Daniel FischerMar 12
Spitzer + HST parallaxes of 13 late T and Y dwarfs: https://arxiv.org/abs/2603.08984 -> "We present astrometric measurements for 13 cold #BrownDwarfs in the solar neighborhood (d < 20pc). By combining archival Spitzer data with our own Hubble Space Telescope (HST) observations, we achieve parallax uncertainties typically around 10%. Using Spitzer and HST photometry we compare our targets with other known late T and Y dwarfs in the Solar neighborhood, confirming that there is large intrinsic scatter in the near- and mid-infrared absolute magnitudes and colors of this population, further highlighting the diversity observed spectroscopically by several James Webb Space Telescope (JWST) programs."
Spitzer + HST parallaxes of 13 late T and Y dwarfs

We present astrometric measurements for 13 cold brown dwarfs in the solar neighborhood (d < 20pc). By combining archival Spitzer data with our own Hubble Space Telescope (HST) observations, we achieve parallax uncertainties typically around 10%. Using Spitzer and HST photometry we compare our targets with other known late T and Y dwarfs in the Solar neighborhood, confirming that there is large intrinsic scatter in the near- and mid-infrared absolute magnitudes and colors of this population, further highlighting the diversity observed spectroscopically by several James Webb Space Telescope (JWST) programs. This scatter makes photometric distance estimates highly unreliable and, therefore, makes astrometric parallax measurements fundamental for a meaningful characterization of even the nearest cold brown dwarfs.

arXiv.org
German Virtual ObservatoryMar 3
New in the #VirtualObservatory: “Keck/NIRES spectrum for CWISE J105512.11+544328.3” by Robbins G. et al.
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/958/94
#BrownDwarfs #Spectroscopy #InfraredAstronomy #YDwarfs
VizieR J/ApJ/958/94

VizieR catalogues

The Perpetually Curious!Feb 2

🌌 Some cosmic objects exist at the threshold. Too massive for planetary peace, too small for stellar fire, they drift through ages in slow surrender to darkness.

✍️ Discover these failed stars between worlds 🔭: https://TPC8.short.gy/OdqADo74

✨ Where physics draws boundaries, nature paints twilight

#BrownDwarfs #Astrophysics #CosmicThresholds #Physics #StellarEvolution #Astronomy #Space #TPC8

Brown Dwarfs: Failed Stars at the Universe's Threshold 🌟

Discover brown dwarfs: failed stars between planets & suns. Physics of 13-84 Jupiter masses, eternal cooling, and cosmic significance explained.

German Virtual ObservatoryFeb 1
New in the #VirtualObservatory: “TOI-5389 & TOI-5610 photometry & radial velocities” by Larsen A. et al.
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/169/246
#DwarfStars #BrownDwarfs #MStars #Photometry
VizieR J/AJ/169/246

VizieR catalogues

German Virtual ObservatoryNov 16
New in the #VirtualObservatory: “WISEP J173835.52+273258.9 JWST/MIRI spectrum” by Vasist M. et al.
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/703/A70
#BrownDwarfs #InfraredAstronomy #Spectroscopy
VizieR J/A+A/703/A70

VizieR catalogues

German Virtual ObservatoryNov 14
New in the #VirtualObservatory: “FIRE MRS spectrum of the BD UGPSJ072227.51-054031.2” by Hood C.E. et al.
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/953/170
#BrownDwarfs #TDwarfs #InfraredAstronomy #Spectroscopy
VizieR J/ApJ/953/170

VizieR catalogues

Daniel FischerOct 1
The JWST Weather Report - retrieving temperature variations, auroral heating, and static cloud coverage on SIMP-0136: https://arxiv.org/abs/2507.07772 -> Brauner Zwerg - Polarlichter auf einem kuriosen Himmelskörper: https://www.tagesspiegel.de/wissen/james-webb-weltraumteleskop-brauner-zwerg-polarlichter-auf-einem-kuriosen-himmelskorper-14408018.html #BrownDwarfs
The JWST Weather Report: retrieving temperature variations, auroral heating, and static cloud coverage on SIMP-0136

SIMP-0136 is a T2.5 brown dwarf whose young age ($200\pm50$~Myr) and low mass ($15\pm3$~M$_{\rm Jup}$) make it an ideal analogue for the directly imaged exoplanet population. With a 2.4 hour period, it is known to be variable in both the infrared and the radio, which has been attributed to changes in the cloud coverage and the presence of an aurora respectively. To quantify the changes in the atmospheric state that drive this variability, we obtained time-series spectra of SIMP-0136 covering one full rotation with both NIRSpec/PRISM and the MIRI/LRS on board JWST. We performed a series of time-resolved atmospheric retrievals using petitRADTRANS in order to measure changes in the temperature structure, chemistry, and cloudiness. We inferred the presence of a ~250 K thermal inversion above 10 mbar of SIMP-0136 at all phases, and propose that this inversion is due to the deposition of energy into the upper atmosphere by an aurora. Statistical tests were performed in order to determine which parameters drive the observed spectroscopic variability. The primary contribution was due to changes in the temperature profile at pressures deeper than 10 mbar, which resulted in variation of the effective temperature from 1243 K to 1248 K. This changing effective temperature was also correlated to observed changes in the abundances of CO2 and H2S, while all other chemical species were consistent with being homogeneous throughout the atmosphere. Patchy silicate clouds were required to fit the observed spectra, but the cloud properties were not found to systematically vary with longitude. This work paints a portrait of an L/T transition object where the primary variability mechanisms are magnetic and thermodynamic in nature, rather than due to inhomogeneous cloud coverage.

arXiv.org
German Virtual ObservatorySep 26
New in the #VirtualObservatory: “Characterization of the X-Shyne library” by Petrus S. et al.
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/701/A208
#BrownDwarfs #EffectiveTemperature #LineIntensities #ChemicalAbundances
VizieR J/A+A/701/A208

VizieR catalogues

NASASep 9, 2025
NASA Study: Celestial ‘Accident’ Sheds Light on Jupiter, Saturn Riddle https://www.nasa.gov/missions/webb/nasa-study-celestial-accident-sheds-light-on-jupiter-saturn-riddle/ #NASA #JamesWebbSpaceTelescopeJWST #BrownDwarfs #Exoplanets #TheSearchForLife
NASA Study: Celestial ‘Accident’ Sheds Light on Jupiter, Saturn Riddle - NASA

An unusual cosmic object is helping scientists better understand the chemistry hidden deep in Jupiter and Saturn’s atmospheres — and potentially those of

NASA
Massimo LucianiAug 20, 2025

#TachyonBeam #astronomy #stars #RedDwarfs #BrownDwarfs

An article published in the journal "Monthly Notices of the Royal Astronomical Society" (MNRAS) reports the discovery of a rare hierarchical quadruple system, which was cataloged as UPM J1040−3551 AabBab. A team of researchers used various observations to identify this quartet consisting of a pair of red dwarfs and a pair of brown dwarfs.

https://english.tachyonbeam.com/2025/08/20/rare-hierarchical-quadruple-system-discovered-with-two-red-dwarfs-and-two-brown-dwarfs/