On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40 − 8 + 8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 M ⊙ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 Mpc ) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.
Ventricular pressure-volume relationships have become well established as the most rigorous and comprehensive ways to assess intact heart function. Thanks to advances in miniature sensor technology, this approach has been successfully translated to small rodents, allowing for detailed characterization of cardiovascular function in genetically engineered mice, testing effects of pharmacotherapies and studying disease conditions. This method is unique for providing measures of left ventricular (LV) performance that are more specific to the heart and less affected by vascular loading conditions. Here we present descriptions and movies for procedures employing this method (anesthesia, intubation and surgical techniques, calibrations). We also provide examples of hemodynamics measurements obtained from normal mice/rats, and from animals with cardiac hypertrophy/heart failure, and describe values for various useful load-dependent and loadindependent indexes of LV function obtained using different types of anesthesia. The completion of the protocol takes 1-4 h (depending on the experimental design/end points).
We present the discovery of a Neptune-mass planet OGLE-2007-BLG-368Lb with a planet-star mass ratio of q = [9.5 ± 2.1] × 10 −5 via gravitational microlensing. The planetary deviation was detected in real-time thanks to the high cadence of the Microlensing Observations in Astrophysics survey, real-time light-curve monitoring and intensive follow-up observations. A Bayesian analysis returns the stellar mass and distance at M l = 0.64 +0.21 −0.26 M and D l = 5.9 +0.9 −1.4 kpc, respectively, so the mass and separation of the planet are M p = 20 +7 −8 M ⊕ and a = 3.3 +1.4 −0.8 AU, respectively. This discovery adds another cold Neptune-mass planet to the planetary sample discovered by microlensing, which now comprises four cold Neptune/super-Earths, five gas giant planets, and another sub-Saturn mass planet whose nature is unclear. The discovery of these 10 cold exoplanets by the microlensing method implies that the mass ratio function of cold exoplanets scales as dN pl /d log q ∝ q −0.7±0.2 with a 95% confidence level upper limit of n < −0.35 (where dN pl /d log q ∝ q n). As microlensing is most sensitive to planets beyond the snow-line, this implies that Neptune-mass planets are at least three times more common than Jupiters in this region at the 95% confidence level.
-On the basis of near-infrared imaging observations, we derived visual extinction (A V ) distribution toward ten Bok globules through measurements of both the color excess (E H−K ) and the stellar density at J, H, and K s (star count). Radial column density profiles for each globule were analyzed with the Bonnor-Ebert sphere model. Using the data of our ten globules and four globules in the literature, we investigated the stability of globules on the basis of ξ max , which characterizes the Bonnor-Ebert sphere as well as the stability of the equilibrium state against the gravitational collapse. We found that more than half of starless globules are located near the critical state (ξ max = 6.5 ± 2). Thus, we suggest that a nearly critical Bonnor-Ebert sphere characterizes the typical density structure of starless globules. Remaining starless globules show clearly unstable states (ξ max > 10). Since unstable equilibrium states are not long maintained, we expect that these globules are on the way to gravitational collapse or that they are stabilized by non-thermal support. It was also found that all the starforming globules show unstable solutions of ξ max > 10, which is consistent with the fact that they have started gravitational collapse. We investigated the evolution of a collapsing gas sphere whose initial condition is a nearly critical Bonnor-Ebert sphere. We found that the column density profiles of the collapsing sphere mimic those of the static Bonnor-Ebert spheres in unstable equilibrium. The collapsing gas sphere resembles marginally unstable Bonnor-Ebert spheres for a long time. We found that the frequency distribution of ξ max for the observed starless globules is consistent with that from model calculations of the collapsing sphere. In addition to the near-infrared observations, we carried out radio molecular line observations (C 18 O and N 2 H + ) toward the same ten globules. We confirmed that most of the globules are dominated by thermal support. The line width of each globule was used to estimate the cloud temperature including the contribution from turbulence, with which we estimated the distance to the globules from the Bonnor-Ebert model fitting.Subject headings: ISM: clouds -dust, extinction -ISM: globules -stars: formation * Recently, a low luminosity protostar was discovered toward the globule Lynds 1014, which is known to accompany no IRAS point sources, using the Spitzer Space Telescope (Young et al. 2004). Though Spitzer data are useful to clarify whether globules contain protostars or not, Spitzer data is available only for one source, CB 131, among the "IRAS-less" globules in Table 1. We briefly checked mid-infrared data of the Spitzer telescope toward CB 131 and found that there is no protostar candidates near the center of the globule. Though a source is located near the globule †
We have performed a cross-identification between Optical Gravitational Lensing Experiment II (OGLE-II) data and single-epoch Simultaneous three-colour Infrared Imager for Unbiased Surveys (SIRIUS) near-infrared (NIR) JHK survey data in the Large and Small Magellanic Clouds (LMC and SMC, respectively). After eliminating obvious spurious variables, variables with too few good data and variables that seem to have periods longer than the available baseline of the OGLE-II data, we determined the pulsation periods for 8852 and 2927 variables in the LMC and SMC, respectively.Based on these homogeneous data, we studied the pulsation properties and metallicity effects on period-K magnitude (PK) relations by comparing the variable stars in the LMC and SMC. The sample analysed here is much larger than the previous studies, and we found the following new features in the PK diagram. (1) Variable red giants in the SMC form parallel sequences on the PK plane, just like those found by Wood in the LMC. (2) Both sequences A and B of Wood have discontinuities, and they occur at the K-band luminosity of the tip of the red giant branch. (3) The sequence B of Wood separates into three independent sequences B ± and C . (4) A comparison between the theoretical pulsation models and observational data suggests that the variable red giants on sequences C and newly discovered C are pulsating in the fundamental and first overtone modes, respectively. (5) The theory cannot explain the pulsation mode of sequences A ± and B ± , and they are unlikely to be the sequences for the first and second overtone pulsators, as was previously suggested. (6) The zero-points of PK relations of Cepheids in the metal deficient SMC are fainter than those of the LMC by ≈0.1 mag but those of SMC Miras are brighter than those of the LMC by ≈0.13 mag (adopting the distance modulus offset between the LMC and SMC to be 0.49 mag and assuming the slopes of the PK relations are the same in the two galaxies), which are probably due to metallicity effects.
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