circumstellar disk Archives

Transition between different accretion regimes as shown by the shading and top labels. From left to right the panels show central AGN masses of 109, 108 and 107 𝑀⊙. The top row shows 𝑣frag = 1m s−1 and the bottom row shows 𝑣frag = 10 m−1 . The symbol 𝑚p gives the characteristic planetesimal mass, 𝑀HB is the transition mass between the Hill and the Bondi accretion regime, 𝑀BG is the transition mass between the Bondi and the geometric accretion regimes, and 𝑀p,iso is the pebble isolation mass. The transition between 2D and 3D accretion is also shown. In general, the objects will accrete in the 3D regime right after formation, except in the 1–10 pc range in the case 𝑣frag = 10 m/s, 𝑀SMBH = 109 𝑀⊙ (lower left). Accretion is also more efficient in the inner disk than in the outer disk, with a progression from Hill, Hill/Bondi, Bondi, and Bondi/Geometric as the central mass object decreases. The horizontal dotted black line is the hydrogen burning limit. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Exoplanets, -moons, -comets, Status Report

Active Galactic Nucleus Tori: Potential Birthplace to Millions of Planets

by Keith CowingMay 23, 2026May 23, 2026

The outer regions of AGN disks have temperatures similar to those of circumstellar disks, permitting dust condensation. Therefore, planet formation and growth could be active in these dust tori through […]

Comparison of host star masses and metallicities of N ≥3 categories of exoplanet systems (black points), compared with two of our potential source populations: all exoplanet hosts with jupiters (red) and all host stars without jupiters (blue). -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography

Architectures Of Planetary Systems II: Trends With Host Star Mass And Metallicity

by Keith CowingFebruary 8, 2026February 8, 2026

The current census of planetary systems displays a wide range of architectures. Extending earlier work, this paper investigates the correlation between our classification framework for these architectures and host stellar […]

(A) Spectral variation of the benzene:CO mixture before and after photon exposure. The dark blue line corresponds to the IR spectra before photon exposure, and the lighter blue corresponds to the IR spectra of the benzene:CO ice after photon exposure. (B) Spectral variation of the main aromatic bands as a function of photon fluence, with lighter colors representing higher photon fluence. Different colors are used to identify benzene, toluene, and benzonitrile. Each ice was exposed to approximately the same photon fluence of ∼7 × 1017 photons cm−2 (Table 2). Unless explicitly indicated, all subpanels share the same axis scale. -- astro-ph.IM

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report

The Survival Of Aromatic Molecules In Protoplanetary Disks

by Keith CowingOctober 16, 2025June 10, 2026

Aromaticity is a common chemical functionalities in bioactive molecules. In interstellar and circumstellar environments benzene and other small aromatics are considered the precursor for more complex prebiotic molecules and they […]

Zoomed-in maps of the system at t = tff+10 kyr (top) and t = tff + 150 kyr (bottom). The colors represent the number density of the gas, while the white lines indicate the iso-contours of the temperature at T= 50, 75, 100, and 300 K. -- astro-ph.GA

Astrochemistry, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Status Report, Stellar Cartography

The Evolution Of Complex Organic Molecules During Star Formation

by Keith CowingSeptember 19, 2025September 19, 2025

Complex organic molecules (COMs) are thought to be the precursors of pre-biotic molecules and are observed in many protostellar sources.

The circumstellar disk candidate in optical (left) from the Rubin Observatory “First Look” image and in infrared (right) from the Spitzer IRAC Healpix survey. Both images are 40″ on a side. North is up, east is left. -- AAS

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Possible Proplyd Disk Discovered In Rubin Observatory’s First-Look Image

by Keith CowingJuly 17, 2025

On 23 June 2025, the public got its first look at images from the NSF–DOE Vera C. Rubin Observatory — and the discoveries are already starting to roll in. Trifid […]

Detection of HD 135344 Ab with VLT/SPHERE. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

Direct Imaging Discovery Of A Young Giant Planet Orbiting On Solar System Scales

by Keith CowingJuly 9, 2025July 9, 2025

HD 135344 AB is a young visual binary system that is best known for the protoplanetary disk around the secondary star. The circumstellar environment of the A0-type primary star, on […]

χ2 maps for the CS RT models. The free parameters f0 and Re are on the x− and y−axes, respectively. The red + sign denotes the best-fit model, and the white contours correspond to the 1σ, 2σ, and 3σ ranges. -- astro-ph.SR

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report

Charting Circumstellar Chemistry of Carbon-rich Asymptotic Giant Branch Stars. II. Abundances and Spatial Distributions of CS

by Keith CowingJune 1, 2025June 1, 2025

The circumstellar envelopes (CSEs) of asymptotic giant branch (AGB) stars harbour a rich variety of molecules and are sites of complex chemistry.

The formation of binary PMOs via circumstellar disk encounters. -- Credit DENG Hongping

Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Interstellar, Press Release

New Study Reveals How Rogue Planetary-mass Objects Form In Young Star Clusters

by Keith CowingMarch 12, 2025March 12, 2025

A groundbreaking study published in Science Advances sheds new light on the mysterious origins of free-floating planetary-mass objects (PMOs)—celestial bodies with masses between stars and planets.

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

PDS 70b Shows Stellar-like Carbon-to-Oxygen Ratio

by Keith CowingNovember 25, 2024November 25, 2024

The ∼5 Myr PDS 70 is the only known system with protoplanets residing in the cavity of the circumstellar disk from which they formed, ideal for studying exoplanet formation and […]

[left] A Hubble Space Telescope false-color view of a 100-billion-mile-wide disk of dust around the summer star Vega. Hubble detects reflected light from dust that is the size of smoke particles largely in a halo on the periphery of the disk. The disk is very smooth, with no evidence of embedded large planets. The black spot at the center blocks out the bright glow of the hot young star. [right] The James Webb Space Telescope resolves the glow of warm dust in a disk halo, at 23 billion miles out. The outer disk (analogous to the solar system’s Kuiper Belt) extends from 7 billion miles to 15 billion miles. The inner disk extends from the inner edge of the outer disk down to close proximity to the star. There is a notable dip in surface brightness of the inner disk from approximately 3.7 to 7.2 billion miles. The black spot at the center is due to lack of data from saturation. NASA, ESA, CSA, STScI, S. Wolff (University of Arizona), K. Su (University of Arizona), A. Gáspár (University of Arizona) larger image

Astrogeology, Astronomy & Telescopes, Exoplanets, -moons, -comets, Fomalhaut, Imaging & Spectroscopy, Press Release, Stellar Cartography

Hubble And Webb Study The Surprisingly Smooth Disk Around Vega

by Keith CowingNovember 1, 2024September 5, 2025

In the 1997 movie “Contact,” adapted from Carl Sagan’s 1985 novel, the lead character scientist Ellie Arroway (played by actor Jodi Foster) takes a space-alien-built wormhole ride to the star […]