Results 21 to 30 of about 15,774,260 (349)
Calibration of the Hα Age–Activity Relation for M Dwarfs [PDF]
Astronomical Journal, 2021 In this work, we calibrate the relationship between Hα emission and M dwarf ages. We compile a sample of 892 M dwarfs with Hα equivalent width (Hα EW) measurements from the literature that are either comoving with a white dwarf of known age (21 stars) or
Rocio Kiman +8 more
semanticscholar +1 more source
The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs [PDF]
, 2020 We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. We combine these with prior studies to build a list of 525 known L, T, and Y dwarfs within 20 pc of the Sun, 38 of which are presented here for the first time.
J. Kirkpatrick +51 more
semanticscholar +1 more source
Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics [PDF]
, 2008 While the strong anticorrelation between chromospheric activity and age has led to the common use of the Ca II H and K emission index (R′HK = LHK/Lbol) as an empirical age estimator for solar-type dwarfs, existing activity-age relations produce ...
E. Mamajek, L. Hillenbrand
semanticscholar +1 more source
The Astronomical Journal, 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.
Alexia Bravo +11 more
doaj +1 more source
Evolutionary Models for Very Low-Mass Stars and Brown Dwarfs with Dusty Atmospheres [PDF]
, 2000 We present evolutionary calculations for very low-mass stars and brown dwarfs based on synthetic spectra and nongray atmosphere models which include dust formation and opacity, i.e., objects with Teff ≲ 2800 K.
G. Chabrier +5 more
semanticscholar +1 more source
Astrometry and Photometry for ≈1000 L, T, and Y Dwarfs from the UKIRT Hemisphere Survey
The Astronomical Journal, 2023 We present the positions, proper motions, and near-infrared photometry for 966 known objects with spectral types later than M that were observed as part of the the UKIRT Hemisphere Survey (UHS).
Adam C. Schneider +7 more
doaj +1 more source
Monthly Notices of the Royal Astronomical Society, 2008 We present the results of a proper motion survey of the Hyades to search for brown dwarfs, based on UKIDSS and 2MASS data. This survey covers ~275 square degrees to depth of K~15 mag, equivalent to a mass of 0.05 solar masses assuming a cluster age of 625 Myr. The discovery of 12 L dwarf Hyades members is reported.
Hogan, E. +4 more
openaire +2 more sources
Architecture of dwarf shrubs and dwarf subshrubs of the genus of Thymus L. and Scutellaria L. (Lamiaceae) [PDF]
BIO Web of Conferences, 2021 The structure of 24 species of Thymus and 12 species of Scutellaria was studied using the architectural approach. For the first time, an architectural unit was described, it is a branched sympodial axis. The architectural unit consists of sympodial axes n+1 order, formation shoots, branching shoots, ephemerous shoots.
Cheryomushkina Vera +2 more
openaire +2 more sources
THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS [PDF]
, 2016 We present a large, uniform analysis of young (≈10–150 Myr) ultracool dwarfs, based on new high-precision infrared (IR) parallaxes for 68 objects. We find that low-gravity (vl-g) late-M and L dwarfs form a continuous sequence in IR color–magnitude ...
Michael C. Liu, T. Dupuy, K. Allers
semanticscholar +1 more source
Keck Imaging of Binary L Dwarfs [PDF]
The Astrophysical Journal, 1999 LaTex manuscript in 13 pages, 3 postscript figures, Accepted for publication in the Letters of the Astrophysical Journal; Postscript pre-print version available at: http://www.hep.upenn.edu/PORG/papers/koerner99a ...
Koerner, D. W. +3 more
openaire +3 more sources