56 research outputs found
Identification of the Infrared Counterpart to a Newly Discovered X-ray Source in the Galactic Center
We present first results of a campaign to find and identify new compact
objects in the Galactic Center. Selecting candidates from a combination of
Chandra and 2MASS survey data, we search for accretion disk signatures via
infrared spectroscopy. We have found the infrared counterpart to the Chandra
source CXO J174536.1-285638, the spectrum of which has strong Br-gamma and HeI
emission. The presence of CIII, NIII, and HeII indicate a binary system. We
suspect that the system is some form of high-mass binary system, either a
high-mass X-ray binary or a colliding wind binary.Comment: 11 pages, 6 figures, ApJ accepted, 200
High-Resolution Chandra X-Ray Imaging And Spectroscopy Of The Sigma Orionis Cluster
We present results of a 90 ks Chandra X-ray observation of the young sigma Orionis cluster ( age similar to 3 Myr) obtained with the HETGS. We use the high-resolution grating spectrum and moderate-resolution CCD spectrum of the massive central star sigma Ori AB (O9.5 V + B0.5 V) to test wind shock theories of X-ray emission and also analyze the high spatial resolution zero-order ACIS-S image of the central cluster region. Chandra detected 42 X-ray sources on the primary CCD (ACIS-S3). All but five have near-IR or optical counterparts and about one-fourth are variable. Notable high-mass stellar detections are sigma Ori AB, the magnetic B star sigma Ori E, and the B5 V binary HD 37525. Most of the other detections have properties consistent with lower mass K- or M-type stars. We present the first X-ray spectrum of the unusual infrared source IRS 1, located approximate to 3 \u27\u27 north of sigma Ori AB. Its X-ray properties and elongated mid-IR morphology suggest that it is an embedded low-mass T Tauri star whose disk/envelope is being photoevaporated by sigma Ori AB. We focus on the radiative wind shock interpretation of the soft luminous X-ray emission from sigma Ori AB, but also consider possible alternatives including magnetically confined wind shocks and colliding wind shocks. Its emission lines show no significant asymmetries or centroid shifts and are moderately broadened to HWHM approximate to 264 km s(-1), or one-fourth the terminal wind speed. Forbidden lines in He-like ions are formally undetected, implying strong UV suppression. The Mg XI triplet forms in the wind acceleration zone within one stellar radius above the surface. These X-ray properties are consistent in several respects with the predictions of radiative wind shock theory for an optically thin wind, but explaining the narrow line widths presents a challenge to the theory
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A genome-wide association study of Hodgkin Lymphoma identifies new susceptibility loci at 2p16.1 (REL), 8q24.21, and 10p14 (GATA3)
To identify predisposition loci for classical Hodgkin Lymphoma (cHL) we conducted a genome-wide association study of 589 cHL cases and 5,199 controls with validation in 4 independent samples totaling 2,057 cases and 3,416 controls. We identified three new susceptibility loci at 2p16.1 (rs1432295, REL; odds ratio [OR]=1.22, Pcombined=1.91Ă10â8), 8q24.21 (rs2019960, PVT1; OR=1.33, Pcombined=1.26Ă10â13) and 10p14 (rs501764, GATA3; OR=1.25, Pcombined=7.05Ă10â8). Furthermore, we confirmed the role of the MHC in disease etiology by revealing a strong HLA association (rs6903608; OR=1.70, Pcombined=2.84Ă10â50). These data provide new insight into the pathogenesis of cHL
A high-precision near-infrared survey for radial velocity variable low-mass stars using CSHELL and a methane gas cell
We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (â25-150 Myr) moving groups, the young field star Ï” Eridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s-1with a long-term stability of 15-50 m s-1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as âŒ25-50 m s-1 at â2.3125 ÎŒm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ 876 bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD 160934 AB and GJ 725 AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3Ï-5Ï. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of âČ5 m s-1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs
Cattle genome-wide analysis reveals genetic signatures in trypanotolerant N'Dama
Abstract Background Indigenous cattle in Africa have adapted to various local environments to acquire superior phenotypes that enhance their survival under harsh conditions. While many studies investigated the adaptation of overall African cattle, genetic characteristics of each breed have been poorly studied. Results We performed the comparative genome-wide analysis to assess evidence for subspeciation within species at the genetic level in trypanotolerant NâDama cattle. We analysed genetic variation patterns in NâDama from the genomes of 101 cattle breeds including 48 samples of five indigenous African cattle breeds and 53 samples of various commercial breeds. Analysis of SNP variances between cattle breeds using wMI, XP-CLR, and XP-EHH detected genes containing NâDama-specific genetic variants and their potential associations. Functional annotation analysis revealed that these genes are associated with ossification, neurological and immune system. Particularly, the genes involved in bone formation indicate that local adaptation of NâDama may engage in skeletal growth as well as immune systems. Conclusions Our results imply that NâDama might have acquired distinct genotypes associated with growth and regulation of regional diseases including trypanosomiasis. Moreover, this study offers significant insights into identifying genetic signatures for natural and artificial selection of diverse African cattle breeds
Decision-Making Guide for Bee Supplementation of Pumpkin Fields
NYS IPM Type: Vegetables IPM Fact SheetVine crops such as pumpkin, squash, cucumber and watermelon are some of New York Stateâs most valuable vegetable crops. These crops require pollination by bees, the most well-known of which is the honey bee, Apis mellifera. Honey bee hives are placed in vine crops during bloom when female flowers need to be pollinated. Unfortunately, Colony Collapse Disorder (CCD), parasitic mites, viruses and other pathogens continue to cause significant losses in populations of honey bees throughout the US
Combining Cultivation and Interseeded Cover Crops for Weed Control in Transplanted Cabbage
NYS IPM Type: Project ReportResearch conducted in 1995 and 1996 has shown that cultivation with or without interseeded cover crops can control weeds and maintain yields in transplanted cabbage
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