cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Modeling the signatures of interaction in Type II supernovae: UV emission, high-velocity features, broad-boxy profiles
Creators: name: Dessart, Luc
name: Hillier, D. John
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Because mass loss is a fundamental phenomenon in massive stars, interaction with circumstellar material (CSM) should be universal in core-collapse supernovae (SNe). Leaving aside the extreme CSM density, extent, or mass typically encountered in Type IIn SNe, we investigate the diverse long-term radiative signatures of interaction between a Type II SN ejecta and CSM corresponding to mass loss rates up to 10$^{-3}$ $M_{\odot}$ yr$^{-1}$. Because these CSM are relatively tenuous and optically-thin to electron-scattering beyond a few stellar radii, radiation hydrodynamics is not essential and one may treat the interaction directly as an additional power source in the non-local thermodynamic equilibrium radiative transfer problem. The CSM accumulated since shock breakout forms a dense shell in the outer ejecta and leads to high-velocity absorption features in spectral lines, even for negligible shock power. Besides Balmer lines, such features may appear in NaID, HeI lines etc. A stronger interaction strengthens the continuum flux (preferentially in the UV), quenches the absorption of P-Cygni profiles, boosts the MgII $λλ$ $2795,2802$ doublet, and fosters the production of a broad boxy H$α$ emission component. The rise in ionization in the outer ejecta may quench some lines (e.g., the CaII near-infrared triplet). The interaction power emerges preferentially in the UV, in particular at later times, shifting the optical color to the blue, but increasing modestly the optical luminosity. Strong thermalization and clumping seem to be required to make an interaction superluminous in the optical. The UV range contains essential signatures that provide critical constraints to infer the mass loss history and inner workings of core-collapse SN progenitors at death.
description: Accepted in A&A Letters
The rotation of planet-hosting stars
Creators: name: Sibony, Yves
name: Helled, Ravit
name: Feldmann, Robert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Understanding the distribution of angular momentum during the formation of planetary systems is a key topic in astrophysics. Data from the $\textit{Kepler}$ and $\textit{Gaia}$ missions allow to investigate whether stellar rotation is correlated with the presence of planets around Sun-like stars. Here, we perform a statistical analysis of the rotation period of 493 planet-hosting stars. These are matched to a control sample, without detected planets, with similar effective temperatures, masses, radii, metallicities, and ages. We find that planet-hosting stars rotate on average $1.63 \pm 0.40$ days slower. The difference in rotation is statistically significant both in samples including and not including planets confirmed by radial velocity follow-up observations. We also analyse the dependence of rotation distribution on various stellar and planetary properties. Our results could potentially be explained by planet detection biases depending on the rotation period of their host stars in both RV and transit methods. Alternatively, they could point to a physical link between the existence of planets and stellar rotation, emphasising the need to understand the role of angular momentum in the formation and evolution planetary systems.
description: 10 pages, 8 figures, 3 Appendix sections (10 pages, 13 figures). Accepted in MNRAS on April 4 2022
Exact percolation probabilities for a square lattice: Site percolation on a plane, cylinder, and torus
Creators: name: Akhunzhanov, Renat K.
name: Eserkepov, Andrei V.
name: Tarasevich, Yuri Yu.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We have found analytical expressions (polynomials) of the percolation probability for site percolation on a square lattice of size $L \times L$ sites when considering a plane (the crossing probability in a given direction), a cylinder (spanning probability), and a torus (wrapping probability along one direction). Since some polynomials are extremely cumbersome, they are presented as separate files in Supplemental material. The system sizes for which this was feasible varied up to $L=17$ for a plane, up to $L=16$ for a cylinder, and up to $L=12$ for a torus. To obtain a percolation probability polynomial, all possible combinations of occupied and empty sites have to be taken into account. However, using dynamic programming along with some ideas related to the topology, we offer an algorithm which allows a significant reduction in the number of configurations requiring consideration. A rigorous formal description of the algorithm is presented. Divisibility properties of the polynomials have been rigorously proved. Reliability of the polynomials obtained have been confirmed by the divisibility tests. The wrapping probability polynomials on a torus provide a better estimate of the percolation threshold than that from the spanning probability polynomials. Surprisingly, even a naive finite size scaling analysis allows an estimate to be obtained of the percolation threshold $p_c = 0.59269$.
description: 18 pages, 39 references, 8 figures, 2 tables, supplement, accepted manuscript in J. Phys. A: Fine Latticework: Celebrating the Craftsmanship of Robert M. Ziff in Honour of his 70th Birthday https://iopscience.iop.org/journal/1751-8121/page/fine-latticework
$^{57}$Zn $β$-delayed proton emission establishes the $^{56}$Ni $rp$-process waiting point bypass
Creators: name: Saxena, M.
name: Ong, W. -J
name: Meisel, Z.
name: Hoff, D. E. M.
name: Smirnova, N.
name: Bender, P. C.
name: Burcher, S. P.
name: Carpenter, M. P.
name: Carroll, J. J.
name: Chester, A.
name: Chiara, C. J.
name: Conaway, R.
name: Copp, P. A.
name: Crider, B. P.
name: Derkin, J.
name: Estrade, A.
name: Hamad, G.
name: Harke, J. T.
name: Jain, R.
name: Jayatissa, H.
name: Liddick, S. N.
name: Longfellow, B.
name: Mogannam, M.
name: Montes, F.
name: Nepal, N.
name: Ogunbeku, T. H.
name: Richard, A. L.
name: Schatz, H.
name: Soltesz, D.
name: Subedi, S. K.
name: Sultana, I.
name: Tamashiro, A. S.
name: Tripathi, V.
name: Xiaog, Y.
name: Zink, R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We measured the $^{57}$Zn $β$-delayed proton ($β$p) and $γ$ emission at the National Superconducting Cyclotron Laboratory. We find a $^{57}$Zn half-life of 43.6 $\pm$ 0.2 ms, $β$p branching ratio of (84.7 $\pm$ 1.4)%, and identify four transitions corresponding to the exotic $β$-$γ$-$p$ decay mode, the second such identification in the $f p$-shell. The $p/γ$ ratio was used to correct for isospin mixing while determining the $^{57}$Zn mass via the isobaric multiplet mass equation. Previously, it was uncertain as to whether the rp-process flow could bypass the textbook waiting point $^{56}$Ni for astrophysical conditions relevant to Type-I X-ray bursts. Our results definitively establish the existence of the $^{56}$Ni bypass, with 14-17% of the $rp$-process flow taking this route.
Discovery of cyclotron and narrow Fe K$_α$ lines in HMXB GRO J1750-27
Creators: name: Sharma, Prince
name: Jain, Chetana
name: Dutta, Anjan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report on timing and spectral analysis of transient Be X-ray pulsar GRO J1750-27 by using the Nuclear Spectroscopic Telescope Array (NuSTAR) observation from September 2021. This is the fourth outburst of the system since 1995. The NuSTAR observation was performed during the rising phase of the outburst. Pulsations at a period of 4.450710(1) s were observed in the 3-60 keV energy range. The average pulse profile comprised of a broad peak with a weak secondary peak which evolved with energy. We did not find any appreciable variation in the X-ray emission during this observation. The broad-band phase-averaged spectrum is described by a blackbody, a powerlaw or Comptonization component. We report discovery of Fe K$_α$ line at 6.4 keV along with presence of two cyclotron resonant scattering features around 36 and 42 keV. These lines indicate a magnetic field strength of $3.7_{-0.3}^{+0.1} \times 10^{12}$ and $4.4 \pm 0.1 \times 10^{12}$ G for the neutron star. We have estimated a source distance of $\sim$ 13.6-16.4 kpc based on the accretion-disc torque models.
description: 8 pages, 9 Figures, 1 Table, Updated and accepted version for publication in MNRAS
Is Terzan 5 the remnant of a building block of the Galactic bulge? Evidence from APOGEE
Creators: name: Taylor, Dominic J.
name: Mason, Andrew C.
name: Schiavon, Ricardo P.
name: Horta, Danny
name: Nataf, David M.
name: Geisler, Doug
name: Kisku, Shobhit
name: Phillips, Siân G.
name: Cohen, Roger E.
name: Fernández-Trincado, José G.
name: Beers, Timothy C.
name: Bizyaev, Dmitry
name: García-Hernández, Domingo Aníbal
name: Lane, Richard R.
name: Longa-Peña, Penélope
name: Minniti, Dante
name: Muñoz, Cesar
name: Pan, Kaike
name: Villanova, Sandro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: It has been proposed that the globular cluster-like system Terzan 5 is the surviving remnant of a primordial building block of the Milky Way bulge, mainly due to the age/metallicity spread and the distribution of its stars in the $α$-Fe plane. We employ Sloan Digital Sky Survey (SDSS-IV) data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to test this hypothesis. Adopting a random sampling technique, we contrast the abundances of 10 elements in Terzan 5 stars with those of their bulge field counterparts with comparable atmospheric parameters, finding that they differ at statistically significant levels. Abundances between the two groups differ by more than 1$σ$ in Ca, Mn, C, O, and Al, and more than 2$σ$ in Si and Mg. Terzan 5 stars have lower [$α$/Fe] and higher [Mn/Fe] than their bulge counterparts. Given those differences, we conclude that Terzan 5 is not the remnant of a $major$ building block of the bulge. We also estimate the stellar mass of the Terzan 5 progenitor based on predictions by the Evolution and Assembly of GaLaxies and their Environments (EAGLE) suite of cosmological numerical simulations, concluding that it may have been as low as $\sim3\times10^8$ M$_\odot$ so that it was likely unable to significantly influence the mean chemistry of the bulge/inner disk, which is significantly more massive ($\sim10^{10}$ M$_\odot$). We briefly discuss existing scenarios for the nature of Terzan 5 and propose an observational test that may help elucidate its origin.
description: 15 pages, 10 figures, accepted for publication by MNRAS
New evidences in IRDC G333.73+0.37: colliding filamentary clouds, hub-filament system, and embedded cores
Creators: name: Dewangan, L. K.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: To unravel the star formation process, we present a multi-scale and multi-wavelength study of the filamentary infrared dark cloud (IRDC) G333.73+0.37, which hosts previously known two HII regions located at its center. Each HII region is associated with a mid-infrared source, and is excited by a massive OB star. Two filamentary structures and a hub-filament system (HFS) associated with one HII region are investigated in absorption using the Spitzer 8.0 $μ$m image. The $^{13}$CO(J = 2-1) and C$^{18}$O(J = 2-1) line data reveal two velocity components (around $-$35.5 and $-$33.5 km s$^{-1}$) toward the IRDC, favouring the presence of two filamentary clouds at different velocities. Nonthermal (or turbulent) motions are depicted in the IRDC using the C$^{18}$O line data. The spatial distribution of young stellar objects (YSOs) identified using the VVV near-infrared data traces star formation activities in the IRDC. Low-mass cores are identified toward both the HII regions using the ALMA 1.38 mm continuum map. The VLT/NACO adaptive-optics L$^{\prime}$-band images show the presence of at least three point-like sources and the absence of small-scale features in the inner 4000 AU around YSOs NIR31 and MIR 16 located toward the HII regions. The HII regions and groups of YSO are observed toward the central part of the IRDC, where the two filamentary clouds intersect. A scenario of cloud-cloud collision or converging flows in the IRDC seems to be applicable, which may explain star formation activities including HFS and massive stars.
description: 19 pages, 12 figures; Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) Journal
Measuring weak lensing masses on individual clusters
Creators: name: Murray, Calum
name: Bartlett, James G.
name: Artis, Emmanuel
name: Melin, Jean-Baptiste
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present weak lensing mass estimates for a sample of 458 galaxy clusters from the redMaPPer Sloan Digital Sky Survey DR8 catalogue using Hyper Suprime-Cam weak lensing data. We develop a method to quickly estimate cluster masses from weak lensing shear and use this method to estimate weak lensing masses for each of the galaxy clusters in our sample. Subsequently, we constrain the mass-richness relation as well as the intrinsic scatter between the cluster richness and the measured weak lensing masses. When calculating the mass-richness relation for all clusters with a richness $λ>20$, we find a tension in the slope of the mass-richness relation with the Dark Energy Survey Year 1 stacked weak lensing analysis. For a reduced sample of clusters with a richness $λ>40$, our results are consistent with the Dark Energy Survey Year 1 analysis.
description: 7 pages, 7 figures. Monthly Notices of the Royal Astronomical Society (2022)
Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS -- IV. Discovery of two new GW Vir stars: TIC0403800675 and TIC1989122424
Creators: name: Uzundag, Murat
name: Corsico, Alejandro H.
name: Kepler, S. O.
name: Althaus, Leandro G.
name: Werner, Klaus
name: Reindl, Nicole
name: Vuckovic, Maja
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present two new GW Vir-type pulsating white dwarf stars, TIC\,0403800675 (WD\,J115727.68-280349.64) and TIC\,1989122424 (WD J211738.38-552801.18) discovered in the Transiting Exoplanet Survey Satellite (TESS) photometric data. For both stars, the TESS light curves reveal the presence of oscillations with periods in a narrow range between 400 and 410\,s, which are associated with typical gravity ($g$)-modes. Follow-up ground-based spectroscopy shows that both stars have similar effective temperature ($T_\mathrm{eff} = 110,000 \pm 10,000$\,K) and surface gravity ($\log g = 7.5 \pm 0.5$), but different He/C composition (mass fractions): He\,=\,0.75 and C\,=\,0.25 for TIC\,0403800675, and He\,=\,0.50 and C\,=\,0.50 for TIC\,1989122424. By performing a fit to their spectral energy distributions, we found for both stars radii and luminosities of $R=0.019\pm0.002\,R_\odot$ and $\log(L/L_\odot)=1.68^{+0.15}_{-0.24}$, respectively. By employing evolutionary tracks of PG~1159 stars, we find the masses of both stars to be $0.56\pm0.18 M_{\odot}$ from the $\log g$-$T_\mathrm{eff}$ diagram and $0.60^{+0.11}_{-0.09} M_{\odot}$ from the Hertzsprung Russell diagram.
description: 8 Pages. arXiv admin note: text overlap with arXiv:2108.11093
Exploring the cosmic 21-cm signal from the Epoch of Reionisation using the Wavelet Scattering Transform
Creators: name: Greig, Bradley
name: Ting, Yuan-Sen
name: Kaurov, Alexander A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Detecting the cosmic 21-cm signal during the Epoch of Reionisation and Cosmic Dawn will reveal insights into the properties of the first galaxies and advance cosmological parameter estimation. Until recently, the primary focus for astrophysical parameter inference from the 21-cm signal centred on the power spectrum (PS). However, the cosmic 21-cm signal is highly non-Gaussian rendering the PS sub-optimal for characterising the cosmic signal. In this work, we introduce a new technique to analyse the non-Gaussian information in images of the 21-cm signal called the Wavelet Scattering Transform (WST). This approach closely mirrors that of convolutional neural networks with the added advantage of not requiring tuning or training of a neural network. Instead, it compresses the 2D spatial information into a set of coefficients making it easier to interpret while also providing a robust statistical description of the non-Gaussian information contained in the cosmic 21-cm signal. First, we explore the application of the WST to mock 21-cm images to gain valuable physical insights by comparing to the known behaviour from the 21-cm PS. Then we quantitatively explore the WST applied to the 21-cm signal by extracting astrophysical parameter constraints using Fisher Matrices from a realistic 1000 hr mock observation with the Square Kilometre Array. We find that: (i) the WST applied only to 2D images can outperform the 3D spherically averaged 21-cm PS, (ii) the excision of foreground contaminated modes can degrade the constraining power by a factor of ~1.5-2 with the WST and (iii) higher cadences between the 21-cm images can further improve the constraining power.
description: 25 pages, 16 figures and 2 tables. Accepted for publication in MNRAS
“Poetisierung als kritisches Verfahren – ‘Arbeit’ in der deutschen Frühromantik”, in: Narrative der Arbeit / Narratives of Work, ed. Franz-Josef Deiters et al. Freiburg i. Br./Berlin/Wien: Rombach, 2009, pp. 33-49.
Creators: name: Franz-Josef Deiters
Publisher: name: Monash University
Year: 2016
Subjects: subject: 200512 Literature in German
subject: FOS: Languages and literature

description: Dieser Aufsatz reflektiert das Thema Arbeit im Übergang von der Weimarer Klassik zur deutschen Frühromantik.
Об использовании метан-водородных смесей в двигателях внутреннего сгорания
Creators: name: Арутюнов Владимир Сергеевич
name: Беляев Андрей Александрович
name: Трошин Кирилл Яковлевич
name: Арутюнов Артем Владимирович
name: Царенко Алексей Александрович
name: Никитин Алексей Витальевич
Publisher: name: НефтеГазоХимия
Year: 2019
Subjects: метан
водород
задержка самовоспламенения
двигатель внутреннего сгорания
метановое число
октановое число.

description: Показано, что влияние добавок водорода на самовоспламенение метана носит сложный характер. Оно сильно зависит от условий проведения процесса. Неоднозначное влияние концентрации водорода на самовоспламенение метан-водородных смесей ставит под сомнение практическую целесообразность использования таких смесей в качестве репера для определения детонационных характеристик газовых топлив. В связи с этим большое значение приобретает вопрос о возможности определения детонационных характеристик газовых топлив на основе кинетического моделирования их воспламенения в условиях реального двигателя.
Word Learning: Homophony and the Distribution of Learning Exemplars
Creators: name: Dautriche, Isabelle
name: Chemla, Emmanuel
name: Christophe, Anne
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Medicine
subject: Neuroscience
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: Science Policy
subject: 111714 Mental Health
subject: FOS: Health sciences
subject: 60506 Virology

description: How do children infer the meaning of a word? Current accounts of word learning assume that children expect a word to map onto exactly one concept whose members form a coherent category. If this assumption was strictly true, children should infer that a homophone, such as “bat”, refers to a single superordinate category that encompasses both animal-bats and baseball-bats. The current study explores the situations that lead children to postulate that a single word form maps onto several distinct meanings, rather than a single superordinate meaning. Three experiments showed that adults and 5-year-old French children use information about the sampling of learning exemplars (and in particular the fact that they can be regrouped in two distinct clusters in conceptual space) to postulate homophony. This unexplored sensitivity and the very possibility of homophony are critically missing from current word learning accounts.
A study of the F-giant star $θ$ Scorpii A: a post-merger rapid rotator?
Creators: name: Lewis, Fiona
name: Bailey, Jeremy
name: Cotton, Daniel V.
name: Howarth, Ian D.
name: Kedziora-Chudczer, Lucyna
name: van Leeuwen, Floor
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: We report high-precision observations of the linear polarization of the F1$\,$III star $θ$ Scorpii. The polarization has a wavelength dependence of the form expected for a rapid rotator, but with an amplitude several times larger than seen in otherwise similar main-sequence stars. This confirms the expectation that lower-gravity stars should have stronger rotational-polarization signatures as a consequence of the density dependence of the ratio of scattering to absorption opacities. By modelling the polarization, together with additional observational constraints (incorporating a revised analysis of Hipparcos astrometry, which clarifies the system's binary status), we determine a set of precise stellar parameters, including a rotation rate $ω\, (= Ω/Ω_{\rm c})\ge 0.94$, polar gravity $\log{g_p} = 2.091 ^{+0.042}_{-0.039}$ (dex cgs), mass $3.10 ^{+0.37}_{-0.32}$ solar masses, and luminosity $\log(L/Lsun) =3.149^{+0.041}_{-0.028}$. These values are incompatible with evolutionary models of single rotating stars, with the star rotating too rapidly for its evolutionary stage, and being undermassive for its luminosity. We conclude that $θ$ Sco A is most probably the product of a binary merger.
description: 12 pages, 10 figures, Accepted by MNRAS
First Census of Gas-phase Metallicity Gradients of Star-forming Galaxies in Overdense Environments at Cosmic Noon
Creators: name: Li, Zihao
name: Wang, Xin
name: Cai, Zheng
name: Shi, Dong Dong
name: Fan, Xiaohui
name: Zheng, Xian Zhong
name: Malkan, Matthew A.
name: Teplitz, Harry I.
name: Henry, Alaina L.
name: Bian, Fuyan
name: Colbert, James
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We report the first spatially resolved measurements of gas-phase metallicity radial gradients in star-forming galaxies in overdense environments at $z\gtrsim2$. The spectroscopic data are acquired by the \mg\ survey, a Hubble Space Telescope (HST) cycle-28 medium program. This program is obtaining 45 orbits of WFC3/IR grism spectroscopy in the density peak regions of three massive galaxy protoclusters (BOSS 1244, BOSS 1542 and BOSS 1441) at $z=2-3$. Our sample in the BOSS 1244 field consists of 20 galaxies with stellar-mass ranging from $10^{9.0}$ to $10^{10.3}$ \Msun\ , star formation rate (SFR) from 10 to 240 \Msun\,yr$^{-1}$, and global gas-phase metallicity (\oh) from 8.2 to 8.6. At $1σ$ confidence level, 2/20 galaxies in our sample show positive (inverted) gradients -- the relative abundance of oxygen increasing with galactocentric radius, opposite the usual trend. Furthermore, 1/20 shows negative gradients and 17/20 are consistent with flat gradients. This high fraction of flat/inverted gradients is uncommon in simulations and previous observations conducted in blank fields at similar redshifts. To understand this, we investigate the correlations among various observed properties of our sample galaxies. We find an anticorrelation between metallicity gradient and global metallicity of our galaxies residing in extreme overdensities, and a marked deficiency of metallicity in our massive galaxies as compared to their coeval field counterparts. We conclude that the cold-mode gas accretion plays an active role in shaping the chemical evolution of galaxies in the protocluster environments, diluting their central chemical abundance, and flattening/inverting their metallicity gradients.
description: 13 pages, 6 figures, 1 table. Accepted for publication in ApJL
The impact of the uncertainties in the 12C(α,γ)16O reaction rate on the evolution of low- to intermediate-mass stars
Creators: name: Pepper, Ben T.
name: Istrate, A. G.
name: Romero, A. D.
name: Kepler, S. O.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: One of the largest uncertainties in stellar evolutionary computations is the accuracy of the considered reaction rates. The 12C(alpha,gamma)16O reaction is particularly important for the study of low- and intermediate-mass stars as it determines the final C/O ratio in the core which influences the white dwarf cooling evolution. Thus, there is a need for a study of how the computations of white dwarfs and their progenitors that are made to date may be affected by the uncertainties of the 12C(alpha,gamma)16O reaction rates. In this work we compute fully evolutionary sequences using the MESA code with initial masses in the range of 0.90 <= Mi/Msun <= 3.05. We consider different adopted reaction rates, obtained from the literature, as well as the extreme limits within their uncertainties. As expected, we find that previous to the core helium burning stage there are no changes to the evolution of the stars. However, the subsequent stages are all affected by the uncertainties of the considered reaction rate. In particular, we find differences to the convective core mass during the core helium burning stage which may affect pulsation properties of subdwarfs, the number of thermal pulses during the asymptotic giant branch and trends between final oxygen abundance in the core and the progenitor masses of the remnant white dwarfs.
description: 15 pages, 15 figures, 1 table
MIGHTEE-HI: The relation between the HI gas in galaxies and the cosmic web
Creators: name: Tudorache, Madalina N.
name: Jarvis, M. J.
name: Heywood, I.
name: Ponomareva, A. A.
name: Maddox, N.
name: Frank, B. S.
name: Adams, N. J.
name: Bowler, R. A. A.
name: Whittam, I. H.
name: Baes, M.
name: Pan, H.
name: Rajohnson, S. H. A.
name: Sinigaglia, F.
name: Spekkens, K.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study the 3D axis of rotation (3D spin) of 77 HI galaxies from the MIGHTEE-HI Early Science observations, and its relation to the filaments of the cosmic web. For this HI-selected sample, the alignment between the spin axis and the closest filament ($\lvert \cos ψ\rvert$) is higher for galaxies closer to the filaments, with $\langle\lvert \cos ψ\rvert\rangle= 0.66 \pm 0.04$ for galaxies $<5$ Mpc from their closest filament compared to $\langle\lvert \cos ψ\rvert\rangle= 0.37 \pm 0.08$ for galaxies at $5 < d <10$ Mpc. We find that galaxies with a low HI-to-stellar mass ratio ($\log_{10}(M_{\rm HI}/M_{\star}) < 0.11$) are more aligned with their closest filaments, with $\langle\lvert \cos ψ\rvert\rangle= 0.58 \pm 0.04$; whilst galaxies with ($\log_{10}(M_{\rm HI}/M_{\star}) > 0.11$) tend to be mis-aligned, with $\langle\lvert \cos ψ\rvert\rangle= 0.44 \pm 0.04$. We find tentative evidence that the spin axis of HI-selected galaxies tend to be aligned with associated filaments ($d<10$ Mpc), but this depends on the gas fractions. Galaxies that have accumulated more stellar mass compared to their gas mass tend towards stronger alignment. Our results suggest that those galaxies that have accrued high gas fraction with respect to their stellar mass may have had their spin axis alignment with the filament disrupted by a recent gas-rich merger, whereas the spin vector for those galaxies in which the neutral gas has not been strongly replenished through a recent merger tend to orientate towards alignment with the filament. We also investigate the spin transition between galaxies with a high HI content and a low HI content at a threshold of $M_{\mathrm{HI}}\approx 10^{9.5} M_{\odot}$ found in simulations, however we find no evidence for such a transition with the current data.
description: 11 pages, 9 figures, 5 tables, accepted for publication in MNRAS
Credibility in science: The case of the study of the relationship between cognition, brain and exercise
Creators: name: Sanabria, Daniel
Publisher: name: Zenodo
Year: 2020
Subjects: physical exercise, physical activity, cognition, brain, executive function, cognitive control, evidence

description: The talk discusses about the relationship between (chronic) physical exercise, brain and cognition, highlighting that the current evidence regarding the beneficial effects (at the cognitive and brain level) of exercising might not be as solid as one might think.
Cosmological nanolensing by dense gas clouds
Creators: name: Tuntsov, Artem
name: Walker, Mark
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study the influence of a cosmological population of dense gas clouds on distant sources, with emphasis on quasar optical variability. In addition to gravitational lensing such clouds affect flux measurements via refraction in the neutral gas and via dust extinction, leading to a variety of possible light curves even in the low optical depth limit. We classify and illustrate the types of light curves that can arise. For sources as large as quasars we show that gravitational lensing and extinction are the dominant effects, with gas refraction playing only a minor role. We find that clouds with mass ~10^{-4.5+/-0.5} M_\odot can reproduce the observed distribution of quasar variation amplitudes, but only if such clouds make up a large fraction of the closure density. In that case there may also be substantial extinction of distant optical sources, which can in principle be constrained by data on "standard candles" such as type Ia supernovae. Unfortunately that extinction is essentially grey, even when the material opacity is strongly wavelength dependent, making it difficult to distinguish from the influence of the background geometry. We propose a novel statistical test of the origin of quasar variability, based on the angular structure of the variation timescale for a large number of quasars distributed all over the sky. If quasar variability is primarily due to nanolensing that angular structure is expected to include a quadrupole term of amplitude $\sim5\%$, which ought to be measurable with future data from the Gaia mission.
description: 19 pages, 6 figures plus an appendix; accepted for publication in MNRAS
Discovery of Nine Super Li-rich Unevolved Stars from the LAMOST Survey
Creators: name: Yan, T. -S.
name: Shi, J. -R.
name: Wang, L.
name: Yan, H. -L.
name: Zhou, Z. -M.
name: Zhou, Y. -T.
name: Fang, X. -S.
name: Li, C. -Q.
name: Chen, T. -Y.
name: Xie, X. -J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution spectroscopic survey (MRS), we report the discovery of nine super Li-rich unevolved stars with A(Li) $>$ 3.8 dex. These objects show unusually high levels of lithium abundances up to three times higher than the meteoritic value of 3.3 dex, which indicates that they must have experienced a history of lithium enrichment. It is found that seven of our program stars are fast rotators with $vsini>9$ km\,s$^{-1}$, which suggests that the accretion of circumstellar matter may be the main contributor to the lithium enhancement of these unevolved stars, however, other sources cannot be excluded.
description: 10 pages, 3 figures
Early Evolution of a Newborn Magnetar with Strong Precession Motion in GRB 180620A
Creators: name: Zou, Le
name: Liang, En-Wei
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The observed early X-ray plateau in the afterglow lightcurves of some gamma-ray bursts (GRBs) is attributed to the dipole radiations (DRs) of a newborn magnetar. A quasi-periodic oscillation (QPO) signal in the plateau would be strong evidence of the magnetar precession motion. By making a time-frequency domain analysis for the X-ray afterglow lightcurve of GRB 180620A, we find a QPO signal of $\sim650$ seconds in its early X-ray plateau. We fit the lightcurve with a magnetar precession model by adopting the Markov chain Monte Carlo algorithm. The observed lightcurve and the QPO signal are well represented with our model. The derived magnetic field strength of the magnetar is $B_{\rm p}= (1.02^{+0.59}_{-0.61})\times10^{15}$~G. It rapidly spins down with angular velocity evolving as $Ω_{s} \propto(1+t/τ_{\rm sd})^{-0.96}$, where $τ_{\rm sd}=9430$~s. Its precession velocity evolution is even faster than $Ω_s$, i.e. $Ω_{ p}\propto (1+t/τ_{p})^{-2.18\pm0.11}$, where $τ_{p}=2239\pm206$~s. The inferred braking index is $n=2.04$. We argue that the extra energy loss via the magnetospheric processes results in its rapid spin-down, a low braking index of the magnetar, and the strong precession motion.
description: 5 pages, 3 figures, accepted for publication in MNRAS Letters
Влияние магнитного поля на реологические свойства тяжелых высоковязких нефтей
Creators: name: Леонтьев Александр Юрьевич
name: Полетаева Ольга Юрьевна
name: Шакиров Руслан Азатович
name: Хасанов Ильнур Ильдарович
name: Бабаев Эльбей Расимович
Publisher: name: НефтеГазоХимия
Year: 2019
Subjects: парафин
АСПО
магнитная обработка
высоковязкие тяжелые нефти
прямой нагрев
нефтяная дисперсная система
кривые течения
магнитная обработка.

description: В работе было исследовано воздействие магнитного поля на тяжелые высоковязкие нефти. Приведены современные теории, объясняющие действие магнитной обработки нефтей. Рассмотрены исследования по влиянию магнитного поля на нефть на различных этапах в процессе ее добычи и транспорта. Проведены эксперименты, в которых изучалось изменение вязкости от продолжительности воздействия магнитного поля. Объектами исследования были использованы высоковязкие нефти Волго-Уральского нефтегазоносного бассейна вязкостью свыше 2200 мПа·с и плотностью выше 900 м3/кг. В процессе исследования снимались кривые течения нефти как при прямом нагреве с шагом в 10 °С (была построена зависимость динамической вязкости от температуры), так и кривые течения нефти после воздействия магнитным полем. Установлено влияние температуры на вязкость образцов нефти при прямом нагреве и воздействие магнитного поля. Эксперименты показали, что нефть при магнитном воздействии изменяет свои реологические свойства в зависимости от времени обработки. Возможно, в процессе обработки образуется новая нефтяная дисперсная система, которая, в свою очередь, может не только улучшать реологические свойства, но и ухудшать их.
The OmegaWhite Survey for Short-Period Variable Stars VII: High amplitude, short period blue variables
Creators: name: Ramsay, G.
name: Woudt, P. A.
name: Kupfer, T.
name: van Roestel, J.
name: Patterson, K.
name: Warner, B.
name: Buckley, D. A. H.
name: Groot, P. J.
name: Heber, U.
name: Irrgang, A.
name: Jeffery, C. S.
name: Motsoaledi, M.
name: Schwartz, M. J.
name: Wevers, T.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Blue Large Amplitude Pulsators (BLAPs) are a relatively new class of blue variable stars showing periodic variations in their light curves with periods shorter than a few tens of mins and amplitudes of more than ten percent. We report nine blue variable stars identified in the OmegaWhite survey conducted using ESO's VST, which show a periodic modulation in the range 7-37 min and an amplitude in the range 0.11-0.28 mag. We have obtained a series of followup photometric and spectroscopic observations made primarily using SALT and telescopes at SAAO. We find four stars which we identify as BLAPs, one of which was previously known. One star, OW J0820--3301, appears to be a member of the V361 Hya class of pulsating stars and is spatially close to an extended nebula. One further star, OW J1819--2729, has characteristics similar to the sdAV pulsators. In contrast, OW J0815--3421 is a binary star containing an sdB and a white dwarf with an orbital period of 73.7 min, making it only one of six white dwarf-sdB binaries with an orbital period shorter than 80 min. Finally, high cadence photometry of four of the candidate BLAPs show features which we compare with notch-like features seen in the much longer period Cepheid pulsators.
description: Accepted by MNRAS
Перспективы использования синтез-газа для поддержания пластового давления при добыче нефти
Creators: name: Овчинников Кирилл Александрович
name: Борисевич Юрий Павлович
name: Трошина Ольга Сергеевна
name: Маслов Максим Павлович
Publisher: name: НефтеГазоХимия
Year: 2019
Subjects: синтез-газ
поддержание пластового давления
сайклингпроцесс.

description: Переориентация существующего производства конверсии попутного газа с получением технического водорода (в качестве основного продукта) и углекислого газа (в качестве побочного продукта) с нужд химической и нефтехимической промышленности на потребности нефтяной отрасли позволит не только расширить существующий рынок водорода, но и внедрить наконец в РФ принципиально новую разновидность сайклинг-процесса, не имеющую мировых аналогов, а также способствовать более быстрому исполнению известного указа президента РФ об уровне утилизации попутного газа в объеме не менее 95%.
Dust SEDs in Milky Way-like galaxies in the IllustrisTNG simulations based on the evolution of grain size distribution
Creators: name: Chang, Chiung-Yin
name: Huang, Yu-Hsiu
name: Hirashita, Hiroyuki
name: Cooper, Andrew P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: To understand how the evolution of grain size distribution in galaxies affects observed dust properties, we apply a post-processing dust evolution model to galaxy merger trees from the IllustrisTNG cosmological hydrodynamical simulation. Our dust model includes stellar dust production, sputtering in hot gas, dust growth by accretion and coagulation in the dense interstellar medium (ISM), and shattering in the diffuse ISM. We decompose the grain size distribution into different dust species depending on the elemental abundances and the dense ISM fraction given by the simulation. In our previous work, we focused on Milky Way (MW) analogs and reproduced the observed MW extinction curve. In this study, we compute dust spectral energy distributions (SEDs) for the MW analogues. Our simulated SEDs broadly reproduce the observed MW SED within their dispersion and so does the observational data of nearby galaxies, although they tend to underpredict the MW SED at short wavelengths where emission is dominated by polycyclic aromatic hydrocarbons (PAHs). We find that metallicity and dense gas fraction are the most critical factors for the SED shape, through their influence on coagulation and shattering.The overall success of our models in reproducing the MW SED further justifies the dust evolution processes included in the model and predicts the dispersion in the SEDs caused by the variety in the assembly history. We also show that the most significant increase in the dust SED occurs between redshifts $z\sim 3$ and 2 in the progenitors of the simulated MW-like galaxies.
description: 10 pages, 8 figure, accepted for publication in MNRAS
Обзор реакторов синтеза метанола и их характеристик
Creators: name: Гимаева Алина Рашитовна
name: Хасанов Ильнур Ильдарович
Publisher: name: НефтеГазоХимия
Year: 2019
Subjects: природный газ
метанол
реактор
конструкция
синтез метанола.

description: В настоящее время природный и попутный нефтяной газ прежде всего являются энергетическим сырьем. Химическая переработка природного и попутного нефтяного газа может стать одной из важнейших стратегических задач, которая позволит дать импульс для создания новых современных технологий. Одно из направлений переработки газового углеводородного сырья – производство метанола, являющегося одним из важнейших крупнотоннажных продуктов органического синтеза. В статье рассмотрены способы получения синтез-газа, необходимого для производства метанола. Приведены наиболее распространенные способы получения синтез-газа, широко используемые в промышленности. Также приведен обзор существующих и разрабатываемых реакторов синтеза метанола, изучены их характеристики, схемы и особенности принципа их работы.
Constraints on TESS albedos for five hot Jupiters
Creators: name: Blažek, Martin
name: Kabáth, Petr
name: Piette, Anjali A. A.
name: Madhusudhan, Nikku
name: Skarka, Marek
name: Šubjak, Ján
name: Anderson, David R.
name: Boffin, Henri M. J.
name: Cáceres, Claudio C.
name: Gibson, Neale P.
name: Hoyer, Sergio
name: Ivanov, Valentin D.
name: Rojo, Patricio M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Photometric observations of occultations of transiting exoplanets can place important constraints on the thermal emission and albedos of their atmospheres. We analyse photometric measurements and derive geometric albedo ($A_\mathrm{g}$) constraints for five hot Jupiters observed with TESS in the optical: WASP-18 b, WASP-36 b, WASP-43 b, WASP-50 b and WASP-51 b. For WASP-43 b, our results are complemented by a VLT/HAWK-I observation in the near-infrared at $2.09~μ$m. We derive the first geometric albedo constraints for WASP-50 b and WASP-51 b: $A_\mathrm{g}<0.445$ and $A_\mathrm{g}<0.368$, respectively. We find that WASP-43 b and WASP-18 b are both consistent with low geometric albedos ($A_\mathrm{g}<0.16$) even though they lie at opposite ends of the hot Jupiter temperature range with equilibrium temperatures of $\sim1400$ K and $\sim2500$ K, respectively. We report self-consistent atmospheric models which explain broadband observations for both planets from TESS, \HST, \Spitzer and VLT/HAWK-I. We find that the data of both hot Jupiters can be explained by thermal emission alone and inefficient day-night energy redistribution. The data do not require optical scattering from clouds/hazes, consistent with the low geometric albedos observed.
description: 21 pages, 7 figures
Synthesis of C3-dihydrofuran substituted coumarins via multicomponent approach
Creators: name: Venkata Swamy Tangeti
name: Ramesh Varma, K.
name: G. V. Siva Prasad
name: K. V. V. V. Satyanarayana
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Biochemistry
subject: Genetics
subject: FOS: Biological sciences
subject: Biotechnology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: Plant Biology
subject: Computational Biology

description: An efficient method was developed for the synthesis of dihydrofuran substituted coumarin from a one-pot, four-component reaction of 2-hydroxy aromatic aldehydes, 6-methyl, 4-hydroxy pyranone, aromatic aldehyde, and pyridinium ylide in the presence of tri-ethylamine under microwave irradiation. The reaction proceeds under solvent-free conditions to afford C3-dihydrofuran substituted coumarin in a diastereoselective manner in good yields (71–89%).
Ultracool dwarfs identified using spectra in LAMOST DR7
Creators: name: Wang, You-Fen
name: Luo, A-Li
name: Chen, Wen-Ping
name: Jones, Hugh R. A.
name: Du, Bing
name: Li, Yin-Bi
name: Zhang, Shuo
name: Bai, Zhong-Rui
name: Kong, Xiao
name: Guo, Yan-Xin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: In this work, we identify 734 ultracool dwarfs with a spectral type of M6 or later, including one L0. Of this sample, 625 were studied spectroscopically for the first time. All of these ultracool dwarfs are within 360~pc, with a \textit{Gaia} G magnitude brighter than ~19.2 mag. By studying the spectra and checking their stellar parameters (Teff, logg, and [FeH] derived with the LAMOST pipeline, we found their cool red nature and their metallicity to be consistent with the nature of Galactic thin-disk objects. Furthermore, 77 of them show lithium absorption lines at 6708A, further indicating their young ages and substellar nature. Kinematics obtained through LAMOST radial velocities, along with the proper motion and parallax data from Gaia EDR3, also suggest that the majority of our targets are thin-disk objects. Kinematic ages were estimated through the relationship between the velocity dispersion and the average age for a certain population. Moreover, we identified 35 binaries, with 6 of them reported as binaries for the first time.
description: 13 pages, 11 figures, published in A&A, Volume 660. A38 (2022)
Особенности осуществления процесса синтеза Фишера–Тропша в радиальных реакторах
Creators: name: Кононенко Анна Алексеевна
name: Сосна Михаил Хаймович
Publisher: name: НефтеГазоХимия
Year: 2019
Subjects: базовые масла
процесс GTL
синтез-газ
технология Фишера–Тропша
радиальный реактор
анализ
стационарный процесс.

description: В статье рассмотрены возможности создания производства базовых масел на основе технологии GTL в России. Проведен анализ преимуществ и недостатков радиальных реакторов. Рассмотрен ряд технологических требований, которым должен удовлетворять радиальный реактор. Проанализированы главные задачи ведения процесса в стационарном режиме работы для радиальных реакторов синтеза Фишера– Тропша. На основе полученных данных предложены рекомендации по их применению в России.
Продукты переработки древесины как альтернатива углеводородам нефти
Creators: name: Четвертнева Ирина Амировна
name: Каримов Олег Хасанович
name: Тептерева Галина Алексеевна
name: Исмаков Рустэм Адипович
Publisher: name: НефтеГазоХимия
Year: 2019
Subjects: целлюлоза
гемицеллюлозы
лигнин
лигносульфонаты
биотопливо
углеводороды.

description: В статье рассматриваются продукты переработки древесины как альтернативный источник промышленно востребованных углеводородов. Описаны структуры выделяемых биополимеров – целлюлозы, гемицеллюлоз, лигнина и его модификации. Показаны пути превращений природных полимеров, полученных при переработке древесины, в ценные продукты – низкомолекулярные вещества, мономеры, полимерные материалы, топливо.