scholarly journals Chromospheric activities of late-type stars based on Guoshoujing Telescope

2013 ◽  
Vol 9 (S298) ◽  
pp. 454-454
Author(s):  
L. Y. Zhang ◽  
G. Y. Zhang ◽  
J. R. Shi ◽  
A. L. Luo ◽  
J. K. Zhao ◽  
...  
Keyword(s):  
Late Type ◽  
Stellar Spectrum ◽  
Active Stars ◽  
M Stars

AbstractWe present chromospheric activities of late-type stars based on stellar spectrum survey of LAMOST (also called GuoShouJing telescope) in 2010-2013. Using the equivalent widths of the Hα line (larger than 1 Å), we have found 6391 active stars from 99741 M stars.

scholarly journals Chromospheric activity of late-type stars based on Guoshoujing Telescope

2012 ◽  
Vol 8 (S294) ◽  
pp. 209-210 ◽  
Author(s):  
Liyun Zhang ◽  
Jianrong Shi ◽  
Jingkun Zhao ◽  
Ali Luo ◽  
Guoyin Zhang ◽  
...  
Keyword(s):  
Late Type ◽  
Stellar Spectrum ◽  
Pilot Survey ◽  
Preliminary Results ◽  
Chromospheric Activity ◽  
M Stars

AbstractWe introduced our preliminary results of chromospheric activity of late-type stars based on the stellar spectrum of the pilot survey of the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST, also called Guo Shou Jing telescope). We have found 1151 active M stars from 17471 M samples using the chromospheric active indicator of the Hα line.

scholarly journals Giant planets around AF and M stars

2013 ◽  
Vol 8 (S299) ◽  
pp. 64-65
Author(s):  
Julien Rameau ◽  
Gaël Chauvin ◽  
Anne-Marie Lagrange ◽  
Philippe Delorme ◽  
Justine Lannier
Keyword(s):  
Giant Planets ◽  
Early Type ◽  
Late Type ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Planetary Mass ◽  
Nearby Stars ◽  
Low Mass ◽  
M Stars ◽  
The One

AbstractWe present the results of two three-year surveys of young and nearby stars to search for wide orbit giant planets. On the one hand, we focus on early-type and massive, namely β Pictoris analogs. On the other hand, we observe late type and very low mass stars, i.e., M dwarfs. We report individual detections of new planetary mass objects. According to our deep detection performances, we derive the observed frequency of giant planets between these two classes of parent stars. We find frequency between 6 to 12% but we are not able to assess a/no correlation with the host-mass.

scholarly journals Quiescent and flaring lyman-α radiation of host stars and effects on exoplanets

2015 ◽  
Vol 11 (S320) ◽  
pp. 391-396
Author(s):  
Jeffrey L. Linsky ◽  
Kevin France ◽  
Yamila Miguel ◽  
Lisa Kaltenegger
Keyword(s):  
Emission Lines ◽  
Late Type ◽  
Chemical Abundances ◽  
Interstellar Absorption ◽  
Ultraviolet Spectra ◽  
M Stars ◽  
Host Stars ◽  
Stars Flare ◽  
Photochemical Models

AbstractLyman-α radiation dominates the ultraviolet spectra of G, K, and M stars and is a major photodissociation source for H2O, CO2, and CH4 in the upper atmospheres of exoplanets. We obtain intrinsic Lyman-α line fluxes for late-type stars by correcting for interstellar absorption or by scaling from other spectroscopic observables. When stars flare, all emission lines brighten by large factors as shown by HST spectra. We describe photochemical models of the atmosphere of the mini-Neptune GJ 436b (Miguel et al. 2015) that show the effects of flaring Lyman-α fluxes on atmospheric chemical abundances.

scholarly journals Radio Emission from Flares in Single Late-type Stars

1995 ◽  
Vol 151 ◽  
pp. 22-31
Author(s):  
Arnold O. Benz
Keyword(s):  
Radio Emission ◽  
High Energy ◽  
Primary Energy ◽  
Relativistic Electrons ◽  
Late Type ◽  
Loss Cone ◽  
Magnetically Trapped ◽  
Stellar Flares ◽  
Gyrosynchrotron Emission ◽  
M Stars

AbstractRadio observations provide the most direct information on non-thermal electrons in stellar flares and in the coronae of late-type stars. Radio emissions of single main-sequence F, G, and of many K stars have recently been discovered, in addition to the well-known dwarf M stars. Their long-duration radio flares with low circular polarization, slow variations and broad bandwidth can be attributed to gyrosynchrotron emission of mildly relativistic electrons. The same holds for the low-level (‘quiescent’) radio emission. On the other hand, highly polarized radio flares of M stars have been interpreted by coherent emissions from loss-cone instabilities of magnetically trapped electrons. These conjectures are consistent with recent VLBI observations. The identification of the radio emission process allows to estimate the high-energy component of the flare and compare it to the total flare energy. The weakly polarized radio emission may serve as a proxy for hard X-ray signatures of relativistic electrons. The fraction of primary energy released into energetic electrons then appears to be large and similar to solar flares.

Late-Type Active Stars: Rotation & Companions

2006 ◽  
Vol 304 (1-4) ◽  
pp. 195-197 ◽  
Author(s):  
T. H. Dall ◽  
K. G. Strassmeier ◽  
H. Bruntt
Keyword(s):  
Late Type ◽  
Active Stars

Faint Sources in the EUVE Survey. II. Identification of Two White Dwarfs and Four Late-Type Active Stars.

1997 ◽  
Vol 114 ◽  
pp. 1567 ◽  
Author(s):  
Stephane Vennes ◽  
Eric Korpela ◽  
Stuart Bowyer
Keyword(s):  
White Dwarfs ◽  
Late Type ◽  
Active Stars

Investigation of late-type stars in the FBS survey. I. M stars

Astrophysics ◽  
1994 ◽  
Vol 37 (1) ◽  
pp. 44-50 ◽  
Author(s):  
H. V. Abrahamian ◽  
V. V. Hambarian ◽  
K. S. Gigoyan
Keyword(s):  
Late Type ◽  
M Stars

scholarly journals Extensions of the Wilson-Bappu Effect Among Very Luminous Stars

1978 ◽  
Vol 80 ◽  
pp. 59-62
Author(s):  
Robert E. Stencel
Keyword(s):  
Emission Lines ◽  
Full Width ◽  
Half Maximum ◽  
Late Type ◽  
New Class ◽  
Line Core ◽  
M Stars ◽  
Type Giant

Twenty years ago, Wilson and Bappu (1957) published their observational correlation of MVand the logarithm of the full width at half maximum of the CaII K-line central emission for G, K and M stars. The technique was stated to have ± 0m.5 accuracy, while a tabulation of MV(K) by Wilson (1976) suggests the error may only be ± 0m.3. This accuracy makes the approach valuable for late-type supergiants since other methods suffer from comparable errors. However, for F through M supergiants (Ia, 0), circumstellar absorption obscures the chromospheric K-line core emission and excludes such objects from the Wilson-Bappu correlation. I report here on a new class of emission lines in late-type giant and supergiant spectra that exhibit MVcorrelated widths, yet are detectable among the brightest stars.

scholarly journals Late-Type Giants in the Bulge, at High Galactic Latitudes and in the Plane

1996 ◽  
Vol 169 ◽  
pp. 411-417
Author(s):  
Patricia Whitelock
Keyword(s):  
Near Infrared ◽  
Large Range ◽  
Scale Height ◽  
Late Type ◽  
The South ◽  
Strong Function ◽  
Period Distribution ◽  
M Stars ◽  
K 12 ◽  
Galactic Distribution

Mira and non-Mira M stars are easily distinguished by means of their near-infrared colours. The Miras show a large range of mass-loss rates, and the actual rates are a strong function of the K-[12] colour. The kinematics and scale heights of these Miras are a function of their pulsation periods. The period distribution of Miras in the South Galactic Cap is similar to that of Miras in the Bulge. Non-Mira M stars in the South Galactic Cap have similar colours to their counterparts in the Bulge but differ from bright M-giants in the solar neighbourhood. The galactic distribution and scale height of the M giants is a function of colour and it is suggested that differences in composition influence the colours.

Sign in / Sign up

Export Citation Format

Share Document