP-nucleon cross section using the data from an exposure of 3409 kgd taken with low background CsI(Tl) crystals at Yangyang underground laboratory. The most stringent limit on the spin dependent interaction for pure proton case is obtained. The D... |
Astrop | Feedback from first radiation sources: H- photodissociation | During the epoch of reionization, the formation of radiation sources is accompanied by the growth of a H- photodissociating flux. We estimate the impact of this flux on the formation of molecular hydrogen and cooling in the first galaxies, assuming different types of radiation sources (e.g. Pop II and Pop III stars, mi... |
Astrop | Star Formation in the Bok Globule CB54 | We present mid-infrared (10.4 \micron, 11.7 \micron, and 18.3 \micron) imaging intended to locate and characterize the suspected protostellar components within the Bok globule CB54. We detect and confirm the protostellar status for the near-infrared source CB54YC1-II. The mid-infrared luminosity for CB54YC1-II was foun... |
Astrop | Fragmentation of general relativistic quasi-toroidal polytropes | We investigate the role of rotational instabilities in the context of black hole formation in relativistic stars. In addition to the standard scenario - an axially symmetric dynamical instability forming a horizon at the star's center - the recently found low-$T/|W|$ instabilities are shown to lead to fragmentation and... |
Astrop | Evidence for a planetary companion around a nearby young star | We report evidence for a planetary companion around the nearby young star HD 70573. The star is a G type dwarf located at a distance of 46 pc with age estimation between 20 and 300 Myrs. We carried out spectroscopic observations of this star with FEROS at the 2.2 m MPG/ESO telescope at La Silla. Our spectroscopic analy... |
Astrop | Giant Planet Migration in Viscous Power-Law Discs | Many extra-solar planets discovered over the past decade are gas giants in tight orbits around their host stars. Due to the difficulties of forming these `hot Jupiters' in situ, they are generally assumed to have migrated to their present orbits through interactions with their nascent discs. In this paper, we present a... |
Astrop | Dramatic Variability of X-ray Absorption Lines in the Black Hole Candidate Cygnus X-1 | We report results from a 30 ks observation of Cygnus X-1 with the High Energy Transmission Grating Spectrometer (HETGS) on board the {\em Chandra X-ray Observatory}. Numerous absorption lines were detected in the HETGS spectrum. The lines are associated with highly ionized Ne, Na, Mg, Al, Si, S, and Fe, some of which h... |
Astrop | An Extrasolar Planet Census with a Space-based Microlensing Survey | A space-based gravitational microlensing exoplanet survey will provide a statistical census of exoplanets with masses down to 0.1 Earth-masses and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by... |
Astrop | USco1606-1935: An Unusually Wide Low-Mass Triple System? | We present photometric, astrometric, and spectroscopic observations of USco160611.9-193532 AB, a candidate ultrawide (~1600 AU), low-mass (M_tot~0.4 M_sun) multiple system in the nearby OB association Upper Scorpius. We conclude that both components are young, comoving members of the association; we also present high-r... |
Astrop | Rotation Measures of Extragalactic Sources Behind the Southern Galactic Plane: New Insights into the Large-Scale Magnetic Field of the Inner Milky Way | We present new Faraday rotation measures (RMs) for 148 extragalactic radio sources behind the southern Galactic plane (253o < l < 356o, |b| < 1.5o), and use these data in combination with published data to probe the large-scale structure of the Milky Way's magnetic field. We show that the magnitudes of these RMs oscill... |
Astrop | The Kilodegree Extremely Little Telescope (KELT): A Small Robotic Telescope for Large-Area Synoptic Surveys | The Kilodegree Extremely Little Telescope (KELT) project is a survey for planetary transits of bright stars. It consists of a small-aperture, wide-field automated telescope located at Winer Observatory near Sonoita, Arizona. The telescope surveys a set of 26 x 26 degree fields, together covering about 25% of the Northe... |
Astrop | Extended solar emission - an analysis of the EGRET data | The Sun was recently predicted to be an extended source of gamma-ray emission, produced by inverse-Compton scattering of cosmic-ray electrons with the solar radiation. The emission was predicted to contribute to the diffuse extragalactic background even at large angular distances from the Sun. While this emission is ex... |
Astrop | Mass and Temperature of the TWA 7 Debris Disk | We present photometric detections of dust emission at 850 and 450 micron around the pre-main sequence M1 dwarf TWA 7 using the SCUBA camera on the James Clerk Maxwell Telescope. These data confirm the presence of a cold dust disk around TWA 7, a member of the TW Hydrae Association. Based on the 850 micron flux, we esti... |
Astrop | Modeling Accretion Disk X-ray Continuum of Black Hole Candidates | We critically examine issues associated with determining the fundamental properties of the black hole and the surrounding accretion disk in an X-ray binary based on modeling the disk X-ray continuum of the source. We base our work mainly on two XMM-Newton observations of GX 339-4, because they provided high-quality dat... |
Astrop | Testing turbulence model at metric scales with mid-infrared VISIR images at the VLT | We probe turbulence structure from centimetric to metric scales by simultaneous imagery at mid-infrared and visible wavelengths at the VLT telescope and show that it departs significantly from the commonly used Kolmogorov model. The data can be fitted by the von Karman model with an outer scale of the order of 30 m and... |
Astrop | Possible non-thermal nature of the soft-excess emission in the cluster of galaxies Sersic 159-03 | We present an analysis of new Suzaku data and archival data from XMM-Newton of the cluster of galaxies Sersic 159-03, which has a strong soft X-ray excess emission component. The Suzaku observation confirms the presence of the soft excess emission, but it does not confirm the presence of redshifted OVII lines in the cl... |
Astrop | The Transition from the First Stars to the Second Stars in the Early Universe | We observe a sharp transition from a singular, high-mass mode of star formation, to a low-mass dominated mode, in numerical simulations, at a metallicity of 10^-3 Zsolar. We incorporate a new method for including the radiative cooling from metals into adaptive mesh-refinement hydrodynamic simulations. Our results illus... |
Astrop | Super Star Cluster Velocity Dispersions and Virial Masses in the M82 Nuclear Starburst | We use high-resolution near-infrared spectroscopy from Keck Observatory to measure the stellar velocity dispersions of 19 super star clusters (SSCs) in the nuclear starburst of M82. The clusters have ages on the order of 10 Myr, which is many times longer than the crossing times implied by their velocity dispersions an... |
Astrop | Kinematic Decoupling of Globular Clusters with Extended Horizontal-Branch | About 25% of the Milky Way globular clusters (GCs) exhibit unusually extended color distribution of stars in the horizontal-branch (HB) phase. This phenomenon is now best understood as due to the presence of helium enhanced second generation subpopulations, which has raised a possibility that these peculiar GCs might h... |
Astrop | Long Distance Signaling Using Axion-like Particles | The possible existence of axion-like particles could lead to a new type of long distance communication. In this work, basic antenna concepts are defined and a Friis-like equation is derived to facilitate long-distance link calculations. An example calculation is presented showing that communication over distances of 10... |
Astrop | Axino warm dark matter and $\Omega_b - \Omega_{DM}$ coincidence | We show that axinos, which are dominantly generated by the decay of the next-to-lightest supersymmetric particles produced from the leptonic $Q$-ball ($L$-ball), become warm dark matter suitable for the solution of the missing satellite problem and the cusp problem. In addition, $\Omega_b - \Omega_{DM}$ coincidence is ... |
Astrop | SDSS J233325.92+152222.1 and the evolution of intermediate polars | Intermediate polars (IPs) are cataclysmic variables which contain magnetic white dwarfs with a rotational period shorter than the binary orbital period. Evolutionary theory predicts that IPs with long orbital periods evolve through the 2-3 hour period gap, but it is very uncertain what the properties of the resulting o... |
Astrop | Dust and gas emission in the prototypical hot core G29.96-0.02 at sub-arcsecond resolution | Aiming at a better understand of the physical and chemical processes in the hot molecular core stage of high-mass star formation, we observed the prototypical hot core G29.96-0.02 in the 862mu band with the Submillimeter Array (SMA) at sub-arcsecond spatial resolution. The observations resolved the hot molecular core i... |
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The training data released in Relay-Assisted Personalized Federated Low-Rank Adaptation over Multi-Cluster Networks.
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