Type Ia supernovae (SNe Ia) are more precise standardizable candles when measured in the near-infrared (NIR) than in the optical. With this motivation, from 2012-2017 we embarked on the RAISIN ...program with the Hubble Space Telescope (HST) to obtain rest-frame NIR light curves for a cosmologically distant sample of 37 SN Ia (\(0.2 \lesssim z \lesssim 0.6\)) discovered by Pan-STARRS and the Dark Energy Survey. By comparing higher-\(z\) HST data with 42 SN Ia at \(z<0.1\) observed in the NIR by the Carnegie Supernova Project, we construct a Hubble diagram from NIR observations (with only time of maximum light and some selection cuts from optical data) to pursue a unique avenue to constrain the dark energy equation of state parameter, \(w\). We analyze the dependence of the full set of Hubble residuals on the SN Ia host galaxy mass and find Hubble residual steps of size \(\sim\)0.06-0.1~mag with 1.5- to 2.5-\(\sigma\) significance depending on the method and step location. Combining our NIR sample with CMB constraints, we find \(1+w=-0.17\pm0.12\) (stat\(+\)syst). The largest systematic errors are the redshift-dependent SN selection biases and the properties of the NIR mass step. We also use these data to measure \(H_0=75.9\pm 2.2\) km s\(^{-1}\) Mpc\(^{-1}\) from stars with geometric distance calibration in the hosts of 8 SNe Ia observed in the NIR versus \(H_0=71.2\pm3.8\) km s\(^{-1}\) Mpc\(^{-1}\) using an inverse distance ladder approach tied to Planck. Using optical data we find \(1+w=-0.10\pm0.09\) and with optical and NIR data combined, we find \(1+w=-0.06\pm0.07\); these shifts of up to 0.11 in \(w\) could point to inconsistency in optical versus NIR SN models. There will be many opportunities to improve this NIR measurement and better understand systematic uncertainties through larger low-\(z\) samples, new light-curve models, calibration improvements, and by building high-\(z\) samples from the Roman Space Telescope.
A New Cataclysmic Variable in Hercules Price, A.; Gary, B.; Bedient, J. ...
Publications of the Astronomical Society of the Pacific,
12/2004, Letnik:
116, Številka:
826
Journal Article
Recenzirano
Odprti dostop
We present time‐series observations, spectra, and archival outburst data of a newly discovered variable star in Hercules, Var Her 04. Its orbital period, mass ratio, and outburst amplitude resemble ...those of the ugwz‐type subclass of ugsu dwarf novae. However, its supercycle and outburst light curve defy classification as a clear ugwz. Var Her 04 is most similar to the small group of possible hydrogen‐burning “period bouncers,” dwarf novae that have passed beyond the period minimum and returned.
The JET Trace Tritium (TTE) programme marked the first use of tritium in experiments under the managerial control of UKAEA, which operates the JET Facility on behalf of EFDA. The introduction of ...tritium into the plasma by gas fuelling and neutral beam injection, even in trace quantities, required the mobilisation of gram-quantities of tritium gas from the Active Gas Handling System (AGHS) product storage units into the supply lines connected to the torus gas valve and the neutral beam injectors. All systems for DT gas handling, recovery and reprocessing were therefore recommissioned and operating procedures re-established, involving extensive operations staff training. The validation of Key Safety Related Equipment (KSRE) is described with reference to specific examples. The differences between requirements for TTE and full DT operations are shown to be relatively small. The scientific motivation for TTE, such as the possibility to obtain high-quality measurements in key areas such as fuel-ion transport and fast ion dynamics, is described, and the re-establishment and development of JET's 14MeV neutron diagnostic capability for TTE and future DT campaigns are outlined. Some scientific highlights from the TTE campaign are presented.
We investigate the environment of the nearby (d {approx} 40 Mpc) broad-lined Type Ic supernova (SN) 2009bb. This event was observed to produce a relativistic outflow likely powered by a central ...accreting compact object. While such a phenomenon was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB was detected in association with SN 2009bb. Using an optical spectrum of the SN 2009bb explosion site, we determine a variety of interstellar medium properties for the host environment, including metallicity, young stellar population age, and star formation rate. We compare the SN explosion site properties to observations of LGRB and broad-lined SN Ic host environments on optical emission line ratio diagnostic diagrams. Based on these analyses, we find that the SN 2009bb explosion site has a metallicity between 1.7 Z {sub sun} and 3.5 Z {sub sun}, in agreement with other broad-lined SN Ic host environments and at odds with the low-redshift LGRB host environments and recently proposed maximum metallicity limits for relativistic explosions. We consider the implications of these findings and the impact that SN 2009bb's unusual explosive properties and environment have on our understanding of the key physical ingredient that enables some SNe to produce a relativistic outflow.
The cure of an epichlorohydrin-bisphenol A resin and hardener containing a primary diamine and an amido-polyamine has been studied using two complementary non-invasive techniques. Low resolution ...pulsed nuclear magnetic resonance has been used to track the change from viscous liquid to crosslinked solid as the resin cured by following the free induction decay of magnetically active hydrogen nuclei. The Carr–Purcell–Meiboom–Gill technique resolved two changing components in the liquid phase. It is suggested that the two phases are initially the resin and hardener which subsequentially change into an intermediate alcoholic hydroxyl and secondary amine and finally the crosslinked solid. Pulsed broad bandwidth ultrasound propagation velocity and absorption changes during cure have been related to the change in physical state of the curing resin as it evolves from a viscous liquid to an elastic solid. The two techniques independently give a similar picture of the cure process, predicting cure events at the same times. Results suggest the cure follows distinct phases: an initial liquid stage where short polymer chains are formed followed by a second stage where longer molecules develop, a third stage where crosslinking between chains occurs and the adhesive begins to solidify, and a final stage when solidification completes.
Biochemical studies have shown the presence of type I oxidized nicotinamide-adenine dinucleotide-dependent 15-hydroxyprostaglandin dehydrogenase in human fetal membranes, decidua, and placenta. ...However, the localization of prostaglandin dehydrogenase within these tissues is not known. Because the distribution of prostaglandin dehydrogenase may affect the concentration of prostaglandins that reach the myometrium, we used immunocytochemistry to localize immunoreactive prostaglandin dehydrogenase in fetal membranes and placenta. We also examined whether this distribution changed with labor. Tissues were collected at term elective cesarean section or after term spontaneous labor and delivery, were fixed, embeded, and sectioned at 5 microns. Immunoreactive prostaglandin dehydrogenase was determined with a polyclonal primary antibody to human placental prostaglandin dehydrogenase and visualized with the avidin-biotin procedure. Epithelial and epithelium-derived cells were identified by positive staining with a polyclonal antikeratin primary antibody. Cytokeratin staining was observed in amniotic epithelium, trophoblast layer of chorion, invading trophoblast in decidua, and all subsets of trophoblast in the placenta. Immunoreactive prostaglandin dehydrogenase was localized to the trophoblast layer of chorion, invading trophoblast in decidua, and in syncytiotrophoblast and intermediate trophoblast but not cytotrophoblast in the placenta. In chorion, approximately 50% to 60% of the nonvacuolated trophoblast cells stained positively for prostaglandin dehydrogenase. There was no change in the localization of immunoreactive prostaglandin dehydrogenase in any tissue in association with labor.
A possible low-mass type Ia supernova Ruiz-Lapuente, Pilar; Jeffery, David J; Challis, Peter M ...
Nature (London),
10/1993, Letnik:
365, Številka:
6448
Journal Article
Recenzirano
Evidence from the supernova SN1991bg challenges the double white-dwarf scenario and the model for type Ia supernovae. Calculations on the spectra of the supernova are offered.
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