Oxygen Isotopes of Al-Rich Chondrules from Unequilibrated Ordinary Chondrites

Al-rich chondrules (ARCs) are a rare constituent of chondrites. They have relatively high bulk Al_2O_3 content (> 10 wt%), which is due to the presence of Al-rich phases, such as plagioclase, spinel, Al-rich glass etc. [1]. ARCs share some chemical and petrologic characteristics with Ca, Al-rich inclusions (CAis), and may represent a genetic link between ferromagnesian chondrules and CAis

WZ Sge-Type Star V592 Herculis

We observed the entire course of the 1998 outburst of V592 Her, which was originally reported as a nova in 1968. We have been able to construct a full light curve of the outburst, which is characterized by a rapid initial decline (0.98 mag/d), which smoothly developed into a plateau phase with a slower linear decline. We detected superhumps characteristic to SU UMa-type dwarf novae ~7 d after the optical maximum. The overall behavior of the light curve and the development of superhumps were characteristic to a WZ Sge-type dwarf nova. Combined with the past literature, we have been able to uniquely determine the superhump period to be 0.05648(2) d. From this period, together with a modern interpretation of the absolute magnitude of the outburst light curve, we conclude that the overall picture of V592 Her is not inconsistent with a lower main-sequence secondary star in contrast to a previous claim that V592 Her contains a brown dwarf.Comment: 10 pages, 7 figures, accepted for publication in Publ. Astron. Soc. Japa

Two X-Ray Bright Cataclysmic Variables with Unusual Activities: GZ Cnc and NSV 10934

We report on a discovery of unexpected activities in two X-ray bright dwarf novae. GZ Cnc showed an anomalous clustering of outbursts in 2002, in contrast to a low outburst frequency in the past record. The activity resembles an increased activity seen in some intermediate polars or candidates. We identified NSV 10934, X-ray selected high-amplitude variable star, as a dwarf nova with unusually rapid decline. The outburst characteristics make NSV 10934 a twin of recently discovered intermediate polar (HT Cam) with dwarf nova-type outbursts. We propose that these activities in X-ray strong dwarf novae may be a previously overlooked manifestation of outburst activities in magnetic cataclysmic variables

Lower Neutrino Mass Bound from SN1987A Data and Quantum Geometry

A lower bound on the light neutrino mass $m_\nu$ is derived in the framework of a geometrical interpretation of quantum mechanics. Using this model and the time of flight delay data for neutrinos coming from SN1987A, we find that the neutrino masses are bounded from below by $m_\nu\gtrsim 10^{-4}-10^{-3}$eV, in agreement with the upper bound $m_\nu\lesssim$ $({\cal O}(0.1) - {\cal O} (1))$ eV currently available. When the model is applied to photons with effective mass, we obtain a lower limit on the electron density in intergalactic space that is compatible with recent baryon density measurements.Comment: 22 pages, 3 figure

SN 2008jb: A "Lost" Core-Collapse Supernova in a Star-Forming Dwarf Galaxy at ~10 Mpc

We present the discovery and follow-up observations of SN 2008jb, a core-collapse supernova in the dwarf irregular galaxy ESO 302-14 at 9.6 Mpc. This transient was missed by galaxy-targeted surveys and was only found in archival optical images obtained by CRTS and ASAS. It was detected shortly after explosion and reached a bright optical maximum, Vmax = 13.6 mag (M_Vmax ~ -16.5). The shape of the light curve shows a plateau of 100 days, followed by a drop of 1.4 mag in V-band to a decline with the approximate Co 56 decay slope, consistent with 0.04 Msun of Ni 56 synthesized in the explosion. A spectrum obtained 2 years after explosion shows a broad, boxy Halpha emission line, which is unusual for type IIP supernovae. We detect the supernova in archival Spitzer and WISE images obtained 8-14 months after explosion, which show clear signs of warm dust emission. The dwarf irregular host galaxy has a low gas-phase oxygen abundance, 12 + log(O/H) = 8.2 (~1/5 Solar), similar to those of the SMC and the hosts of long gamma-ray bursts and luminous core-collapse supernovae. We study the host environment using GALEX FUV, R-band, and Halpha images and find that the supernova occurred in a large star-formation complex. The morphology of the Halpha emission appears as a large shell (R = 350 pc) surrounding the FUV and optical emission. We estimate an age of ~9 Myr and a total mass of ~2 x 10^5 Msun for the star-formation complex. These properties are consistent with the expanding Halpha supershells observed in well-studied nearby dwarf galaxies, which are tell-tale signs of feedback from the cumulative effect of massive star winds and supernovae. The age estimated for the star-forming region suggests a relatively high-mass progenitor star with initial mass of ~20 Msun. We discuss the implications of these findings in the study of core-collapse supernova progenitors. (Abridged)Comment: 41 pages, 10 figures, accepted in ApJ; small changes, conclusions unchange

The Early Optical Afterglow of GRB 030418 and Progenitor Mass Loss

The ROTSE-IIIa telescope and the SSO 40 inch (1.0 m) telescope, both located at Siding Spring Observatory, imaged the early-time afterglow of GRB 030418. In this report, we present observations of the early afterglow, first detected by the ROTSE-IIIa telescope 211 s after the start of the burst and only 76 s after the end of the gamma-ray activity. We detect optical emission that rises for ∼600 s, slowly varies around R = 17.3 mag for ∼1400 s, and then fades as a power law of index α = -1.36. Additionally, the ROTSE-IIIb telescope, located at McDonald Observatory, imaged the early-time afterglow of GRB 030723. The behavior of this light curve was qualitatively similar to that of GRB 030418, but 2 mag dimmer. These two afterglows are dissimilar to other afterglows such as GRB 990123 and GRB 021211. We investigate whether or not the early afterglow can be attributed to a synchrotron break in a cooling synchrotron spectrum as it passes through the optical band, but we find that this model is unable to accurately describe the early light curve. We present a simple model for gamma-ray burst emission emerging from a wind medium surrounding a massive progenitor star. This model provides an effective description of the data and suggests that the rise of the afterglow can be ascribed to extinction in the local circumburst environment. In this interpretation, these events provide further evidence of the connection between gamma-ray bursts and the collapse of massive stars.This work has been supported by NASA grants NAG5- 5281 and F006794, NSF grants AST 01-19685 and 01-05221, the Australian Research Council, the University of New South Wales, and the University of Michigan. Work performed at LANL is supported by NASA SR&T through Department of Energy (DOE) contract W-7405-ENG-36 and through internal LDRD funding

The early optical afterglow of GRB 030418 and progenitor mass loss

The ROTSE-IIIa telescope and the SSO 40 inch (1.0 m) telescope, both located at Siding Spring Observatory, imaged the early-time afterglow of GRB 030418. In this report, we present observations of the early afterglow, first detected by the ROTSE-IIIa telescope 211 s after the start of the burst and only 76 s after the end of the gamma-ray activity. We detect optical emission that rises for ∼600 s, slowly varies around R = 17.3 mag for ∼1400 s, and then fades as a power law of index α = -1.36. Additionally, the ROTSE-IIIb telescope, located at McDonald Observatory, imaged the early-time afterglow of GRB 030723. The behavior of this light curve was qualitatively similar to that of GRB 030418, but 2 mag dimmer. These two afterglows are dissimilar to other afterglows such as GRB 990123 and GRB 021211. We investigate whether or not the early afterglow can be attributed to a synchrotron break in a cooling synchrotron spectrum as it passes through the optical band, but we find that this model is unable to accurately describe the early light curve. We present a simple model for gamma-ray burst emission emerging from a wind medium surrounding a massive progenitor star. This model provides an effective description of the data and suggests that the rise of the afterglow can be ascribed to extinction in the local circumburst environment. In this interpretation, these events provide further evidence of the connection between gamma-ray bursts and the collapse of massive stars