Results 81 to 90 of about 74,495 (201)

Photometric Accretion Signatures Near the Substellar Boundary

, 2005
Multi-epoch imaging of the Orion equatorial region by the Sloan Digital Sky Survey has revealed that significant variability in the blue continuum persists into the late-M spectral types, indicating that magnetospheric accretion processes occur below the
Andrew A. West, Armitage P. J., Baraffe I., Briceno C., Brown A. G. A., de Geus E. J., Guillout P., J. Allyn Smith, J. Brinkmann, Kurt S. J. Anderson, Neuhauser R., Peregrine M. McGehee, Wiramihardja S. D.   +12 more
core   +1 more source

Spectroscopic and physical parameters of Galactic O-type stars. I. Effects of rotation and spectral resolving power in the spectral classification of dwarfs and giants

, 2011
The modern-era spectral classification of O-stars relies on either the Walborn or the Conti-Mathys scheme. Since both of these approaches have been developed using low-quality photographic data, their application to high-quality digital data might not be
A. Herrero, Balona, Balona, Bouret, Conti, Conti, Conti, Conti, Crampton, Crampton, Duflot, Dufton, Feast, Feast, Fullerton, Garcia, Garrison, Georgelin, Gies, Herrero, Howarth, J. Puls, Kaufer, Kilkenny, Lefevre, Levato, Levato, Levato, Loden, Marchenko, Marcolino, Markova, Martins, Martins, Mason, Mason, Massey, Mathys, Mathys, Moffat, Morrell, Morris, N. Markova, Nesterov, Penny, Penny, Penny, Penny, Peton-Jonas, Puls, Puls, Puls, Rabaud, Reed, Reed, Repolust, S. Scuderi, S. Simón-Díaz, Sana, Schild, Solivella, Turner, Turner, Walborn, Walborn, Walborn, Walborn, Walborn, Walborn   +68 more
core   +1 more source

A Spectroscopic Survey of Metal-poor OB Stars in Local Dwarf Galaxy NGC 3109

The Astrophysical Journal
As JWST uncovers increasingly strong evidence that metal-poor, massive stars in early galaxies dominated reionization, observational constraints on the properties of such stars are more relevant than ever before.
Abby Mintz, O. Grace Telford, Evan N. Kirby, John Chisholm, Kristen B. W. McQuinn, Danielle A. Berg   +5 more
doaj   +1 more source

Surface effects in solar-like oscillators

EPJ Web of Conferences, 2017
Inaccurate modelling of the near-surface layers of solar models causes a systematic difference between modelled and observed solar mode frequencies. This difference—known as the “surface effect” or “surface term”—presumably also exists in other solar ...
Ball Warrick H.
doaj   +1 more source

Absolute Lineshifts - A new diagnostic for stellar hydrodynamics [PDF]

, 2003
For hydrodynamic model atmospheres, absolute lineshifts are becoming an observable diagnostic tool beyond the classical ones of line-strength, -width, -shape, and -asymmetry.
Dravins, Dainis
core   +2 more sources

The Uv Spectral Window: New Means To Constrain The Stellar Populations Of Early-Type Galaxies

, 2017
We discuss the possibilities of exploiting the UV spectral using the J-PAS survey to disentangle young contributions from apparently old galaxies. We show that the feasibility of determining such young stellar components in early-type galaxies at moderately high redshift.
Vazdekis, Alexandre, Salvador-Rusiñol, Núria, Falcón-Barroso, Jesus, Beasley, Michael, Ricciardelli, Elena   +4 more
openaire   +1 more source

Morphological Feature Distances among the Spectral Types of SDSS Galaxies

The Astrophysical Journal
This study investigates the morphological feature distances among various spectral types of galaxies from the Sloan Digital Sky Survey, including strong and weak active galactic nuclei (AGN), quasi-stellar objects (QSOs), quiescent, and star-forming ...
Duho Kim, Garreth Martin
doaj   +1 more source

Magnetic Activity in M-type Stars Based on LAMOST DR11 and TESS Observations

The Astrophysical Journal Supplement Series
We have used 898,351 M-type stellar spectra released by Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR11 to calculate the equivalent width of the Ca II infrared triplet (IRT) lines, the residual chromospheric emission, and the parameter ${R}
Linfeng Ren, Li-yun Zhang, Xianming L. Han, Tianhao Su, Wenjie Li, Yinpeng Wang, Prabhakar Misra   +6 more
doaj   +1 more source

A Pan-STARRS + UKIDSS Search for Young, Wide Planetary-Mass Companions in Upper Scorpius

, 2013
We have combined optical and NIR photometry from Pan-STARRS 1 and UKIDSS to search the young (5-10 Myr) star-forming region of Upper Scorpius for wide (~400-4000 AU) substellar companions down to ~5 Mjup.
Aller, Kimberly M., Burgett, William S., Chambers, Kenneth C., Hodapp, Klaus W., Kaiser, Nick, Kraus, Adam L., Liu, Michael C., Magnier, Eugene A., Price, Paul A.   +8 more
core   +1 more source

International Ultraviolet Explorer Atlas of O-typespectra from 1200 to 1900 Angstrom [PDF]

The IUE archives provide an unprecedented sample of uniform, high-quality ultraviolet stellar spectra. In particular, they contain high-resolution SWP data for nearly 200 different O stars.
Nichols-Bohlin, J., Panek, R. J., Walborn, N. R.   +2 more
core   +1 more source