Novel calculations peg age of ‘baby’ asteroid An asteroid dubbed “Lucy’s baby” after a NASA spacecraft discovered it is orbiting another asteroid last November is,, in fact,, a solar system toddler—just 2–3 million years old, a Cornell-led research team estimates using novel statistical calculations. phys.org Go to SourceRead More →
Clouds blanket the night side of the hot exoplanet WASP-43b Using the James Webb Space Telescope (JWST), a team of astronomers, including scientists from MPIA, constructed a global temperature map of the hot, gas giant exoplanet WASP-43b. The nearby parent star perpetually illuminates one hemisphere, raising temperatures to a blistering 1250°C. Meanwhile, eternal night shrouds the opposite side. phys.org Go to SourceRead More →
Researchers explore an old galactic open cluster Using data from ESA’s Gaia satellite, astronomers from Turkey and India have investigated NGC 188—an old open cluster in the Milky Way. Results of the study, published April 19 on the pre-print server arXiv, deliver important insights into the parameters and properties of this cluster. phys.org Go to SourceRead More →
Astronomers’ simulations support dark matter theory Computer simulations by astronomers support the idea that dark matter—matter that no one has yet directly detected but which many physicists think must be there to explain several aspects of the observable universe—exists, according to the researchers, who include those at the University of California, Irvine. phys.org Go to SourceRead More →
First Light from Einstein Probe: A Supernova Remnant On 9 January 2024, the Einstein probe was launched, its mission to study the night sky in X-rays. The first image from the probe that explores the Universe in these energetic wavelengths has just been released. It shows Puppis A, the supernova remnant from a massive star that exploded 4,000 years ago. The image showed the expanding cloud of ejecta from the explosion but now, Einstein will continue to scan the skies for other X-ray events. The Chinese and European probe was designed to revolutionise our understanding of the Universe in X-rays. Named after none other thanRead More →
Galaxies Evolved Surprisingly Quickly in the Early Universe Anyone familiar with astronomy will know that galaxies come in a fairly limited range of shapes, typically; spiral, elliptical, barred-spiral and irregular. The barred-spiral galaxy has been known to be a feature of the modern universe but a study from astronomers using the Hubble Space Telescope has recently challenged that view. Following on observations using the James Webb Space Telescope has found the bar feature in some spiral galaxies as early as 11 billion years ago suggesting galaxies evolved faster in the early Universe than previously expected. Our own Galaxy, the Milky Way is a spiral galaxyRead More →
How Knot Theory Can Help Spacecraft Can Change Orbits Without Using Fuel When a spacecraft arrives at its destination, it settles into an orbit for science operations. But after the primary mission is complete, there might be other interesting orbits where scientists would like to explore. Maneuvering to a different orbit requires fuel, limiting a spacecraft’s number of maneuvers. Researchers have discovered that some orbital paths allow for no-fuel orbital changes. But the figuring out these paths also are computationally expensive. Knot theory has been shown to find these pathways more easily, allowing the most fuel-efficient routes to be plotted. This is similar to howRead More →
Q&A: How to catch a glimpse of a new star about to appear in the night sky If you peer up at the constellation Corona Borealis—the Northern Crown—over the next several months, you may catch a glimpse: Astronomers predict that sometime this year, a new star will appear in the night sky, growing as bright as the North Star, then vanishing in a matter of days. phys.org Go to SourceRead More →
Another New Molecule Discovered Forming in Space The list of chemicals found in space is growing longer and longer. Astronomers have found amino acids and other building blocks of life on comets, asteroids, and even floating freely in space. Now, researchers have found another complex chemical to add to the list. The new chemical is known as 2-methoxyethanol (CH3OCH2CH2OH). It’s one of several methoxy molecules that scientists have found in space. But with 13 atoms, it’s one of the largest and most complex ones ever detected. A team of scientists called the McGuire Group specializes in detecting chemicals in space. The McGuire Group and otherRead More →
JWST Uses “Interferometry Mode” to Reveal Two Protoplanets Around a Young Star The JWST is flexing its muscles with its interferometry mode. Researchers used it to study a well-known extrasolar system called PDS 70. The goal? To test the interferometry mode and see how it performs when observing a complex target. The mode uses the telescope’s NIRISS (Near Infrared Imager and Slitless Spectrograph) as an interferometer. It’s called Aperture Masking Interferometry (AMI) and it allows the JWST to reach its highest level of spatial resolution. A team of astronomers used the JWST’s AMI to observe the PDS 70 system. PDS 70 is a young T-TauriRead More →
A Cold Brown Dwarf is Belching Methane Into Space Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with surface temperatures similar to Jupiter. The largest brown dwarfs have surface temperaturesRead More →
Measuring Exoplanetary Magnetospheres with the Square Kilometer Array Life on Earth would not be possible without food, water, light, a breathable atmosphere and surprisingly, a magnetic field. Without it, Earth, and its inhabitants would be subjected to the harmful radiation from space making life here, impossible. If we find exoplanets with similar magnetospheres then those worlds may well be habitable. The Square Kilometer Array (SKA) which is still under construction should be able to detect such magnetospheres from radio emissions giving us real insight into our exoplanet cousins. The magnetic field of Earth is the result of churning motion of liquid iron and nickel inRead More →
A compilation of solar atlases (from Delbouille, Kurucz, Gandorfer, Stenflo) at disk centre and at limb from $lambda$ 3000 {AA} to $lambda$ 8800 {AA} Jean-Marie Malherbe arXiv:2404.16902v1 Announce Type: new Abstract: We present in this paper a compilation of solar atlases from $lambda$ 3000 {AA} to $lambda$ 8800 {AA} with spectral lines identified by the Moore table and with the corresponding equivalent Lande factors g*. We used two spectra at disk centre ($mu$ = 1.0), from Delbouille and Kurucz, and two spectra at the limb from Stenflo and Gandorfer, respectively at $mu$ = 0.145 and $mu$ = 0.10.arXiv:2404.16902v1 Announce Type: new Abstract: We present inRead More →
Fine structure in the Sigma Orionis cluster revealed by Gaia DR3 M. v{Z}erjal (Instituto de Astrof’isica de Canarias, Universidad de La Laguna), E. L. Mart’in (Instituto de Astrof’isica de Canarias, Universidad de La Laguna), A. P’erez-Garrido (Universidad Polit’ecnica de Cartagena) arXiv:2404.16923v1 Announce Type: new Abstract: Sigma Orionis is an open cluster in the nearest giant star formation site – Orion. Its youth (3-5 Myr), low reddening, and relative vicinity make it an important benchmark cluster to study stellar and substellar formation and evolution. Young star-forming sites are complex and hierarchical. Precision astrometry from Gaia DR3 enables the exploration of their fine structure. We used theRead More →
Observational predictions for the survival of atomic hydrogen in simulated Fornax-like galaxy clusters Avinash Chaturvedi, Stephanie Tonnesen, Greg L. Bryan, Gerg"o Popping, Michael Hilker, Paolo Serra, Shy Genel arXiv:2404.16926v1 Announce Type: new Abstract: The presence of dense, neutral hydrogen clouds in the hot, diffuse intra-group and intra-cluster medium is an important clue to the physical processes controlling the survival of cold gas and sheds light on cosmological baryon flows in massive halos. Advances in numerical modeling and observational surveys means that theory and observational comparisons are now possible. In this paper, we use the high-resolution TNG50 cosmological simulation to study the HI distribution in sevenRead More →
Notes on the Practical Application of Nested Sampling: MultiNest, (Non)convergence, and Rectification Alexander J. Dittmann arXiv:2404.16928v1 Announce Type: new Abstract: Nested sampling is a promising tool for Bayesian statistical analysis because it simultaneously performs parameter estimation and facilitates model comparison. MultiNest is one of the most popular nested sampling implementations, and has been applied to a wide variety of problems in the physical sciences. However, MultiNest results are frequently unreliable, and accompanying convergence tests are a necessary component of any analysis. Using simple, analytically tractable test problems, I illustrate how MultiNest (1) can produce systematically biased estimates of the Bayesian evidence, which are more significantlyRead More →
The Renormalization Group for Large-Scale Structure: Origin of Galaxy Stochasticity Henrique Rubira, Fabian Schmidt arXiv:2404.16929v1 Announce Type: new Abstract: The renormalization group equations for large-scale structure (RG-LSS) describe how the bias and stochastic (noise) parameters — both of matter and biased tracers such as galaxies — evolve as a function of the cutoff $Lambda$ of the effective field theory. In previous work, we derived the RG-LSS equations for the bias parameters using the Wilson-Polchinski framework. Here, we extend these results to include stochastic contributions, corresponding to terms in the effective action that are higher order in the current $J$. We show that the RG equationsRead More →
Quick recipes for gravitational-wave selection effects Davide Gerosa, Malvina Bellotti arXiv:2404.16930v1 Announce Type: new Abstract: Accurate modeling of selection effects is a key ingredient to the success of gravitational-wave astronomy. The detection probability plays a crucial role in both statistical population studies, where it enters the hierarchical Bayesian likelihood, and astrophysical modeling, where it is used to convert predictions from population-synthesis codes into observable distributions. We review the most commonly used approximations, extend them, and present some recipes for a straightforward implementation. These include a closed-form expression capturing both multiple detectors and noise realizations written in terms of the so-called Marcum Q-function and a ready-to-useRead More →
IRX-CIGALE: a tailored module for Low-Luminosity AGN I. E. L’opez, G. Yang, G. Mountrichas, M. Brusa, D. M. Alexander, R. D. Baldi, E. Bertola, S. Bonoli, A. Comastri, F. Shankar, N. Acharya, A. V. Alonso Tetilla, A. Lapi, B. Laloux, X. L’opez L’opez, I. Mu~noz Rodr’iguez, B. Musiimenta, N. Osorio Clavijo, L. Sala, D. Sengupta arXiv:2404.16938v1 Announce Type: new Abstract: The spectral energy distribution (SED) of low-luminosity active galactic nuclei (LLAGN) presents unique challenges due to their comparable radiation output to their host galaxies and complex accretion dynamics. We introduce a novel module within the CIGALE framework specifically designed for SED fitting of LLAGN, incorporatingRead More →
On the mass assembly history of the Milky Way: clues from its stellar halo Danny Horta, Ricardo P. Schiavon arXiv:2404.16939v1 Announce Type: new Abstract: Stellar halos of galaxies retain crucial clues to their mass assembly history. It is in these galactic components that the remains of cannibalised galactic building blocks are deposited. For the case of the Milky Way, the opportunity to analyse the stellar halo’s structure on a star-by-star basis in a multi-faceted approach provides a basis from which to infer its past and assembly history in unrivalled detail. Moreover, the insights that can be gained about the formation of the Galaxy not onlyRead More →
