Brown Dwarfs Archives

An international team of astronomers has used the NASA/ESA/CSA James Webb Space Telescope to detect the first brown dwarf candidates outside the Milky Way in the star cluster NGC 602. larger image - ESA/NASA

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

The First Young Brown Dwarfs Found Outside Our Home Galaxy?

by Keith CowingOctober 23, 2024October 23, 2024

Picture the outskirts of the Small Magellanic Cloud, a satellite galaxy of our Milky Way, roughly 200 000 light-years from Earth: here lies the young star cluster NGC 602. The […]

The MIRI/MRS (this work), NIRspec/PRISM and NIRSpec/G395M Luhman et al. (2024) spectrum of WISE 0855 from 0.8 to 22 µm. Panel a) shows the NIRspec/PRISM data in red and panel from 0.8 to 2.2µm b) the NIRspec/G395M in green and MIRI/MRS data in blue from 2.2 to 22 µm. Insets c) and d) show the overlap between the three data sets from 3.5 to 5.4 µm and the ammonia feature from 8.0 to 13.0 µm, respectively. The most dominant absorbing species are presented above the spectrum in various colors. For better visualization he data was binned to a resolution of R = 1000 for MIRI/MRS and NIRSpec/G395M and R = 100 for NIRSpec/PRISM. -- astro-ph.EP

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

Water Depletion and 15NH3 in the Atmosphere of the Coldest Brown Dwarf Observed With JWST/MIRI

by Keith CowingOctober 17, 2024October 17, 2024

With a temperature of ∼285 K WISE0855 is the coldest brown dwarf observed so far. Using the James Webb Space Telescope (JWST) we obtained observations that allow us to characterize […]

Top: The high-resolution spectrum of the T-dwarf Gl229 B analyzed using ExoJAX2 (Kawashima et al. submitted) with ∼ 108 total molecular absorption lines considered. The blue solid line shows the median value, while the blue shaded regions indicate the 95% credible interval. Black points represent the observed Subaru/IRD data. The periodic increases in the residuals observed correspond to the gaps between orders. Bottom: Medium-resolution transmission spectrum of WASP-39 b analyzed using ExoJAX2 and the HMC-NUTS method. The black solid line represents the model derived from the median values of each parameter obtained through MCMC sampling, with the 95% credible interval shaded in gray. The blue points show the observed planetary radii from JWST NIRSpec/G395H observations. The vertical axis on the left shows the planetary radius, while the vertical axis on the right displays the corresponding pressure. The contributions of CO, CO2, H2O, SO2, gray clouds, and collision-induced absorption (CIA) are represented by colored shading with an offset of -0.01 Rs. -- astro-ph.SR

AI - Data - Apps - Cybernetics, Apps - Games, Astronomy & Telescopes, Brown Dwarfs, Imaging & Spectroscopy, Status Report, Stellar Cartography

Differentiable Modeling of Planet and Substellar Atmosphere: High-Resolution Emission, Transmission, and Reflection Spectroscopy with ExoJAX2

by Keith CowingOctober 10, 2024October 10, 2024

Modeling based on differentiable programming holds great promise for astronomy, as it can employ techniques such as Hamiltonian Monte Carlo, gradient-based optimization, and other machine learning techniques.

This artist’s concept shows a brown dwarf, an object that is at least 13 times the mass of Jupiter but not massive enough to begin nuclear fusion in its core, which is the defining characteristic of a star. Scientist using NASA’s Spitzer Space Telescope recently made the first ever direct measurement of wind on a brown dwarf. Credits: NASA/JPL-Caltech

Astronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report

Physical Parameters and Properties of 20 Cold Brown Dwarfs in JWST

by Keith CowingOctober 6, 2024October 6, 2024

We present a comprehensive analysis of 20 T and Y dwarfs using spectroscopy from the NIRSpec CLEAR/PRISM and MIRI LRS instruments on the James Webb Space Telescope. To characterize the […]

Free-floating Object - Grok via Astrobiology.com

Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

The Origin Of Free-floating Objects In The Galaxy

by Keith CowingOctober 2, 2024October 2, 2024

The Milky way Galaxy is brimming with free-floating objects, including stars, planets and planetesimals. For the purpose of this chapter, we define a free-floating object as a solid body that […]

New image from the James Webb Space Telescope spectroscopic survey of NGC1333. CREDIT ESA/Webb, NASA & CSA, A. Scholz, K. Muzic, A. Langeveld, R. Jayawardhana larger image

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

In Six New Rogue Worlds, Webb Telescope Finds More Star Birth Clues

by Keith CowingAugust 28, 2024August 27, 2024

The James Webb Space Telescope has spotted six likely rogue worlds—objects with planetlike masses but untethered from any star’s gravity—including the lightest ever identified with a dusty disk around it.

Example of the background subtraction process applied to the calibrated slope image cutouts between Stage 2 and Stage 3 of the JWST Science Calibration Pipeline. Top panel: Cutout for one source showing the dispersion of the spectrum (central rows). Rows above and below the spectral trail have a purple hue indicative of the background, which increases in strength towards longer wavelengths. Bottom panel: Following background subtraction, the cutout now only shows significant flux from the source. The color scale is the same for both panels. Data inside the shaded regions are ignored when analyzing the 1D spectrum in the following analysis. White pixels are “NaN” values that do not affect the spectral extraction. -- astro-ph.EP

Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

The JWST/NIRISS Deep Spectroscopic Survey for Young Brown Dwarfs and Free-Floating Planets

by Keith CowingAugust 26, 2024August 26, 2024

The discovery and characterization of free-floating planetary-mass objects (FFPMOs) is fundamental to our understanding of star and planet formation. Here we report results from an extremely deep spectroscopic survey of […]

Simulated Doppler maps for WISE 1049A with injected spot models. On the night of Feb 11, a single polar spot model reproduces the observed map, while on Feb 9, a model with two polar spots is needed to reproduce the observed map. -- astro-ph.EP

Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Brown Dwarfs, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Imaging & Spectroscopy, Status Report

Global Weather Map Reveals Persistent Top-of-atmosphere Features On The Nearest Brown Dwarfs

by Keith CowingAugust 20, 2024August 20, 2024

Brown dwarfs and planetary-mass companions display rotationally modulated photometric variability, especially those near the L/T transition. This variability is commonly attributed to top-of-atmosphere (TOA) inhomogeneities, with proposed models including patchy […]

Simulated thermal emission spectra from 0.6 to 15 µm of a CARMA model, EddySed models with various Scloud values and different fractions of the cloud mass mixing ratio, and a cloud-free model for a Y dwarf with Teff = 175 K, log(g) = 4.5 and fsed = 6. The inset highlights the region of interest between 3.5 - 6 µm. -- astro-ph.EP

Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Microphysical Prescriptions for Parameterized Water Cloud Formation on Ultra-cool Substellar Objects

by Keith CowingAugust 20, 2024

Water must condense into ice clouds in the coldest brown dwarfs and exoplanets. When they form, these icy clouds change the emergent spectra, temperature structure, and albedo of the substellar […]

The population of transiting exoplanets and brown dwarfs, as obtained from TEPCat [6], marker size corresponds to equilibrium temperature. Targets being observed in Cycle 1 and/or 2 are highlighted accordingly, their temperature is further indicated by their color, and the histogram shows the number of targets as a function of mass. The red line indicates the lowest mass objects being characterized through direct techniques to date. -- astro-ph.IM

Astronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report

The Unrealised Interdisciplinary Advantage of Observing High Mass Transiting Exoplanets and Brown Dwarfs — Strategic Exoplanet Initiatives with HST and JWST White Paper

by Keith CowingAugust 18, 2024August 17, 2024

We advocate for further prioritisation of atmospheric characterisation observations of high mass transiting exoplanets and brown dwarfs.

Brown Dwarfs

The First Young Brown Dwarfs Found Outside Our Home Galaxy?

Water Depletion and 15NH3 in the Atmosphere of the Coldest Brown Dwarf Observed With JWST/MIRI

Differentiable Modeling of Planet and Substellar Atmosphere: High-Resolution Emission, Transmission, and Reflection Spectroscopy with ExoJAX2

Physical Parameters and Properties of 20 Cold Brown Dwarfs in JWST

The Origin Of Free-floating Objects In The Galaxy

In Six New Rogue Worlds, Webb Telescope Finds More Star Birth Clues

The JWST/NIRISS Deep Spectroscopic Survey for Young Brown Dwarfs and Free-Floating Planets

Global Weather Map Reveals Persistent Top-of-atmosphere Features On The Nearest Brown Dwarfs

Microphysical Prescriptions for Parameterized Water Cloud Formation on Ultra-cool Substellar Objects

The Unrealised Interdisciplinary Advantage of Observing High Mass Transiting Exoplanets and Brown Dwarfs — Strategic Exoplanet Initiatives with HST and JWST White Paper

5 Questions About Astrobiology’s Future At NASA

NASA Is Forfeiting Its Global Astrobiology Leadership

Oxidation Of Photochemical Organic Hazes: A Prebiotic Source of Oxygen-Bearing Organics in Titan’s Atmosphere And Early Earth?

Offworld Biotech: Nikon Experimentation Microscope in Orbit (NEMO) (Video)

Paleo-heat Flux Estimates Across Enceladus Derived From Flexural Response Of The Ice Shell