RAS_WEB (Page 39)

Wandering intermediate-mass black holes in Milky Way-sized galaxies in cosmological simulations: myth or reality? Floor van Donkelaar, Lucio Mayer, Pedro R. Capelo, Tomas Tamfal arXiv:2404.15404v1 Announce Type: new Abstract: In this work, we address the following question: “can we use the current cosmological simulations to identify intermediate-mass black holes (IMBHs) and quantify a putative population of wandering IMBHs?”. We compare wandering-IMBH counts in different simulations with different sub-grid methods and post-processing recipes, the ultimate goal being to aid future wandering-IMBH detection efforts. In particular, we examine simulations in which IMBHs are identified as BH seeds forming at high redshift and those in which they areRead More →

Photometry of Saturated Stars with Machine Learning Dominek Winecki (Dept. of Computer Science and Engineeering, The Ohio State University), Christopher S. Kochanek (Dept. of Astronomy, The Ohio State University) arXiv:2404.15405v1 Announce Type: new Abstract: We develop a deep neural network (DNN) to obtain photometry of saturated stars in the All-Sky Automated Survey for Supernovae (ASAS-SN). The DNN can obtain unbiased photometry for stars from g=4 to 14 mag with a dispersion (15%-85% 1sigma range around median) of 0.12 mag for saturated (garXiv:2404.15405v1 Announce Type: new Abstract: We develop a deep neural network (DNN) to obtain photometry of saturated stars in the All-Sky Automated Survey forRead More →

Stellar atmospheric parameters of $sim$ 11,000 RR Lyrae stars from LAMOST Spectra Jiangtao Wang, Jianrong Shi, Jianning Fu, Weikai Zong, Chunqian Li arXiv:2404.15411v1 Announce Type: new Abstract: Accurate determination of the stellar atmospheric parameters of RR Lyrae stars (RRLs) requires short individual exposures of the spectra to mitigate pulsation effects. We present improved template matching methods to determine the stellar atmospheric parameters of RRLs from single-epoch spectra of LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope, also known as the Guoshoujing telescope). We determine the radial velocities and stellar atmospheric parameters (effective temperature: $T_mathrm{eff}$, surface gravity: $log{g}$, and metallicity: [M/H]) of 10,486 and 1,027 RRLsRead More →

A Spatially Resolved [CII] Survey of 31 $zsim7$ Massive Galaxies Hosting Luminous Quasars Feige Wang, Jinyi Yang, Xiaohui Fan, Bram Venemans, Roberto Decarli, Eduardo Ba~nados, Fabian Walter, Aaron J. Barth, Fuyan Bian, Frederick B. Davies, Anna-Christina Eilers, Emanuele Paolo Farina, Joseph F. Hennawi, Jiang-Tao Li, Chiara Mazzucchelli, Ran Wang, Xue-Bing Wu, Minghao Yue arXiv:2404.15413v1 Announce Type: new Abstract: The [CII] 158 $mu$m emission line and the underlying far-infrared (FIR) dust continuum are important tracers for studying star formation and kinematic properties of early galaxies. We present a survey of the [CII] emission lines and FIR continua of 31 luminous quasars at $z>6.5$ using the AtacamaRead More →

Host Stars and How Their Compositions Influence Exoplanets Natalie R. Hinkel, Allison Youngblood, Melinda Soares-Furtado arXiv:2404.15422v1 Announce Type: new Abstract: It has become a common practice within the exoplanet field to say that “to know the star is to know the planet.” The properties of the host star have a strong, direct influence on the interior and surface conditions of the orbiting planet and oftentimes measurements of planetary properties are made relative to the star’s properties. Not only are observational measurements of the star necessary to determine even the most basic aspects of the planet (such as mass and radius), but the stellar environment influencesRead More →

Chemistry in Protoplanetary Disks Ke Zhang arXiv:2404.15423v1 Announce Type: new Abstract: Planets are formed inside disks around young stars. The gas, dust, and ice in these natal disks are the building materials of planets, and therefore their compositions fundamentally shape the final chemical compositions of planets. In this review, we summarize current observations of molecular lines in protoplanetary disks, from near-infrared to millimeter wavelengths. We discuss the basic types of chemical reactions in disks and the current development of chemical modeling. In particular, we highlight the progress made in understanding snowline locations, abundances of main carriers of carbon, oxygen, and nitrogen, and complex organic moleculesRead More →

Meteorites and Planet Formation Rhian H. Jones arXiv:2404.15424v1 Announce Type: new Abstract: Meteorites are a remarkable resource. They capture the imagination of people worldwide with their spectacular entry through Earth’s atmosphere as fireballs, and their exotic character of being pieces of other worlds. Scientifically, they are critical to interpreting the early stages of formation of the Solar System, as well as the geological evolution of asteroids, the Moon, and Mars, and they are vital to understanding planetary formation processes. With the burgeoning exploration of extrasolar planetary systems, knowledge of the fundamental process of planetary growth from protoplanetary disks has taken on a new significance. MeteoritesRead More →

The chemistry of extra-solar materials from white dwarf planetary systems Siyi Xu, Laura K. Rogers, Simon Blouin arXiv:2404.15425v1 Announce Type: new Abstract: White dwarf planetary systems provide a unique way to measure the bulk composition of exoplanetary material. Extrasolar asteroids/comets/moons which have survived the evolution of their host star can end up in the atmosphere of the white dwarf. Asteroids and boulders appear to be the most common pollutants, where we use the term “asteroids” to refer to the parent body that is polluting the atmosphere. The presence of the planetary material is detected via absorption lines of heavy elements. White dwarfs with these absorptionRead More →

Exoplanet Mineralogy Keith D. Putirka arXiv:2404.15426v1 Announce Type: new Abstract: This chapter begins with some basic concepts regarding the structure and mineralogy of rocky planets, how to read and construct ternary diagrams, and why partial melting occurs when plate tectonics is operative. Partial melting is a key concept in that it governs crust and core formation, which in turn control mineralogy. These sections are for astronomers, or geologists new to the study of igneous petrology. From there, computational approaches for estimating planetary mineral assemblages will be introduced. These quantitative methods are simple, consonant with the level of information currently available on exoplanet compositions, and whileRead More →

From stars to diverse mantles, melts, crusts and atmospheres of rocky exoplanets Claire Marie Guimond, Haiyang Wang, Fabian Seidler, Paolo Sossi, Aprajit Mahajan, Oliver Shorttle arXiv:2404.15427v1 Announce Type: new Abstract: This review is focused on describing the logic by which we make predictions of exoplanetary compositions and mineralogies, and how these processes could lead to compositional diversity among rocky exoplanets. We use these predictions to determine the sensitivity of present-day and future observations to detecting compositional differences between rocky exoplanets and the four terrestrial planets. First, we review data on stellar abundances and infer how changes in composition may manifest themselves in the expected bulkRead More →

Some Tectonic Concepts Relevant to the Study of Rocky Exoplanets Keith D. Putirka arXiv:2404.15428v1 Announce Type: new Abstract: We’ll examine plate tectonics on Earth — its features and forces — and examine some concepts that may allow astronomers to ask useful questions regarding numeric models that putatively predict tectonic activity. But exo-planetologists should be aware that geologists are still attempting to understand: why does Earth operates as it does, and so much differently than its neighbors? Has it always operated this way and have other planets of the inner Solar System ever mimicked Earth’s behavior in their past? These problems are unsolved, though some interestingRead More →

Exoplanet Magnetic Fields David A. Brain, Melodie M. Kao, Joseph G. O’Rourke arXiv:2404.15429v1 Announce Type: new Abstract: Planetary magnetic fields are important indicators of planetary processes and evolution, from a planet’s outer core to its surface (if it possesses one) to its atmosphere and near-space environment. Magnetic fields are most directly measured in situ, and determining whether distant planetary objects possess magnetic fields can be challenging. At present we have no unambiguous measurements of magnetic fields on exoplanets. Nevertheless, it would be surprising if at least some exoplanets did not generate a magnetic field, like many planetary bodies in the solar system. This chapter providesRead More →

Transiting Exoplanet Atmospheres in the Era of JWST Eliza M. -R. Kempton, Heather A. Knutson arXiv:2404.15430v1 Announce Type: new Abstract: The field of exoplanet atmospheric characterization has recently made considerable advances with the advent of high-resolution spectroscopy from large ground-based telescopes and the commissioning of the James Webb Space Telescope (JWST). We have entered an era in which atmospheric compositions, aerosol properties, thermal structures, mass loss, and three-dimensional effects can be reliably constrained. While the challenges of remote sensing techniques imply that individual exoplanet atmospheres will likely never be characterized to the degree of detail that is possible for solar system bodies, exoplanets present anRead More →

An Overview of Exoplanet Biosignatures Edward W. Schwieterman, Michaela Leung arXiv:2404.15431v1 Announce Type: new Abstract: This chapter reviews proposed exoplanet biosignatures, including their biological origins, observable features, atmospheric sinks, and potentially confounding abiotic sources. Emphasis is placed on material published since past comprehensive reviews while providing a foundational understanding of each named biosignature. Topics include possible gaseous biosignatures (e.g., O$_2$, O$_3$, CH$_4$, N$_2$O, DMS, CH$_3$Cl, C$_5$H$_8$, NH$_3$, PH$_3$), surface biosignatures (e.g., vegetation red edge, other pigment features, polarization signatures), and temporal biosignatures (e.g., atmospheric seasonality). Potential frameworks for assessing remote biosignatures are described. Text and table summaries provide references to relevant original research articles.arXiv:2404.15431v1 AnnounceRead More →

The early Earth as an analogue for exoplanetary biogeochemistry Eva E. St"ueken, Stephanie L. Olson, Eli Moore, Bradford J. Foley arXiv:2404.15432v1 Announce Type: new Abstract: Planet Earth has evolved from an entirely anoxic planet with possibly a different tectonic regime to the oxygenated world with horizontal plate tectonics that we know today. For most of this time, Earth has been inhabited by a purely microbial biosphere albeit with seemingly increasing complexity over time. A rich record of this geobiological evolution over most of Earth’s history provides insights into the remote detectability of microbial life under a variety of planetary conditions. We leverage Earth’s geobiological recordRead More →

Exoplanet Geology: What can we learn from current and future observations? Bradford J. Foley arXiv:2404.15433v1 Announce Type: new Abstract: Nearly 30 years after the discovery of the first exoplanet around a main sequence star, thousands of planets have now been confirmed. These discoveries have completely revolutionized our understanding of planetary systems, revealing types of planets that do not exist in our solar system but are common in extrasolar systems, and a wide range of system architectures. Our solar system is clearly not the default for planetary systems. The community is now moving beyond basic characterization of exoplanets (mass, radius, and orbits) towards a deeper characterizationRead More →

The Gravity Collective: A Comprehensive Analysis of the Electromagnetic Search for the Binary Neutron Star Merger GW190425 D. A. Coulter, C. D. Kilpatrick, D. O. Jones, R. J. Foley, A. V. Filippenko, W. Zheng, J. J. Swift, G. S. Rahman, H. E. Stacey, A. L. Piro, C. Rojas-Bravo, J. Anais Vilchez, N. Mu~noz-Elgueta, I. Arcavi, G. Dimitriadis, M. R. Siebert, J. S. Bloom, M. J. Bustamante-Rosell, K. E. Clever, K. W. Davis, J. Kutcka, P. Macias, P. McGill, P. J. Qui~nonez, E. Ramirez-Ruiz, K. Siellez, S. Tinyanont, S. B. Cenko, M. R. Drout, R. Hausen, W. V. Jacobson-Gal’an, D. Andrew Howell, D. Kasen, C. McCully,Read More →

Synthetic stellar spectra to study multiple populations in globular clusters: an extended grid and the effects on the integrated light Vinicius Branco (Universidade de S~ao Paulo IAG, Universit’e de Strasbourg CNRS Observatoire astronomique de Strasbourg), Paula R. T. Coelho (Universidade de S~ao Paulo IAG), Ariane Lanc{c}on (Universit’e de Strasbourg CNRS Observatoire astronomique de Strasbourg), Lucimara P. Martins (NAT Universidade Cidade de S~ao Paulo), Philippe Prugniel (Universit’e de Lyon LyonI CRAL-Observatoire de Lyon) arXiv:2404.15468v1 Announce Type: new Abstract: Most Galactic Globular Clusters (GCs) harbour multiple populations of stars (MPs), composed of at least two generations: the first characterized by a “standard” $alpha$-enhanced metal mixture, as observedRead More →

Pwyll and Manann’an Craters as a Laboratory for Constraining Irradiation Timescales on Europa M. Ryleigh Davis, Michael E. Brown arXiv:2404.15474v1 Announce Type: new Abstract: We examine high spatial resolution Galileo/NIMS observations of the young (~1 My – 20 My) impact features, Pwyll and Manann'{a}n craters, on Europa’s trailing hemisphere in an effort to constrain irradiation timescales. We characterize their composition using a linear spectral modeling analysis and find that both craters and their ejecta are depleted in hydrated sulfuric acid relative to nearby older terrain. This suggests that the radiolytic sulfur cycle has not yet had enough time to build up an equilibrium concentration ofRead More →

What drives the corpulence of galaxies? I. The formation of central compact dwarf galaxies in TNG50 Abhner P. De Almeida, Gary A. Mamon, Avishai Dekel, Gast~ao B. Lima Neto arXiv:2404.15482v1 Announce Type: new Abstract: Nearby dwarf galaxies display a variety of effective radii (sizes) at given stellar mass, suggesting different evolution scenarios according to their final “stellar” size. The TNG hydrodynamical simulations present a bimodality in the z = 0 size-mass relation (SMRz0) of dwarf galaxies, at $r_{1/2,star}$ ~ 450 pc. Using the TNG50 simulation, we explore the evolution of the most massive progenitors of dwarf galaxies (z=0 $log( M_star / mathrm{M}_odot)$ between 8.4 andRead More →