87 research outputs found
RW Doradus: A solar-type shallow contact binary with a new orbital period investigation
New CCD photometric light curves of the short-period (P = 0.285 d) eclipsing binary RW Dor are presented. The observations were performed with the PROMPT-8 robotic telescope at CTIO in Chile between 2015 March and 2017 March. Other eclipse timings were obtained from the 2.15 m JS telescope at CASLEO, San Juan, Argentina in 2011 December. Based on a light curve analysis, it is found that RW Dor is a W-type shallow contact binary with a fill-out factor f ⌠11% and a high mass ratio q ⌠1.587 (1/q = 0.63), where the hotter component is the less massive one (M1 ⌠0.52 M and M2 ⌠0.82 M). For orbital-period investigation, 15 new eclipse times and those previously published were compiled. O â C analysis with very weak evidence suggests that a long-term decrease in period with a rate of dP/dt = â9.61 Ă 10â9 d yrâ1 is superimposed on a cyclic variation(A3 = 0.0054 d and P3 = 49.9 yr). The long-term decrease can be interpreted as mass transfer from the more massive component to the less massive one, or combined with angular momentum loss via magnetic braking. In addition, the marginal contact phase, high mass ratio (1/q > 0.4), and long-term decrease in period all suggest that RW Dor is a newly formed contact binary via Case A mass transfer, and it will evolve into a deepernormal contact binary. If the cyclic change is correct, the light travel-time effect via the presence of a cool third body will be a more plausible explanation for this.Fil: Sarotsakulchai, Thawicharat. University of Chinese Academy of Sciences; China. National Astronomical Research Institute of Thailand; Tailandia. Chinese Academy of Sciences; RepĂșblica de ChinaFil: Qian, Sheng Bang. Chinese Academy of Sciences; RepĂșblica de China. University of Chinese Academy of Sciences; ChinaFil: Soonthornthum, Boonrucksar. National Astronomical Research Institute of Thailand; TailandiaFil: Fernandez Lajus, Eduardo Eusebio. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de AstrofĂsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas. Instituto de AstrofĂsica La Plata; ArgentinaFil: Liu, Nian Ping. Chinese Academy of Sciences; RepĂșblica de ChinaFil: Zhou, Xiao. Chinese Academy of Sciences; RepĂșblica de ChinaFil: Zhang, Jia. Chinese Academy of Sciences; RepĂșblica de ChinaFil: Liao, Wen Ping. Chinese Academy of Sciences; RepĂșblica de ChinaFil: Reichart, Daniel E.. University of North Carolina; Estados UnidosFil: Haislip, Joshua B.. University of North Carolina; Estados UnidosFil: Kouprianov, Vladimir V.. University of North Carolina; Estados UnidosFil: Poshyachinda, Saran. National Astronomical Research Institute of Thailand; Tailandi
RW Doradus: a solar-type shallow contact binary with a new orbital period investigation
New CCD photometric light curves of the short-period (P = 0.285 d) eclipsing binary RW Dor are presented. The observations were performed with the PROMPT-8 robotic telescope at CTIO in Chile between 2015 March and 2017 March. Other eclipse timings were obtained from the 2.15 m JS telescope at CASLEO, San Juan, Argentina in 2011 December. Based on a light curve analysis, it is found that RW Dor is a W-type shallow contact binary with a fill-out factor f ⌠11% and a high mass ratio q ⌠1.587 (1/q = 0.63), where the hotter component is the less massive one (Mâ ⌠0.52 Mâ and Mâ ⌠0.82 Mâ). For orbital-period investigation, 15 new eclipse times and those previously published were compiled. O â C analysis with very weak evidence suggests that a long-term decrease in period with a rate of dP/dt = â9.61 Ă 10â»âč d yrâ»Âč is superimposed on a cyclic variation (Aâ = 0.0054 d and Pâ = 49.9 yr). The long-term decrease can be interpreted as mass transfer from the more massive component to the less massive one, or combined with angular momentum loss via magnetic braking. In addition, the marginal contact phase, high mass ratio (1/q >0.4), and long-term decrease in period all suggest that RW Dor is a newly formed contact binary via Case A mass transfer, and it will evolve into a deeper normal contact binary. If the cyclic change is correct, the light travel-time effect via the presence of a cool third body will be a more plausible explanation for thisInstituto de AstrofĂsica de La Plat
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
Detection of the Diffuse Supernova Neutrino Background with JUNO
As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
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