Brown Dwarfs Archives

Schematic of the observing routine on Jupiter by VLT/ESPRESSO on the 22 July 2019. The small circles represent the FOV of the fibre proportional to the size of Jupiter’s disk in the context of these observations (0.5 arc seconds in diameter for the size of the FOV), and their respective labels. We also included a grid to tentatively map the relative position of each observing position in latitude and longitude. Grid lines have intervals of 15∘ on both coordinates. The solid black line on the right side of the spherical grid represents the morning terminator, while the blue dotted line marks the location of the 12 h local time meridian. The picture of the planet’s disk was taken from the Planetary Virtual Observatory and Laboratory. Picture credits go to Gary Walker.

Astronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Jupiter, Press Release

Comparative Exolanetology: Jupiter Targeted By VLT/ESPRESSO Exoplanet Hunter

by Keith CowingDecember 26, 2023December 26, 2023

For the first time, an instrument to find planets light years away was used on an object in the Solar System, in a study on Jupiter’s winds.

This image from the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope shows the central portion of the star cluster IC 348. The wispy curtains filling the image are interstellar material reflecting the light from the cluster’s stars – what is known as a reflection nebula. The material also includes carbon-containing molecules known as polycyclic aromatic hydrocarbons, or PAHs. Winds from the most massive stars in the cluster may help sculpt the large loop seen on the right side of the field of view. NASA, ESA, CSA, STScI, K. Luhman (Penn State University), and C. Alves de Oliveira (ESA) larger image

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

Webb Identifies The Smallest Free-Floating Brown Dwarf Yet Observed

by Keith CowingDecember 13, 2023December 13, 2023

Brown dwarfs are objects that straddle the dividing line between stars and planets. They form like stars, growing dense enough to collapse under their own gravity, but they never become […]

Contour plot of the normalised contribution function, illustrating the pressure levels of the model atmosphere contributing to the emission from the top of the atmosphere at a given wavelength. The model has Teff = 800 K, log(g) = 4.5, Z = 0.0 and C/O = 0.55. -- astro-ph.SR

Astrochemistry, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

The Carbon-to-Oxygen Ratio in Cool Brown Dwarfs and Giant Exoplanets. I. The Benchmark Late-T dwarfs GJ 570D, HD 3651B and Ross 458C

by Keith CowingDecember 6, 2023December 6, 2023

Measurements of the C/O ratio in brown dwarfs are lacking, in part due to past models adopting solar C/O only. We have expanded the ATMO 2020 atmosphere model grid to […]

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report

Dynamically Coupled Kinetic Chemistry In Brown Dwarf Atmospheres — II. Cloud And Chemistry Connections In Directly Imaged Sub-Jupiter Exoplanets

by Keith CowingDecember 4, 2023December 4, 2023

With JWST slated to gain high fidelity time dependent data on brown dwarf atmospheres, it is highly anticipated to do the same for directly imaged, sub-Jupiter exoplanets.

Comparison of spectra for WISE 0855 from Gemini/GNIRS (Skemer et al. 2016; Morley et al. 2018; Miles et al. 2020) and JWST/NIRSpec (this work). -- astro-ph.SR

Astronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Imaging & Spectroscopy, Status Report

JWST/NIRSpec Observations Of The Coldest Known Brown Dwarf

by Keith CowingNovember 30, 2023November 30, 2023

We present 1-5um spectroscopy of the coldest known brown dwarf, WISE J085510.83-071442.5 (WISE 0855), performed with the Near-Infrared Spectrograph (NIRSpec) on board the James Webb Space Telescope (JWST).

Observed SOAR/TripleSpec4.1 spectra for W0727−3607 (top), W1036−5144 (middle), and W1344−7320 (bottom), with gray lines showing the full resolution and black lines showing the spectra smoothed to the resolution of the standards and binary templates (R≈150) according to their parallax-based absolute fluxes. The left-hand column depicts the best-fitting single standards (orange line) for the spectra of the three candidates while the right-hand column shows both the binary template (orange line) and the standard spectra that compose it (purple line for primary, blue line for secondary). Reduced χ 2 ν values are reported for each of the fits. -- astro-ph.SR

Astronomy & Telescopes, Brown Dwarfs, Citizen Science / Open Science, Education and Outreach, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

An Investigation of New Brown Dwarf Spectral Binary Candidates From the Backyard Worlds: Planet 9 Citizen Science Initiative

by Keith CowingNovember 18, 2023November 18, 2023

We present three new brown dwarf spectral binary candidates: CWISE J072708.09−360729.2, CWISE J103604.84−514424.4, and CWISE J134446.62−732053.9, discovered by citizen scientists through the Backyard Worlds: Planet 9 project.

Comparison of the 14N/15N ratio in the solar neighbourhood. The values are based on either ammonia isotopologues (orange circles) or other molecules (black symbols), in different environments, subdivided by classes7 . Our estimate for WISE J1828 appears as the brown dwarf class and is consistent with solar values (dashed horizontal yellow line) at the 1-2 σ level. Lower values indicate enrichment in 15N, while the dashed blue line represents the current value of the interstellar medium (ISM). -- astro-ph.SR

Astrochemistry, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report

15NH3 In The Atmosphere Of A Cool Brown Dwarf

by Keith CowingNovember 16, 2023November 16, 2023

Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits as the governing physical and chemical processes in them are nearly identical. Understanding the […]

Artistic impression of brown dwarf WISE J1828, one of the coldest gas giants know outside of our Solar System. Its atmosphere is dominated by the absorption from water, methane and ammonia vapour. -- ETH Zurich

Astrochemistry, Brown Dwarfs, Exoplanets, -moons, -comets, Press Release

An Ammonia Trail To Exoplanets

by Keith CowingNovember 7, 2023April 14, 2026

They reveal the origin of wine, the age of bones and fossils, and they serve as diagnostic tools in medicine. Isotopes and isotopologues – molecules that differ only in the […]

The black line is the observed spectrum of WISE 035934.06-540154.6 from Beiler et al. (2023). Black points represent their photometric measurements. The pink line and dots are the best fit Sonora model spectrum and photometry, from Beiler et al. The blue line and data points are the spectrum and photometry from the best fit model of the ATMO2020++ grid. The green line is the same model where PH3 has been removed from the atmospheric composition. The ATMO2020++ model is scaled by the known distance to WISE 0359 (Kirkpatrick et al. 2021) and the radius inferred from evolutionary models (Marley et al. 2021), and has not been scaled to fit. Principal opacity species are indicated. The lower panel shows the difference between the observed spectrum and the spectra generated by the three models (note the difference in y-axis scale in the upper and lower panels). The inset shows the near-infrared flux region. See Section 3 for discussion. -- astro-ph.SR

Astrochemistry, Brown Dwarfs, Status Report

The First Y Dwarf Data From JWST Show That Dynamic and Diabatic Processes Regulate Cold Brown Dwarf Atmospheres

by Keith CowingOctober 1, 2023October 1, 2023

The James Webb Space Telescope (JWST) is now observing Y dwarfs, the coldest known brown dwarfs, with effective temperatures T_eff <= 475 K.

Abundance profiles for selected condensates. Left panel: iron-bearing condensates, middle panel: magnesium and calcium species, right panel: Na and K condensates. The solid lines refer to the equilibrium condensation calculations. Dashed lines indicate the results for the rainout approximation. -- astro-ph.EP

Astrochemistry, Astrogeology, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report

FastChem Cond: Equilibrium Chemistry with Condensation and Rainout for Cool Planetary and Stellar Environments

by Keith CowingSeptember 6, 2023September 6, 2023

Cool astrophysical objects, such as (exo)planets, brown dwarfs, or asymptotic giant branch stars, can be strongly affected by condensation. Condensation does not only directly affect the chemical composition of the […]

Brown Dwarfs

Comparative Exolanetology: Jupiter Targeted By VLT/ESPRESSO Exoplanet Hunter

Webb Identifies The Smallest Free-Floating Brown Dwarf Yet Observed

The Carbon-to-Oxygen Ratio in Cool Brown Dwarfs and Giant Exoplanets. I. The Benchmark Late-T dwarfs GJ 570D, HD 3651B and Ross 458C

Dynamically Coupled Kinetic Chemistry In Brown Dwarf Atmospheres — II. Cloud And Chemistry Connections In Directly Imaged Sub-Jupiter Exoplanets

JWST/NIRSpec Observations Of The Coldest Known Brown Dwarf

An Investigation of New Brown Dwarf Spectral Binary Candidates From the Backyard Worlds: Planet 9 Citizen Science Initiative

15NH3 In The Atmosphere Of A Cool Brown Dwarf

An Ammonia Trail To Exoplanets

The First Y Dwarf Data From JWST Show That Dynamic and Diabatic Processes Regulate Cold Brown Dwarf Atmospheres

FastChem Cond: Equilibrium Chemistry with Condensation and Rainout for Cool Planetary and Stellar Environments

5 Questions About Astrobiology’s Future At NASA

The First Decade of Breakthrough Listen

Mars’ Oddest Cloud May Be Even Odder Than We Thought

A Technosignature Survey Of The Anti-Solar Point: The SETI Institute’s Largest-Ever Campaign With The Allen Telescope Array

Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) II. Approach To Data Reduction And Products For Line-rich Broadband (sub)millimeter Spectra