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[en] In Paper I of this series, we showed that the ratio between stripped-envelope (SE) supernova (SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses . Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ∼3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host about nine times as many SN impostors. Normal SNe Ia seem to be ∼30% more common in low-mass galaxies, making these galaxies better sources for homogeneous SN Ia cosmology samples. The relative rates of SNe IIb are consistent in both low- and high-mass galaxies. The same is true for broad-line SNe Ic, although our sample includes only two such objects. The results presented here are in tension with a similar analysis from the Palomar Transient Factory, especially as regards SNe IIb.
[en] A common problem in ultra-high energy cosmic ray physics is the comparison of energy spectra. The question is whether the spectra from two experiments or two regions of the sky agree within their statistical and systematic uncertainties. We develop a method to directly compare energy spectra for ultra-high energy cosmic rays from two different regions of the sky in the same experiment without reliance on agreement with a theoretical model of the energy spectra. The consistency between the two spectra is expressed in terms of a Bayes factor, defined here as the ratio of the likelihood of the two-parent source hypothesis to the likelihood of the one-parent source hypothesis. Unlike other methods, for example χ2 tests, the Bayes factor allows for the calculation of the posterior odds ratio and correctly accounts for non-Gaussian uncertainties. The latter is particularly important at the highest energies, where the number of events is very small.
[en] The probabilities of deviations between chronometric predictions and high-redshift quasar observations are examined. The main principles of the chronometric theory of Segal (1972) are discussed. The Schmidt et al. (1986) observations of 10 quasars in the range z = 0.7-2.7 and observations of eight quasars in the range z = 1.00-2.76 are compared with the observations of no quasars in the range z = 2.7-4.9 and z = 2.9-5.0, respectively, and the probabilities are calculated. Also the Koo and Kron (1986) observation of seven quasars with z greater than 2.2 is contrasted with the observation of 32 quasars in the range z = 0.9-3.1, and the probabilities are again estimated. It is noted that the observed high-redshift quasar cutoff shows no statistically significant departure from the predictions of the nonevolutionary and nonparametric chronometric cosmology. 8 references
[en] Circumbinary disks have been hypothesized to exist around a number of binary post-asymptotic giant branch (AGB) stars. Although most of the circumbinary disks have been inferred through the near-infrared (IR) excess, a few of them are strong emitters of molecular emission. Here we present high-angular resolution observations of the emission of 12CO and its isotopomer 13CO J = 2-1 line from the circumstellar envelope around the binary post-AGB star IRAS 08544 - 4431, which is one of the most prominent members of this class of objects. We find that the envelope is resolved in our observations and two separate components can be identified: (a) a central extended and strong component with very narrow linewidth between 2 and 6 km s-1; (b) a weak bipolar outflow with expansion velocity up to 8 km s-1. The central compact component possesses low and variable 12CO/13CO J = 2-1 line ratio, indicating optically thick emission of the main isotope. We estimate a molecular gas mass of 0.0047 M sun for this component based on the optically thinner 13CO J = 2-1 line. We discuss the relation of the molecular envelope and the circumbinary disk inferred from near-IR excess and compare with other known cases where the distribution of molecular gas has been imaged at high angular resolution.
[en] The common assumption that is the dominant ionizing source for the Orion Nebula is critically examined. This assumption underlies much of the existing analysis of the nebula. In this paper we establish through comparison of the relative strengths of emission lines with expectations from Cloudy models and through the direction of the bright edges of proplyds that , which lies beyond the Bright Bar, also plays an important role. does dominate ionization in the inner part of the Orion Nebula, but outside of the Bright Bar as far as the southeast boundary of the Extended Orion Nebula, is the dominant source. In addition to identifying the ionizing star in sample regions, we were able to locate those portions of the nebula in 3D. This analysis illustrates the power of MUSE spectral imaging observations to identify sources of ionization in extended regions.
[en] A comparison was made between two sets of frequencies of intermediate-degree solar p-mode oscillations obtained in late 1981 and mid-1984. Good agreement was found at the 0.02 microHz level despite the 2.6 yr interval separating the two sets of observations. In particular, a comparison was made between the frequencies of 573 modes obtained at the South Pole during December 24-25, 1981 and those of the same modes as observed at the Mount Wilson Observatory 60-ft Solar Tower during July 29-August 13, 1984. The present results are consistent with no change in intermediate-degree p-mode frequencies between late 1981 and mid-1985. 17 references
[en] The Maunder Minimum (MM), which occurred between 1645 and 1715, is mainly known as an almost spotless period on the Sun. We analyze the nominal number of sunspot groups for each observer individually. Comparing the sunspot drawings and textual reports, we conclude that the latter underestimate the number of sunspots. We also argue that the different points of view of observers in the seventeenth century on the origin of sunspots resulted in the underestimation of sunspot groups or even gaps in observational reports. We demonstrate that Jean Picard and Giovanni Domenico Cassini of the Paris Observatory did not report any sunspots, while other observers reported on the occurrence of spots. Moreover, compared with other observers, La Hire underestimated the solar activity. The MM looks like an ordinary secular minimum with a depressed 11 yr solar cyclicity
[en] We report new spectroscopic and photometric observations of the main-sequence, detached, eccentric, double-lined eclipsing binary V541 Cyg (P = 15.34 days, e = 0.468). Using these observations together with existing measurements, we determine the component masses and radii to better than 1% precision: , , , and . The nearly identical B9.5 stars have estimated effective temperatures of 10650 ± 200 K and 10350 ± 200 K. A comparison of these properties with current stellar evolution models shows excellent agreement at an age of about 190 Myr and [Fe/H] ≈ −0.18. Both components are found to be rotating at the pseudo-synchronous rate. The system displays a slow periastron advance that is dominated by general relativity (GR), and has previously been claimed to be slower than predicted by theory. Our new measurement, deg century−1, has an 88% contribution from GR and agrees with the expected rate within the uncertainties. We also clarify the use of the gravity darkening coefficients in the light-curve fitting Eclipsing Binary Orbit Program (EBOP), a version of which we use here.
[en] Asteroseismology is a useful tool that is usually used to probe stellar interiors and to determine stellar fundamental parameters, such as stellar mass, radius, and surface gravity. In order to probe stellar interiors, making comparisons between observations and models is usually used with the -minimization method. The work of Wu and Li reported that the best parameter determined by the -matching process is the acoustic radius for pure p-mode oscillations. In the present work, based on the theoretical calculations of Wu and Li, we will independently analyze the seismic observations of KIC 6225718 to determine its fundamental parameters and to investigate its interior properties. First, in order to test the method, we use it in the Sun to determine its fundamental parameters and to investigate interiors. Second, we independently determine the fundamental parameters of KIC 6225718 without any other non-seismic constraint. Therefore, those determined fundamental parameters are independent of those determined by other methods. They can be regarded as independent references in other analyses. Finally, we analyze the stellar internal structure and find that KIC 6225718 has a convective core with the size of 0.078–0.092 . Its overshooting parameter in the core is around 0.010. In addition, its center hydrogen is about 0.264–0.355.
[en] The stellar obliquity of a transiting planetary system can be constrained by combining measurements of the star's rotation period, radius, and projected rotational velocity. Here, we present a hierarchical Bayesian technique for recovering the obliquity distribution of a population of transiting planetary systems and apply it to a sample of 70 Kepler objects of interest. With ≈95% confidence, we find that the obliquities of stars with only a single detected transiting planet are systematically larger than those with multiple detected transiting planets. This suggests that a substantial fraction of Kepler's single-transiting systems represent dynamically hotter, less orderly systems than the 'pancake-flat' multiple-transiting systems.