Results 91 to 100 of about 74,495 (201)

The California Legacy Survey. V. Chromospheric Activity Cycles in Main-sequence Stars

The Astrophysical Journal Supplement Series
We present optical spectroscopy of 710 solar neighborhood stars collected over 20 years to catalog chromospheric activity and search for stellar activity cycles.
Howard Isaacson, Andrew W. Howard, Benjamin Fulton, Erik A. Petigura, Lauren M. Weiss, Stephen R. Kane, Brad Carter, Corey Beard, Steven Giacalone, Judah Van Zandt, Joseph M. Akana Murphy, Fei Dai, Ashley Chontos, Alex S. Polanski, Malena Rice, Jack Lubin, Casey Brinkman, Ryan A. Rubenzahl, Sarah Blunt, Samuel W. Yee, Mason G. MacDougall, Paul A. Dalba, Dakotah Tyler, Aida Behmard, Isabel Angelo, Daria Pidhorodetska, Andrew W. Mayo, Rae Holcomb, Emma V. Turtelboom, Michelle L. Hill, Luke G. Bouma, Jingwen Zhang, Ian J. M. Crossfield, Nicholas Saunders   +33 more
doaj   +1 more source

Spectroscopy of Brown Dwarf Candidates in the rho Ophiuchi Molecular Core

, 1998
We present an analysis of low resolution infrared spectra for 20 brown dwarf candidates in the core of the $\rho$ Ophiuchi molecular cloud. Fifteen of the sources display absorption-line spectra characteristic of late-type stars.
Briceno C., Bruce A. Wilking, Calvet N., Casoli M., Comeron F., D'Antona F., Dent W. R. F., Hartmann L., Jones H. R. A., Kenyon S. J., Lynden-Bell D., Michael R. Meyer, Perrin G., Schiavon R. P., Thomas P. Greene   +14 more
core   +2 more sources

Three-dimensional simulations of near-surface convection in main-sequence stars. III. The structure of small-scale magnetic flux concentrations

, 2015
The convective envelopes of cool main-sequence stars harbour magnetic fields with a complex global and local structure. These fields affect the near-surface convection and the outer stellar atmospheres in many ways and are responsible for the observable ...
Beeck, Benjamin, Cameron, Robert H., Reiners, Ansgar, Schüssler, Manfred   +3 more
core   +2 more sources

Stellar mass-to-light ratios from galaxy spectra: how accurate can they be?

, 2009
Stellar masses play a crucial role in the exploration of galaxy properties and the evolution of the galaxy population. In this paper, we explore the minimum possible uncertainties in stellar mass-to-light (M/L) ratios from the assumed star formation ...
Bell, Eric F., Gallazzi, Anna
core   +1 more source

The ages and metallicities of galaxies in the local universe

, 2005
We derive stellar metallicities, light-weighted ages and stellar masses for a magnitude-limited sample of 175,128 galaxies drawn from the Sloan Digital Sky Survey Data Release Two (SDSS DR2).
Brinchmann, Jarle, Charlot, Stephane, Gallazzi, Anna, Tremonti, Christy A., White, Simon D. M.   +4 more
core   +3 more sources

Stellar Angular Diameters and Visual Surface Brightness -- I LATE SPECTRAL TYPES [PDF]

Monthly Notices of the Royal Astronomical Society, 1976
T. G. Barnes, D. S. Evans
openaire   +1 more source

Observations of Extremely Metal-poor O Stars: Weak Winds and Constraints for Evolution Models

The Astrophysical Journal
Metal-poor massive stars drive the evolution of low-mass galaxies, both locally and at high redshift. However, quantifying the feedback they impart to their local surroundings remains uncertain because models of stellar evolution, mass loss, and ionizing
O. Grace Telford, John Chisholm, Andreas A. C. Sander, Varsha Ramachandran, Kristen B. W. McQuinn, Danielle A. Berg   +5 more
doaj   +1 more source

MSTAT: A Python Tool for Estimating Spectral Types of Stellar Companions from Differential Photometry

Research Notes of the AAS
Abstract A python-based tool for reading the table of absolute magnitudes for dwarf (O-Y) stars as compiled by M. J. Pecaut & E. E. Mamajek and using this table to determine the most likely spectral type for a companion star has been developed.
Miranda Felsmann, David R. Ciardi
openaire   +1 more source

Properties of Flare Quasiperiodic Pulsations Based on a New TESS Flare Catalog

The Astrophysical Journal Supplement Series
Stellar flares are important indicators of stellar magnetic activity and have been widely studied. Detailed studies of flares have raised new questions. For example, the quasiperiodic pulsation (QPP) phenomenon in flares challenges standard flare models,
Yinpeng Wang, Li-yun Zhang, Tianhao Su, Prabhakar Misra, Xianming L. Han   +4 more
doaj   +1 more source

A Chemically Peculiar Star Catalog from LAMOST DR12 Based on Deep Learning

The Astrophysical Journal Supplement Series
Chemically peculiar (CP) stars offer a unique observational sample for exploring key processes in stellar evolution. Leveraging the massive amounts of data obtained from large-scale sky surveys, deep learning technology has significantly advanced ...
Yixing Chen, Hui Deng, Lei Tan, Ying Mei, Feng Wang   +4 more
doaj   +1 more source