15000344
Starspot-Induced Radial Velocity Variability in LkCa 19
We describe a new radial velocity survey of T Tauri stars and present the first results. Our search is motivated by an interest in detecting massive young planets, as well as investigating the origin of the brown dwarf desert. As part of this survey, we discovered large-amplitude, periodic, radial velocity variations in the spectrum of the weak-line T Tauri star LkCa 19. Using line bisector analysis and a new simulation of the effect of starspots on the photometric and radial velocity variability of T Tauri stars, we show that our measured radial velocities for LkCa 19 are fully consistent with variations caused by the presence of large starspots on this rapidly rotating young star. These results illustrate the level of activity-induced radial velocity noise associated with at least some very young stars. This activity-induced noise will set lower limits on the mass of a companion detectable around LkCa 19 and similarly active young stars.
122125252
The TEXES Survey For H-2 Emission From Protoplanetary Disks
16613665
NEAR-INFRARED MOLECULAR HYDROGEN EMISSION FROM THE CENTRAL REGIONS OF GALAXIES: REGULATED PHYSICAL CONDITIONS IN THE INTERSTELLAR MEDIUM
The central regions of many interacting and early-type spiral galaxies are actively forming stars. This process affects the physical and chemical properties of the local interstellar medium, as well as the evolution of the galaxies. We observed near-infrared H2 emission lines: v ¼ 1 0 S(1), 3–2 S(3), 1–0 S(0), and 2–1 S(1) from the central � 1 kpc regions of the archetypical starburst galaxies M82 and NGC 253 and the less dramatic but still vigorously star-forming galaxies NGC 6946 and IC 342. Like the far-infrared continuum luminosity, the nearinfrared H2 emission luminosity can directly trace the amount of star formation activity because the H2 emission lines arise from the interaction between hot and young stars and nearby neutral clouds. The observed H2 line ratios show that both thermal excitation and nonthermal excitation are responsible for the emission lines but that the great majority of the near-infrared H2 line emission in these galaxies arises from energy states excited by ultraviolet fluorescence. The derived physical conditions, e.g., far-ultraviolet radiation field and gas density, from [C ii ]a nd [O i] lines and far-infrared continuum observations when used as inputs to photodissociation models also explain the luminosity of the observed H2 1–0S(1) line. The ratio of the H2 1–0S(1) line to far-IR continuum luminosity is remarkably constant over a broad range of galaxy luminosities: LH2 =LFIR ’ 10 � 5 , in normal late-type galaxies (including the Galactic center), in nearby starburst galaxies, and in luminous IR galaxies (LIRGs: LFIR >10 11 L� ). Examining this constant ratio in the context of photodissociation region models, we conclude that it implies that the strength of the incident UV field on typical molecular clouds follows the gas density at the cloud surface. Subject headings: galaxies: individual(M82,NGC 253,NGC6946,IC 342) — galaxies: ISM — galaxies:spiral — galaxies: starburst — infrared: ISM — ISM: lines and bands
15532404
Molecular cloud structure in the magellanic clouds: Effect of metallicity
The chemical structure of neutral clouds in low-metallicity environments is examined, with particular emphasis on the H to H2 and C+ to CO transitions. We observed near-IR H2 (1, 0) S(1), (2, 1) S(1), and (5, 3) O(3) lines and the 12CO J = 1 → 0 line from 30 Doradus and N159/N160 in the Large Magellanic Cloud and from DEM S 16, DEM S 37, and LI-SMC 36 in the Small Magellanic Cloud. We find that the H2 emission is UV-excited and that (weak) CO emission always exists (in our surveyed regions) toward positions where H2 and [C II] emission have been detected. Using a PDR code and a radiative transfer code, we simulate the emission of line radiation from spherical clouds and from large planar clouds. Because [C II] emission and H2 emission arise on the surface of the cloud and because the lines are optically thin, these lines are not affected by changes in the relative sizes of the neutral cloud and the CO-bearing core, while the optically thick CO emission can be strongly affected. The sizes of clouds are estimated by measuring the deviation of CO emission strength from that predicted by a planar cloud model of a given size. The average cloud column density, and therefore its size, increases as the metallicity decreases. Our result agrees with the photoionization-regulated star formation theory of McKee.
16861138
High Sensitivity, High Spectral Resolution, Mid-infrared Spectroscopy
We broadly discuss mid-infrared spectroscopy and detail our new high spectral resolution instrument, the Texas Echelon-cross-Echelle Spectrograph (TEXES).
209907524
Photon - dominated regions in low UV fields : a study of the peripheral regions of L1204 /S140
118745241
Status of Neutrino Physics Experiments
Relevant results from neutrino physics experiments since FPCP2009 with an emphasis on oscillations and the ability to measure or limit the mixing angle {theta}{sub 13}.
14433479
Search for CP violation at CLEO
Abstract Recent results from CLEO on the search for CP violation in beauty and charm meson decays are reviewed.
29707171
Design and performance of beam test electronics for the PHENIX Multiplicity Vertex Detector
The system architecture and test results of the custom circuits and beam test system for the Multiplicity-Vertex Detector (MVD) for the PHENIX detector collaboration at the Relativistic Heavy Ion Collider (RHIC) are presented in this paper. The final detector per-channel signal processing chain will consist of a preamplifier-gain stage, a current-mode summed multiplicity discriminator, a 64-deep analog memory (simultaneous read-write), a post-memory analog correlator, and a 10-bit 5 /spl mu/s ADC. The Heap Manager provides all timing control, data buffering, and data formatting for a single 256-channel multi-chip module (MCM). Each chip set is partitioned into 32-channel sets. Beam test (16-cell deep memory) performance for the various blocks will be presented as well as the ionizing radiation damage performance of the 1.2 /spl mu/ n-well CMOS process used for preamplifier fabrication.
124863739
The PHENIX Multiplicity and Vertex Detector
Abstract We describe the design and expected performance of the PHENIX Multiplicity and Vertex Detector (MVD) sub-system of the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC).
119540499
Low cost lead glass cherenkov detectors
Abstract We have compared the optical properties of lead glass bars of three different surface qualities. One was ground and polished in the conventional manner; the other two were in the unimproved state resulting from the extrusion or casting process. We find that the three bars exhibit similar optical characteristics. Use of such unpolished lead glass Cherenkov bars in electromagnetic shower detectors should result in considerable cost savings.