Results 31 to 40 of about 2,036 (233)

Chemical History of Molecules in Circumstellar Disks [PDF]

Proceedings of the International Astronomical Union, 2011
AbstractThe chemical composition of a protoplanetary disk is determined not only by in situ chemical processes during the disk phase, but also by the history of the gas and dust before it accreted from the natal envelope. In order to understand the disk's chemical composition at the time of planet formation, especially in the midplane, one has to go ...
Visser, R., Van Dishoeck, E., Doty, S.
openaire   +3 more sources

Satellites and Small Bodies With ALMA: Insights Into Solar System Formation and Evolution

AGU Advances, Volume 6, Issue 6, December 2025.
Abstract Our understanding of the formation and evolution of planetary systems has made major advances in the past decade. This progress has been driven in large part by the Atacama Large Millimeter/submillimeter Array (ALMA), which has given us an unprecedented view of solar system bodies themselves, and of the structure and chemistry of forming ...
Katherine de Kleer, Michael E. Brown, Martin Cordiner, Richard Teague   +3 more
wiley   +1 more source

JWST Imaging of the Closest Globular Clusters—VI. The Lowest‐Mass Objects in M 4 and the Galactic Bulge

Astronomische Nachrichten, Volume 346, Issue 9, November 2025.
ABSTRACT We present James Webb Space Telescope observations of M 4—the closest globular cluster—that probe the lower Main Sequence down to the hydrogen‐burning limit. The unveiled stellar sequence reaches much fainter luminosities than previously possible, revealing a few extremely red objects that are consistent with brown dwarfs as cool as Teff∼1000K$
L. R. Bedin, R. Gerasimov, A. Calamida, M. Libralato, M. Scalco, D. Nardiello, M. Griggio, D. Apai, J. Anderson, A. Bellini, A. Burgasser   +10 more
wiley   +1 more source

Angular Momentum Transport in Binary Star Formation: The Enhancement of Magnetorotational Instability and Role of Outflows

The Astrophysical Journal
The formation of binary stars is highly influenced by magnetic fields, which play a crucial role in transporting angular momentum. We conducted 3D numerical simulations of binary star accretion via a circumbinary disk, taking into account a magnetic ...
Tomoaki Matsumoto
doaj   +1 more source

Revisiting the Chemical Composition of WD 1145+017: Impact of Circumstellar Disk Contamination on Photospheric Abundances

The Astrophysical Journal
We performed a chemical analysis of the asteroid-bearing white dwarf WD 1145+017 using optical and ultraviolet spectroscopic data from 25 epochs between 2015 and 2023.
Érika Le Bourdais, Patrick Dufour, Siyi Xu   +2 more
doaj   +1 more source

JWST Imaging of the Closest Globular Clusters—V. The White Dwarfs Cooling Sequence of M4

Astronomische Nachrichten, Volume 346, Issue 2, February 2025.
ABSTRACT We combine infrared (IR) observations collected by the James Webb Space Telescope with optical deep images by the Hubble Space Telescope taken ~20 years earlier to compute proper‐motion membership for the globular cluster (GC) M4 (NGC 6121) along its entire white dwarf (WD) cooling sequence (CS).
Luigi R. Bedin, Mattia Libralato, Maurizio Salaris, Domenico Nardiello, Michele Scalco, Massimo Griggio, Jay Anderson, Pierre Bergeron, Andrea Bellini, Roman Gerasimov, Adam J. Burgasser, Daniel Apai   +11 more
wiley   +1 more source

Debris Disks Can Contaminate Mid-infrared Exoplanet Spectra: Evidence for a Circumstellar Debris Disk around Exoplanet Host WASP-39

The Astrophysical Journal Letters
The signal from a transiting planet can be diluted by astrophysical contamination. In the case of circumstellar debris disks, this contamination could start in the mid-infrared and vary as a function of wavelength, which would then change the observed ...
Laura Flagg, Alycia J. Weinberger, Taylor J. Bell, Luis Welbanks, Giuseppe Morello, Diana Powell, Jacob L. Bean, Jasmina Blecic, Nicolas Crouzet, Peter Gao, Julie Inglis, James Kirk, Mercedes López-Morales, Karan Molaverdikhani, Nikolay Nikolov, Apurva V. Oza, Benjamin V. Rackham, Seth Redfield, Shang-Min Tsai, Ray Jayawardhana, Laura Kreidberg, Matthew C. Nixon, Kevin B. Stevenson, Jake D. Turner   +23 more
doaj   +1 more source

A Study of ISO Spectra for Herbig Ae/Be Stars [PDF]

Journal of Astronomy and Space Sciences, 2002
We present the infrared spectra of Herbig Ae/Be stars including the Infrared Space Observatory (ISO) data. To investigate the overall properties of their circumstellar dust envelope and/or disk, we combine the IR spectra with photometric data ranging ...
Kyung-Won Suh, Mi-Ryang Kim, Ji-Hye Baek
doaj   +1 more source

Black Hole Hyperaccretion in Collapsars: A Review

Universe, 2022
The collapsar model is widely accepted as one of the standard scenarios for gamma-ray bursts (GRBs). In the massive collapsar scenario, the core will collapse to a black hole (BH) surrounded by a temporary hyperaccretion disk with a very high accretion ...
Yun-Feng Wei, Tong Liu
doaj   +1 more source

Circumstellar Disks and Star Formation [PDF]

Highlights of Astronomy, 1992
Results from the IRAS satellite showed that many pre-main sequence stars exhibited unexpectedly large fluxes in the infrared spectral region. Several studies have shown that the simplest and most satisfying explanation of this excess emission is that it arises in optically-thick, dusty, circumstellar disks (Rucinski 1985; Adams, Lada, and Shu 1987 ...
L. Hartmann, M. Gomez, S.J. Kenyon
openaire   +1 more source