Unraveling the Infrared Transient VVV-WIT-06: The Case for the Origin as a Classical Nova

Indexación: Scopus.E.Y.H. acknowledges the support provided by the National Science Foundation under Grant No. AST-1613472 and by the Florida Space Grant Consortium. L.G. acknowledges support from the FINCA visitor programme. The research work at the Physical Research Laboratory is funded by the Department of Space, Government of India. Facility: Magellan: Baade(FIRE).The enigmatic near-infrared transient VVV-WIT-06 underwent a large-amplitude eruption of unclear origin in 2013 July. Based on its light curve properties and late-time post-outburst spectra, various possibilities have been proposed in the literature for the origin of the object, namely a Type I supernova, a classical nova (CN), or a violent stellar merger event. We show that, of these possibilities, an origin in a CN outburst convincingly explains the observed properties of VVV-WIT-06. We estimate that the absolute K-band magnitude of the nova at maximum was M k = -8.2 ±0.5, its distance d = 13.35 ±2.18 kpc, and the extinction A v = 15.0 ±0.55 mag. © 2018. The American Astronomical Society. All rights reserved.https://iopscience.iop.org/article/10.3847/1538-4357/aae5d

The Addition of Arachidin 1 or Arachidin 3 to Human Rotavirus-infected Cells Inhibits Viral Replication and Alters the Apoptotic Cell Death Pathway

Rotavirus (RV) infections are a leading cause of severe gastroenteritis in infants and children under the age of five. There are two vaccines available in the United States and one in India that can be administered early in childhood, however they only protect against specific strains1. From our previous work, both arachidin-1 (A1) and arachidin-3 (A3) from peanut (Arachis hypogaea) hairy root cultures significantly inhibit simian RV replication2,3,4. The purpose of this study was to determine if a human intestinal cell line, HT29.f8, infected with a human RV, Wa, was affected by A1 and A3. Cell viability assays were utilized to determine if A1 and A3 affect the HT29.f8 cells with/without RV infections. At eighteen hours post infection (hpi), supernatants from the RV-infected HT29.f8 cells with/without the arachidins were used in plaque forming assays to quantify and compare the amount of infectious RV particles that are produced during an infection. Transmission electron microscopy (TEM) was used to visualize cell ultrastructure and individual RV particles. Additionally, tunable resistive pulse sensing technology (TRPS) using the qNano system by IZON was employed to quantify and measure virus particle sizes, and display the size distribution of RV particles. Likewise, quantitative real time polymerase chain reactions (qRT-PCR) were performed to determine if A1 and A3 regulated cell death pathways in the HT29.f8 cell line. This data will guide our future studies to determine the antiviral mechanism(s) of action of A1 and A3

The envelope of IRC+10216 reflecting the galactic light: UBV surface brightness photometry and interpretation

We present and analyse new optical images of the dust envelope surrounding the high mass-loss carbon star IRC+10216. This envelope is seen due to external illumination by galactic light. Intensity profiles and colors of the nebula were obtained in the UBV bandpasses. The data are compared with the results of a radiative transfer model calculating multiple scattering of interstellar field photons by dust grains with a single radius. The data show that the observed radial shape of the nebula, especially its half maximum radius, does not depend on wavelength (within experimental errors), suggesting that grains scatter in the grey regime, etc, etc (this abstract has been shortened)Comment: accepted by A

Cosmic Optical Background: the View from Pioneer 10/11

We present the new constraints on the cosmic optical background (COB) obtained from an analysis of the Pioneer 10/11 Imaging Photopolarimeter (IPP) data. After careful examination of data quality, the usable measurements free from the zodiacal light are integrated into sky maps at the blue (~0.44 um) and red (~0.64 um) bands. Accurate starlight subtraction is achieved by referring to all-sky star catalogs and a Galactic stellar population synthesis model down to 32.0 mag. We find that the residual light is separated into two components: one component shows a clear correlation with thermal 100 um brightness, while another betrays a constant level in the lowest 100 um brightness region. Presence of the second component is significant after all the uncertainties and possible residual light in the Galaxy are taken into account, thus it most likely has the extragalactic origin (i.e., the COB). The derived COB brightness is (1.8 +/- 0.9) x 10^(-9) and (1.2 +/- 0.9) x 10^(-9) erg/s/cm2/sr/A at the blue and red band, respectively, or 7.9 +/- 4.0 and 7.7 +/- 5.8 nW/m2/sr. Based on a comparison with the integrated brightness of galaxies, we conclude that the bulk of the COB is comprised of normal galaxies which have already been resolved by the current deepest observations. There seems to be little room for contributions of other populations including "first stars" at these wavelengths. On the other hand, the first component of the IPP residual light represents the diffuse Galactic light (DGL) - scattered starlight by the interstellar dust. We derive the mean DGL-to-100 um brightness ratios of 2.1 x 10^(-3) and 4.6 x 10^(-3) at the two bands, which are roughly consistent with the previous observations toward denser dust regions. Extended red emission in the diffuse interstellar medium is also confirmed.Comment: Accepted for publication in the Astrophysical Journal; Typos correcte

Radio monitoring of NGC 7469: Late time radio evolution of SN 2000ft and the circumnuclear starburst in NGC 7469

We present the results of an eight-year long monitoring of the radio emission from the Luminous Infrared Galaxy (LIRG) NGC 7469, using 8.4 GHz Very Large Array (VLA) observations at 0.3'' resolution. Our monitoring shows that the late time evolution of the radio supernova SN 2000ft follows a decline very similar to that displayed at earlier times of its optically thin phase. The late time radio emission of SN 2000ft is therefore still being powered by its interaction with the presupernova stellar wind, and not with the interstellar medium (ISM). Indeed, the ram pressure of the presupernova wind is \rho_w v_w^2 \approx 7.6E-9 dyn/cm^2, at a supernova age of approximately 2127 days, which is significantly larger than the expected pressure of the ISM around SN 2000ft. At this age, the SN shock has reached a distance r_{sh \approx 0.06 pc, and our observations are probing the interaction of the SN with dense material that was ejected by the presupernova star about 5820 years prior to its explosion. From our VLA monitoring, we estimate that the swept-up mass by the supernova shock after about six years of expansion is \approx 0.29 M_sun, assuming an average expansion speed of the supernova of 10000 km/s. We also searched for recently exploded core-collapse supernovae in our VLA images. Apart from SN 2000ft (S_\nu \approx 1760 microJy at its peak, corresponding to 1.1E28 erg/s/Hz, we found no evidence for any other radio supernova (RSN) more luminous than \approx 6.0E26 erg/s/Hz, which suggests that no other Type IIn SN has exploded since 2000 in the circumnuclear starburst of NGC 7469.Comment: 10 pages, 5 figures, accepted for publication in MNRA

Temperature and pressure-induced spin-state transitions in LaCoO3

We report the continuous variation of the spin moment of cobalt in LaCoO3 across its temperature and pressure-induced spin transitions evidenced with K\beta emission spectra. The first thermal transition is best described by a transition to an orbitally nondegenerate intermediate spin (S=1) state. In parallel, continuous redistribution of the 3d electrons is also indicated by partial fluorescence yield X-ray absorption spectra. At high pressure, our study confirms that the material becomes low spin between 40 and 70 kbar at room temperature

On the Origins of the High-Latitude H-alpha Background

The diffuse high-latitude H-alpha background is widely believed to be predominantly the result of in-situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of the diffuse high-latitude H-alpha intensity in regions dominated by Galactic cirrus dust and much of the variance in the high-latitude H-alpha background are the result of scattering by interstellar dust of H-alpha photons originating elsewhere in the Galaxy. We provide an empirical relation, which relates the expected scattered H-alpha intensity to the IRAS 100um diffuse background intensity, applicable to about 81% of the entire sky. The assumption commonly made in reductions of CMB observations, namely that the observed all-sky map of diffuse H-alpha light is a suitable template for Galactic free-free foreground emission, is found to be in need of reexamination.Comment: 26 pages, 5 figures, Accepted for publication in Ap

Levels of the cancer biomarker CA 19-9 are associated with thrombin generation in plasma from treatment-na?ve pancreatic cancer patients

Background: Pancreatic ductal adenocarcinoma (PDAC) is associated with a hypercoagulable state and high mortality. Increases in the plasma levels of tumor marker carbohydrate antigen (CA) 19-9 are used in diagnosis and follow-up but have also been reported to precede venous thromboembolism (VTE). Aims: We examined the association between CA 19-9 and thrombin generation (TG) in plasma from PDAC patients, as well as their association with coagulation biomarkers prior to pancreatic surgery. In addition, we determined the effect of commercial sources of CA 19-9 on TG. Methods: We collected plasma from 58 treatment-naive PDAC patients without any signs of VTE. We measured levels of CA 19-9, FVIII, fibrinogen, D-dimer, antithrombin and extracellular vesicle (EV) tissue factor (TF) activity and TG using a Calibrated Automated Thrombogram (CAT). The effect of different commercial sources of CA 19-9 on TG in Standard Human Plasma (SHP) was also studied. Results: Patient plasma samples were divided into 4 preoperative groups based on the level of CA 19-9: none 1000 U/mL. CA 19-9 levels were associated with several of the TG parameters, including endogenous thrombin potential, peak, and time to peak. CA 19-9 did not associate with any of the coagulation biomarkers. Spiking of SHP with CA 19-9 increased TG but this was decreased by an antiTF antibody. Conclusions: CA 19-9 was associated with TG in patients prior to any pancreatic cancer treatments or signs of VTE. Some commercial sources of CA 19-9 enhanced TG in SHP seemingly due to contaminating TF.Peer reviewe