Results 111 to 120 of about 22,040,331 (192)

Rotation Periods of Candidate Single Late-M Dwarfs in TESS

The Astronomical Journal
Recent studies suggest that the angular momentum evolution of late-M and brown dwarfs differs from the well-known spin-down evolution of hotter stars. Characterizing the distribution of rotation periods of these objects in the solar neighborhood can help
Samantha Lambier, Stanimir Metchev, Paulo Miles-Páez, Leslie Moranta, Dakota Wolfe, Joelene Hales, Jeffrey Martinovic   +6 more
doaj   +1 more source

The MIRI Excesses Around Degenerates (MEAD) Survey. I. A Candidate Cold Brown Dwarf in Orbit Around the Nearby White Dwarf 2MASS J09424023−4637176

The Astronomical Journal
The MIRI Excesses Around Degenerates Survey is a Cycle 2 James Webb Space Telescope (JWST) survey program designed to image nearby white dwarfs in the mid-IR with the MIRI imaging mode.
Loïc Albert, Sabrina Poulsen, Érika Le Bourdais, John H. Debes, Samuel Boucher, Mukremin Kilic, William Reach, Susan E. Mullally, Misty Cracraft, Fergal Mullally, Matthew De Furio, David A. Golimowski, J. J. Hermes, Scott J. Kenyon, Carl Melis, Seth Redfield, M. C. Wyatt, Patrick Dufour, Jay Farihi, Ashley Messier   +19 more
doaj   +1 more source

A Tale of Two Molecules: The Underprediction of CO2 and Overprediction of PH3 in Late T and Y Dwarf Atmospheric Models

The Astrophysical Journal
The sensitivity and spectral coverage of JWST are enabling us to test our assumptions of ultracool dwarf atmospheric chemistry, especially with regards to the abundances of phosphine (PH _3 ) and carbon dioxide (CO _2 ).
Samuel A. Beiler, Sagnick Mukherjee, Michael C. Cushing, J. Davy Kirkpatrick, Adam C. Schneider, Harshil Kothari, Mark S. Marley, Channon Visscher   +7 more
doaj   +1 more source

Precise Bolometric Luminosities and Effective Temperatures of 23 Late-T and Y Dwarfs Obtained with JWST

The Astrophysical Journal
We present infrared spectral energy distributions of 23 late-type T and Y dwarfs obtained with the James Webb Space Telescope. The spectral energy distributions consist of NIRSpec PRISM and MIRI low-resolution spectrometer spectra covering the ∼1–12 μ m ...
Samuel A. Beiler, Michael C. Cushing, J. Davy Kirkpatrick, Adam C. Schneider, Sagnick Mukherjee, Mark S. Marley, Federico Marocco, Richard L. Smart   +7 more
doaj   +1 more source

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
Marocco, Federico, Kirkpatrick, J. Davy, Smart, Richard L., Schneider, Adam C., Caselden, Dan, Costa, Edgardo, Cushing, Michael C., Dirk, Maximiliano, Eisenhardt, Peter R. M ., Faherty, Jacqueline K., Gelino, Christopher R., Kuchner, Marc J., Meisner, Aaron M., Mendez, Rene A., Stiller, Robert A., Wright, Edward L.   +15 more
openaire   +2 more sources

ROME. IV. An Arecibo Search for Substellar Magnetospheric Radio Emissions in Purported Exoplanet-hosting Systems at 5 GHz

The Astrophysical Journal
Plasma flow–obstacle interactions, such as those between an exoplanet’s magnetosphere and the host star’s stellar wind, may lead to detectable radio emissions.
Matthew Route
doaj   +1 more source

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

The Astrophysical Journal
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 atmosphere. The properties of clouds are governed by complex
James Mang, Caroline V. Morley, Tyler D. Robinson, Peter Gao   +3 more
doaj   +1 more source

Outstanding Issues in Our Understanding of L, T, and Y Dwarfs

, 2007
11 pages including 5 figures.
openaire   +2 more sources

Atmospheric Waves Driving Variability and Cloud Modulation on a Planetary-mass Object

The Astrophysical Journal
Planetary-mass objects and brown dwarfs at the transition ( T _eff ∼ 1300 K) from relatively red L dwarfs to bluer mid-T dwarfs show enhanced spectrophotometric variability.
Michael K. Plummer, Ji Wang, Étienne Artigau, René Doyon, Genaro Suárez   +4 more
doaj   +1 more source

AND ASTROPHYSICS Consistency of the metallicity distributions

, 1998
. The consistency of the metallicity distributions of F, G and K dwarfs is studied. We present a new metallicity distribution for K dwarfs using metallicities determined from uvby photometry.
K Dwarfs, Of Nearby F
core