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 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 Environmental Effects in Galaxy Clusters: Infalling Groups in Abell 85 and 1367

2010 ◽  
Vol 6 (S277) ◽  
pp. 296-299
Author(s):  
H. Bravo-Alfaro ◽  
T. C. Scott ◽  
E. Brinks ◽  
L. Cortese ◽  
P. Granados ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Environmental Effects ◽  
Compact Groups ◽  
Late Type ◽  
Gravitational Effects ◽  
Groups Of Galaxies ◽  
Preliminary Results ◽  
Nir Imaging ◽  
Gaseous Component ◽  
Global Cluster

AbstractWe are carrying out a multifrequency survey of late type galaxies in nearby clusters with the aim to investigate the effects exerted by both the very local and the global cluster environments. We report new VLA-HI images of galaxies in Abell 1367 and study the evolution of their gaseous component. In Abell 85 we perform a deep NIR imaging survey of the brightest spirals projected up to 1.0 Abell radius with the aim of unveiling possible gravitational effects on their stellar disks. Here we show preliminary results of these projects, mainly focused on infalling compact groups of galaxies moving towards their respective cluster centers.

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.

Chromospheric activity in several single late-type stars

2015 ◽  
Vol 15 (2) ◽  
pp. 252-274 ◽  
Author(s):  
Li-Yun Zhang ◽  
Qing-Feng Pi ◽  
Zhong-Zhong Zhu
Keyword(s):  
Late Type ◽  
Chromospheric Activity

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.

scholarly journals THE CHROMOSPHERIC ACTIVITY OF [HH97] FS Aur-79: A CLOSE BINARY WITH LATE-TYPE ACTIVE (dK7e+dM3e) COMPONENTS

2011 ◽  
Vol 141 (4) ◽  
pp. 124 ◽  
Author(s):  
S. J. Austin ◽  
J. W. Robertson ◽  
T. R. de Souza ◽  
C. Tycner ◽  
R. K. Honeycutt
Keyword(s):  
Close Binary ◽  
Late Type ◽  
Chromospheric Activity

scholarly journals 12 years of stellar activity observations in Argentina

2011 ◽  
Vol 7 (S286) ◽  
pp. 317-323 ◽  
Author(s):  
P. J. D. Mauas ◽  
A. Buccino ◽  
R. Díaz ◽  
M. Vieytes ◽  
R. Petrucci ◽  
...  
Keyword(s):  
Spectral Range ◽  
Conversion Factor ◽  
Activity Levels ◽  
Late Type ◽  
Cyclic Activity ◽  
Chromospheric Activity ◽  
Activity Measurements ◽  
Radiative Losses ◽  
Hydrogen Lines ◽  
Observational Program

AbstractWe present an observational program we started in 1999, to systematically obtain mid-resolution spectra of late-type stars, to study in particular chromospheric activity. In particular, we found cyclic activity in four dM stars, including Prox-Cen. We directly derived the conversion factor that translates the known S index to flux in the Ca II cores, and extend its calibration to a wider spectral range. We investigated the relation between the activity measurements in the calcium and hydrogen lines, and found that the usual correlation observed is the product of the dependence of each flux on stellar color, and it is not always preserved when simultaneous observations of a particular star are considered. We also used our observations to model the chromospheres of stars of different spectral types and activity levels, and found that the integrated chromospheric radiative losses, normalized to the surface luminosity, show a unique trend for G and K dwarfs when plotted against the S index.

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
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