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Parsec-scale cosmic-ray ionisation rate in Orion A. Socci, G. Sabatini, M. Padovani, S. Bovino, A. Hacar arXiv:2404.15754v1 Announce Type: new Abstract: Cosmic rays regulate the dynamics and the chemical processes in the densest and coldest regions of the ISM. Still, the determination of the cosmic-ray ionisation rate of H$_2$ (${zeta^{rm ion}_{{rm H}_2}}$) is plagued by uncertainties in the adopted chemical networks and the analysis techniques. This work aims to homogeneously estimate the ${zeta^{rm ion}_{{rm H}_2}}$ at parsec scales towards the Orion Molecular Clouds OMC-2 and OMC-3, probing its variation across a whole star-forming region and a range of column densities never explored before. The mostRead More →

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A self-consistent model for dust settling and the vertical shear instability in protoplanetary disks Yuya Fukuhara, Satoshi Okuzumi arXiv:2404.15780v1 Announce Type: new Abstract: The spatial distribution of dust particles in protoplanetary disks affects dust evolution and planetesimal formation processes. The vertical shear instability (VSI) is one of the candidate hydrodynamic mechanisms that can generate turbulence in the outer disk region and affect dust diffusion. Turbulence driven by the VSI has a predominant vertical motion that can prevent dust settling. On the other hand, the dust distribution controls the spatial distribution of the gas cooling rate, thereby affecting the strength of VSI-driven turbulence. Here, we presentRead More →

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In: arXiv

Feature Selection Techniques for CR Isotope Identification with the AMS-02 Experiment in Space Marta Borchiellini, Leandro Mano, Fernando Bar~ao, Manuela Vecchi arXiv:2404.15783v1 Announce Type: new Abstract: Isotopic composition measurements of singly charged cosmic rays (CR) provide essential insights into CR transport in the Galaxy. The Alpha Magnetic Spectrometer (AMS-02) can identify singly charged isotopes up to about 10 GeV/n. However, their identification presents challenges due to the small abundance of CR deuterons compared to the proton background. In particular, a high accuracy for the velocity measured by a ring-imaging Cherenkov detector (RICH) is needed to achieve a good isotopic mass separation over a wide rangeRead More →

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A Hierarchical PSF Reconstruction Method Pedro Alonso, Jun Zhang, Cong Liu arXiv:2404.15795v1 Announce Type: new Abstract: Reconstruction of the point spread function (PSF) plays an important role in many areas of astronomy, including photometry, astrometry, galaxy morphology, and shear measurement. The atmospheric and instrumental effects are the two main contributors to the PSF, both of which may exhibit complex spatial features. Current PSF reconstruction schemes typically rely on individual exposures, and its ability of reproducing the complicated features of the PSF distribution is therefore limited by the number of stars. Interestingly, in conventional methods, after stacking the model residuals of the PSF ellipticities and (relative)Read More →

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JWST observations of the Horsehead photon-dominated region I. First results from multi-band near- and mid-infrared imaging A. Abergel, K. Misselt, K. D. Gordon, A. Noriega-Crespo, P. Guillard, D. Van De Putte, A. N. Witt, N. Ysard, M. Baes, H. Beuther, P. Bouchet, B. R. Brandl, M. Elyajouri, O. Kannavou, S. Kendrew, P. Klassen, B. Trahin arXiv:2404.15816v1 Announce Type: new Abstract: The JWST has captured the sharpest IR images ever taken of the Horsehead nebula, a prototypical moderately irradiated PDR that is fully representative of most of the UV-illuminated molecular gas in the Milky Way and star-forming galaxies. We investigate the impact of FUV radiation ofRead More →

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In: arXiv

Three-dimensional thermodynamic structures of the intracluster medium across edges in the X-ray surface brightness of massive, bright, dynamically-active galaxy clusters Shutaro Ueda, Yuto Ichinohe arXiv:2404.15824v1 Announce Type: new Abstract: We present a detailed study of three-dimensional (3D) thermodynamic structures of the intracluster medium (ICM) across edges in the X-ray surface brightness of four massive, bright, dynamically-active galaxy clusters (A3667, A2319, A520, and A2146), with the Chandra X-ray Observatory. Based on a forward modeling approach developed in previous work, we extend this approach with more generalized ICM density and temperature profiles, allowing us to apply uniformly to the observed X-ray surface brightness profiles to detect edgesRead More →

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In: arXiv

Hierarchical hub-filament structures and gas inflows on galaxy-cloud scales J. W. Zhou, Timothy A. Davis arXiv:2404.15862v1 Announce Type: new Abstract: We investigated the kinematics and dynamics of gas structures on galaxy-cloud scales in two spiral galaxies NGC5236 (M83) and NGC4321 (M100) using CO (2$-$1) line. We utilized the FILFINDER algorithm on integrated intensity maps for the identification of filaments in two galaxies. Clear fluctuations in velocity and density were observed along these filaments, enabling the fitting of velocity gradients around intensity peaks. The variations in velocity gradient across different scales suggest a gradual and consistent increase in velocity gradient from large to small scales, indicativeRead More →

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In: arXiv

Scattering Cross Sections of Magnetized Particles within Intense Electromagnetic Waves: Application to Fast Radio Bursts Yu-Chen Huang, Shu-Qing Zhong, Zi-Gao Dai arXiv:2404.15870v1 Announce Type: new Abstract: Recently, Beloborodov suggested that there exists a resonance phenomenon between an extremely intense electromagnetic wave and internal magnetized particles. The particles exchange energy with the wave at frequent resonance events and then reach the radiation reaction limit immediately. This process greatly enhances the scattering cross section of the particles. Note that these results only involve an extraordinary (X) mode wave. In this paper, we focus on an intense ordinary (O) mode wave propagating through magnetized particles and compare itRead More →

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In: arXiv

Quasi-equilibrium chemical evolution in starless cores Jonathan Rawlings, Eric Keto, Paola Caselli arXiv:2404.15876v1 Announce Type: new Abstract: The chemistry of H2O, CO and other small molecular species in an isolated pre-stellar core, L1544, has been assessed in the context of a comprehensive gas-grain chemical model, coupled to an empirically constrained physical/dynamical model. Our main findings are (i) that the chemical network remains in near equilibrium as the core evolves towards star formation and the molecular abundances change in response to the evolving physical conditions. The gas-phase abundances at any time can be calculated accurately with equilibrium chemistry, and the concept of chemical clocks is meaninglessRead More →

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In: arXiv

The Robotic MAAO 0.7m Telescope System: Performance and Standard Photometric System Gu Lim, Dohyeong Kim, Seonghun Lim, Myungshin Im, Hyeonho Choi, Jaemin Park, Keun-Hong Park, Junyeong Park, Chaudhary Muskaan, Donghyun Kim, Hayeong Jeong arXiv:2404.15884v1 Announce Type: new Abstract: We introduce a 0.7m telescope system at the Miryang Arirang Astronomical Observatory (MAAO), a public observatory in Miryang, Korea. System integration and a scheduling program enable the 0.7m telescope system to operate completely robotically during nighttime, eliminating the need for human intervention. Using the 0.7m telescope system, we obtain atmospheric extinction coefficients and the zero-point magnitudes by observing standard stars. As a result, we find that atmosphericRead More →

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Mapping the Milky Way’s Magnetic Field in 3D We are all very familiar with the concept of the Earth’s magnetic field. It turns out that most objects in space have magnetic fields but it’s quite tricky to measure them. Astronomers have developed an ingenious way to measure the magnetic field of the Milky Way using polarised light from interstellar dust grains that align themselves to the magnetic field lines. A new survey has begun this mapping process and has mapped an area that covers the equivalent of 15 times the full Moon.  Many people will remember experiments in school with iron filings and bar magnetsRead More →

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NASA’s New Solar Sail Has Launched and Deployed Solar Sails are an enigmatic and majestic way to travel across the gulf of space. Drawing an analogy to the sail ships of the past, they are one of the most efficient ways of propelling craft in space. On Tuesday a RocketLab Electron rocket launched NASA’s new Advanced Composite Solar Sail System. It aims to test the deployment of large solar sails in low-earth orbit and on Wednesday, NASA confirmed they had successfully deployed a 9 metre sail.  In 1886 the motor car was invented. In 1903 humans made their first powered flight. Just 58 years later,Read More →

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Here’s Why We Should Put a Gravitational Wave Observatory on the Moon Scientists detected the first long-predicted gravitational wave in 2015, and since then, researchers have been hungering for better detectors. But the Earth is warm and seismically noisy, and that will always limit the effectiveness of Earth-based detectors. Is the Moon the right place for a new gravitational wave observatory? It might be. Sending telescopes into space worked well, and mounting a GW observatory on the Moon might, too, though the proposal is obviously very complex. Most of astronomy is about light. The better we can sense it, the more we learn about nature.Read More →

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Recently discovered black hole is part of a nearby disrupted star cluster, study finds European astronomers have investigated a recently detected black hole designated Gaia BH3. In their results, they found that the black hole is associated with a nearby disrupted star cluster known as ED-2. The finding is reported in a paper published April 17 on the preprint server arXiv. phys.org Go to SourceRead More →

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TESS Finds its First Rogue Planet Well over 5,000 planets have been found orbiting other star systems. One of the satellites hunting for them is TESS, the Transiting Exoplanet Survey Satellite. Astronomers using TESS think they are made a rather surprising discovery; their first free-floating – or rogue – planet. The planet was discovered using gravitational microlensing where the planet passed in front of a star, distorting its light and revealing its presence. We are all familiar with the eight planets in our Solar System and perhaps becoming familiar with the concept of exoplanets. But there is another category of planet, the rogue planets. TheseRead More →

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NASA’s Chandra releases timelapse movies of Crab Nebula and Cassiopeia A New movies of two of the most famous objects in the sky—the Crab Nebula and Cassiopeia A—are being released from NASA’s Chandra X-ray Observatory. Each includes X-ray data collected by Chandra over about two decades. They show dramatic changes in the debris and radiation remaining after the explosion of two massive stars in our galaxy. phys.org Go to SourceRead More →

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There are Four Ways to Build with Regolith on the Moon Over the last few years I have been renovating my home. Building on Earth seems to be a fairly well understood process, after all we have many different materials to chose from. But what about future lunar explorers. As we head closer toward a permanent lunar base, astronauts will have very limited cargo carrying capability so will have to use local materials. On the Moon, that means relying upon the dusty lunar regolith that covers the surface. Researchers have now developed 20 different methods for creating building materials out of the stuff. They includeRead More →

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In: arXiv

Exploring Radio Emissions from Confirmed Exoplanets Using SKA Fatemeh Bagheri, Anshuman Garga, Ramon E. Lopez arXiv:2404.14468v1 Announce Type: new Abstract: Currently, our understanding of magnetic fields in exoplanets remains limited compared to those within our solar system. Planets with magnetic fields emit radio signals primarily due to the Electron Cyclotron Maser Instability mechanism. In this study, we explore the feasibility of detecting radio emissions from exoplanets using the Square Kilometre Array (SKA) radio telescope. Utilizing data from the NASA Exoplanet Archive, we compile information on confirmed exoplanets and estimate their radio emissions using the RBL model. Our analysis reveals that three exoplanets- Qatar-4 b, TOI-1278Read More →

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In: arXiv

Finding the unusual red giant remnants of cataclysmic variable mergers Nicholas Z. Rui, Jim Fuller arXiv:2404.14474v1 Announce Type: new Abstract: Mergers between helium white dwarfs and main-sequence stars are likely common, producing red giant-like remnants making up roughly a few percent of all low-mass ($lesssim2M_odot$) red giants. Through detailed modelling, we show that these merger remnants possess distinctive photometric, asteroseismic, and surface abundance signatures through which they may be identified. During hydrogen shell burning, merger remnants reach higher luminosities and possess pulsations which depart from the usual degenerate sequence on the asteroseismic $Deltanu$–$DeltaPi$ diagram for red giant branch stars. For sufficiently massive helium white dwarfs,Read More →

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JWST ERS Program Q3D: The pitfalls of virial BH mass constraints shown in a z = 3 quasar with an ultramassive host Caroline Bertemes, Dominika Wylezalek, David S. N. Rupke, Nadia L. Zakamska, Sylvain Veilleux, Benjamin Beckmann, Andrey Vayner, Swetha Sankar, Yuzo Ishikawa, Nadiia Diachenko, Weizhe Liu, Yu-Ching Chen, Jerome Seebeck, Dieter Lutz, Guilin Liu arXiv:2404.14475v1 Announce Type: new Abstract: We present JWST MIRI/NIRSpec observations of the extremely red quasar SDSS J165202.64+172852.3 at z~3, one of the most luminous quasars known to date, driving powerful outflows and hosting a clumpy starburst, amidst several interacting companions. We estimate the black hole (BH) mass of the systemRead More →