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How Did Pluto Get Its Heart? Scientists Suggest an Answer The most recognizable feature on Pluto is its “heart,” a relatively bright valentine-shaped area known as Tombaugh Regio. How that heart got started is one of the dwarf planet’s deepest mysteries — but now researchers say they’ve come up with the most likely scenario, involving a primordial collision with a planetary body that was a little more than 400 miles wide. The scientific term for what happened, according to a study published today in Nature Astronomy, is “splat.” Astronomers from the University of Bern in Switzerland and the University of Arizona looked for computer simulationsRead More →

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The Milky Way’s Role in Ancient Egyptian Mythology Look through the names and origins of the constellations and you will soon realise that many cultures had a hand in their conceptualisation. Among them are the Egyptians who were fantastic astronomers. The movement of the sky played a vital role in ancient Egypt including the development of the 365 day year and the 24 hour day. Like many other cultures they say the Sun, Moon and planets as gods. Surprisingly though, the bright Milky Way seems not to have played a vital role. Some new research suggests that this may not be the case and itRead More →

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Rubin observatory will reveal dark matter’s ghostly disruptions of stellar streams Glittering threads of stars around the Milky Way may hold answers to one of our biggest questions about the universe: what is dark matter? With images taken through six different color filters mounted to the largest camera ever built for astronomy and astrophysics, Vera C. Rubin Observatory’s upcoming Legacy Survey of Space and Time will reveal never-before-seen stellar streams around the Milky Way—and the telltale effects of their interactions with dark matter. phys.org Go to SourceRead More →

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You Can’t Know the True Size of an Exoplanet Without Knowing its Star’s Magnetic Field In 2011, astronomers with the Wide Angle Search for Planets (WASP) consortium detected a gas giant orbiting very close to a Sun-like (G-type) star about 700 light-years away. This planet is known as WASP-39b (aka. “Bocaprins”), one of many “hot Jupiters” discovered in recent decades that orbits its star at a distance of less than 5% the distance between the Earth and the Sun (0.05 AU). In 2022, shortly after the James Webb Space Telescope (JWST) it became the first exoplanet to have carbon dioxide and sulfur dioxide detected inRead More →

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In: arXiv

Imaging dark matter at the smallest scales with lensed stars J. M. Diego, Sung Kei Li, Alfred Amruth, Ashish K. Meena, Tom J. Broadhurst, Patrick L. Kelly, Alexei V. Filippenko, Liliya L. R. Williams, Adi Zitrin, William E. Harris, Marta Reina-Campos, Carlo Giocoli, Liang Dai, Mitchell F. Struble, Tommaso Treu, Yoshinobu Fudamoto, Daniel Gilman, Anton M. Koekemoer, Jeremy Lim, J. M. Palencia, Fengwu Sun, Rogier A. Windhorst arXiv:2404.08033v1 Announce Type: new Abstract: Observations of caustic-crossing galaxies at redshift $0.72$ and the number density of events is greater around substructureand the number density of events is greater around substructures, and (ii) negative imaging regime where $betaarXiv:2404.08033v1Read More →

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Solar photospheric spectrum microvariability II. Observed relations to magnetic activity and radial-velocity modulation Dainis Dravins, Hans-G"unter Ludwig arXiv:2404.08035v1 Announce Type: new Abstract: Searches for small exoplanets around solar-type stars are limited by stellar physical variability. While chromospheric variability is well studied, observing, modeling. and understanding the much smaller fluctuations in photospheric spectral line strengths, shapes, and shifts is challenging. Extreme precision radial-velocity spectrometers now enable extreme precision stellar spectroscopy and time series of the Sun seen as a star permit monitoring of its photospheric variability. Fluctuations in their line strengths may well correlate with radial-velocity excursions and identify observable proxies for their monitoring. From threeRead More →

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Euclid preparation. XLII. A unified catalogue-level reanalysis of weak lensing by galaxy clusters in five imaging surveys Euclid Collaboration, M. Sereno (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Bologna, Italy, INFN-Sezione di Bologna, Bologna, Italy), S. Farrens (Universit’e Paris-Saclay, Universit’e Paris Cit’e, CEA, CNRS, AIM, Gif-sur-Yvette, France), L. Ingoglia (Dipartimento di Fisica e Astronomia "Augusto Righi" – Alma Mater Studiorum Universit`a di Bologna, Bologna, Italy), G. F. Lesci (Dipartimento di Fisica e Astronomia "Augusto Righi" – Alma Mater Studiorum Universit`a di Bologna, Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Bologna, Italy), L. Baumont (AIM, CEA, CNRS, Universit’e Paris-Saclay, Universit’eRead More →

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The Evolution of Binaries Embedded Within Common Envelopes Alejandra Rosselli-Calderon, Ricardo Yarza, Ariadna Murguia-Berthier, Valeriia Rohoza, Rosa Wallace Everson, Andrea Antoni, Morgan MacLeod, Enrico Ramirez-Ruiz arXiv:2404.08037v1 Announce Type: new Abstract: Triple stellar systems allow us to study stellar processes that cannot be attained in binary stars. The evolutionary phases in which the stellar members undergo mass exchanges can alter the hierarchical layout of these systems. Yet, the lack of a self-consistent treatment of common-envelope (CE) in triple star-systems hinders the comprehensive understanding of their long-term fate. This letter examines the conditions predicted around binaries embedded within CEs using local 3D hydrodynamical simulations. We explore varyingRead More →

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Small Magellanic Cloud Cepheids Observed with the Hubble Space Telescope Provide a New Anchor for the SH0ES Distance Ladder Louise Breuval, Adam G. Riess, Stefano Casertano, Wenlong Yuan, Lucas M. Macri, Martino Romaniello, Yukei S. Murakami, Daniel Scolnic, Gagandeep S. Anand, Igor Soszy’nski arXiv:2404.08038v1 Announce Type: new Abstract: We present photometric measurements of 88 Cepheid variables in the core of the Small Magellanic Cloud (SMC), the first sample obtained with the Hubble Space Telescope (HST) and Wide Field Camera 3, in the same homogeneous photometric system as past measurements of all Cepheids on the SH0ES distance ladder. We limit the sample to the inner coreRead More →

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Improving Photometric Galaxy Clustering Constraints With Cross-Bin Correlations Jordan Krywonos, Jessica Muir, Matthew C. Johnson arXiv:2404.08039v1 Announce Type: new Abstract: Clustering studies in current photometric galaxy surveys focus solely on auto-correlations, neglecting cross-correlations between redshift bins. We evaluate the potential advantages and drawbacks of incorporating cross-bin correlations in Fisher forecasts for the Dark Energy Survey (DES) and the forthcoming Rubin Observatory Legacy Survey of Space and Time (LSST). Our analysis considers the impact of including redshift space distortions (RSD) and magnification in model predictions, as well as systematic uncertainties in photometric redshift distributions (photo-$z$). While auto-correlations alone suffer from a degeneracy between the amplitude ofRead More →

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Three-Body Binary Formation in Clusters: Analytical Theory Yonadav Barry Ginat, Hagai B. Perets arXiv:2404.08040v1 Announce Type: new Abstract: Binary formation in clusters through triple encounters between three unbound stars, ‘three-body’ binary formation, is one of the main dynamical formation processes of binary systems in dense environments. In this paper, we use an analytical probabilistic approach to study the process for the equal mass case and calculate a probability distribution for the orbital parameters of three-body-formed binaries, as well as their formation rate. For the first time, we give closed-form analytical expressions to the full orbital parameter distribution, accounting for both energy and angular momentum conservation.Read More →

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Modeling Ionized Gas in the Small Magellanic Cloud: The Wolf-Rayet Nebula N76 Elizabeth Tarantino, Alberto D. Bolatto, R’emy Indebetouw, M’onica Rubio, Karin M. Sandstrom, J. -D T. Smith, Daniel Stapleton, Mark Wolfire arXiv:2404.08041v1 Announce Type: new Abstract: We present Cloudy modeling of infrared emission lines in the Wolf-Rayet (WR) nebula N76 caused by one of the most luminous and hottest WR stars in the low metallicity Small Magellanic Cloud. We use spatially resolved mid-infrared Spitzer/IRS and far-infrared Herschel/PACS spectroscopy to establish the physical conditions of the ionized gas. The spatially resolved distribution of the emission allows us to constrain properties much more accurately than usingRead More →

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In: arXiv

Testing common approximations to predict the 21cm signal at the Epoch of Reionization and Cosmic Dawn Timoth’ee Schaeffer, Sambit K. Giri, Aurel Schneider arXiv:2404.08042v1 Announce Type: new Abstract: Predicting the 21cm signal from the epoch of reionization and cosmic dawn is a complex and challenging task. Various simplifying assumptions have been applied over the last decades to make the modeling more affordable. In this paper, we investigate the validity of several such assumptions, using a simulation suite consisting of three different astrophysical source models that agree with the current constraints on the reionization history and the UV luminosity function. We first show that the commonRead More →

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Milky Way-est: Cosmological Zoom-in Simulations with Large Magellanic Cloud and Gaia-Sausage-Enceladus Analogs Deveshi Buch, Ethan O. Nadler, Risa H. Wechsler, Yao-Yuan Mao arXiv:2404.08043v1 Announce Type: new Abstract: We present Milky Way-est, a suite of 20 cosmological cold-dark-matter-only zoom-in simulations of Milky Way (MW)-like host halos. Milky Way-est hosts are selected such that they: ($i$) are consistent with the MW’s measured halo mass and concentration, ($ii$) accrete a Large Magellanic Cloud (LMC)-like ($approx 10^{11}~M_{odot}$) subhalo within the last $1.3~mathrm{Gyr}$ on a realistic orbit, placing them near $50~mathrm{kpc}$ from the host center at $zapprox 0$, and ($iii$) undergo a $>$1:5 sub-to-host halo mass ratio merger with aRead More →

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JWST Discovery of $40+$ Microlensed Stars in a Magnified Galaxy, the “Dragon” behind Abell 370 Yoshinobu Fudamoto, Fengwu Sun, Jose M. Diego, Liang Dai, Masamune Oguri, Adi Zitrin, Erik Zackrisson, Mathilde Jauzac, David J. Lagattuta, Eiichi Egami, Edoardo Iani, Rogier A. Windhorst, Katsuya T. Abe, Franz Erik Bauer, Fuyan Bian, Rachana Bhatawdekar, Thomas J. Broadhurst, Zheng Cai, Chian-Chou Chen, Wenlei Chen, Seth H. Cohen, Christopher J. Conselice, Daniel Espada, Nicholas Foo, Brenda L. Frye, Seiji Fujimoto, Lukas J. Furtak, Miriam Golubchik, Tiger Yu-Yang Hsiao, Jean-Baptiste Jolly, Hiroki Kawai, Patrick L. Kelly, Anton M. Koekemoer, Kotaro Kohno, Vasily Kokorev, Mingyu Li, Zihao Li, Xiaojing Lin, GeorgiosRead More →

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FORGE’d in FIRE III: The IMF in Quasar Accretion Disks from STARFORGE Philip F. Hopkins, Michael Y. Grudic, Kyle Kremer, Stella S. R. Offner, David Guszejnov, Anna L. Rosen arXiv:2404.08046v1 Announce Type: new Abstract: Recently, we demonstrated self-consistent formation of strongly-magnetized quasar accretion disks (QADs) from cosmological radiation-magnetohydrodynamic-thermochemical galaxy-star formation simulations, including the full STARFORGE physics shown previously to produce a reasonable IMF under typical ISM conditions. Here we study star formation and the stellar IMF in QADs, on scales from 100 au to 10 pc from the SMBH. We show it is critical to include physics often previously neglected, including magnetic fields, radiation, andRead More →

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The Origin of Young Stellar Populations in NGC 1783: Accretion of External Stars Li Wang, Licai Deng, Xiaoying Pang, Long Wang, Richard de Grijs, Antonino P. Milone, Chengyuan Li arXiv:2404.08047v1 Announce Type: new Abstract: The presence of young stellar populations in the Large Magellanic Cloud cluster NGC 1783 has caught significant attention, with suggestions ranging from it being a genuine secondary stellar generation to a population of blue straggler stars or simply contamination from background stars. Thanks to multi-epoch observations with the Hubble Space Telescope, proper motions for stars within the field of NGC 1783 have been derived, thus allowing accurate cluster membership determination. Here,Read More →

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The origin of the coherent radio flash potentially associated with GRB 201006A Nikhil Sarin, Teagan A. Clarke, Spencer J. Magnall, Paul D. Lasky, Brian D. Metzger, Edo Berger, Navin Sridhar arXiv:2404.08048v1 Announce Type: new Abstract: Rowlinson et al. 2023 recently claimed the detection of a coherent radio flash 76.6 minutes after a short gamma-ray burst. They proposed that the radio emission may be associated with a long-lived neutron star engine. We show through theoretical and observational arguments that the coherent radio emission, if real and indeed associated with GRB 201006A and at the estimated redshift, is unlikely to be due to the collapse of theRead More →

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In: arXiv

Observational Tests of Active Galactic Nuclei Feedback: An Overview of Approaches and Interpretation Chris M. Harrison, Cristina Ramos Almeida arXiv:2404.08050v1 Announce Type: new Abstract: Growing supermassive black holes (Active Galactic Nuclei; AGN) release energy with the potential to alter their host galaxies and larger-scale environment; a process named “AGN feedback”. Feedback is a required component of galaxy formation models and simulations to explain observed properties of galaxy populations. We provide a broad overview of observational approaches that are designed to establish the physical processes that couple AGN energy to the multi-phase gas, or to find evidence that AGN impact upon galaxy evolution. The orders-of-magnitude rangeRead More →

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In: arXiv

Thermal Structure and Millimeter Emission of Protoplanetary Disk with embedded protoplanets from radiative transfer modeling Felipe Alarc’on, Edwin Bergin arXiv:2404.08051v1 Announce Type: new Abstract: The discovery of protoplanets and circumplanetary disks provides a unique opportunity to characterize planet formation through observations. Massive protoplanets shape the physical and chemical structure of their host circumstellar disk by accretion, localized emission, and disk depletion. In this work, we study the thermal changes induced within the disk by protoplanet accretion and synthetic predictions through hydrodynamical simulations with post-processed radiative transfer with an emphasis on radio millimeter emission. We explored distinct growth conditions and varied both planetary accretion rates andRead More →