scholarly journals An Increase in Small-planet Occurrence with Metallicity for Late-type Dwarf Stars in the Kepler Field and Its Implications for Planet Formation

2020 ◽  
Vol 160 (6) ◽  
pp. 253
Author(s):  
Cicero X. Lu ◽  
Kevin C. Schlaufman ◽  
Sihao Cheng
Keyword(s):  
Planet Formation ◽  
Late Type ◽  
Dwarf Stars

X‐Ray Spectroscopy of Rapidly Rotating, Late‐Type Dwarf Stars

1999 ◽  
Vol 512 (2) ◽  
pp. 874-891 ◽  
Author(s):  
K. P. Singh ◽  
S. A. Drake ◽  
E. V. Gotthelf ◽  
N. E. White
Keyword(s):  
Late Type ◽  
Dwarf Stars ◽  
X Ray

scholarly journals Lithium Abundance in Late-Type Stars

2000 ◽  
Vol 198 ◽  
pp. 368-369
Author(s):  
L Pompéia ◽  
B Barbuy ◽  
M. Grenon
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Detailed Analysis ◽  
Absolute Magnitude ◽  
Late Type ◽  
Lithium Abundance ◽  
Dwarf Stars ◽  
The Absolute

We have a list of nearby bulge-like turnoff stars with metallicities in the range −0.3 ≤ [Fe/H] ≤ +0.6, for which we have the absolute magnitude from Hipparcos, Geneva photometry (therefore temperature and metallicity), and radial velocity from Coravel (Grenon 1990, 1997). From Hipparcos data, the turnoff of these field stars indicate an age of 10-11 Gyr, which would be the age of the most metal-rich component of the bulge.We obtained high resolution échelle spectra with FEROS, with the aim to carry out detailed analysis of these stars. In this paper we present the Li abundance for 40 of these metal-rich and old dwarf stars, as a function of their temperatures.

scholarly journals Detecting activity cycles of late-type dwarfs in Kepler data

2013 ◽  
Vol 9 (S302) ◽  
pp. 224-227
Author(s):  
Krisztián Vida ◽  
Katalin Oláh
Keyword(s):  
Active Region ◽  
Frequency Analysis ◽  
Rotation Period ◽  
Light Curves ◽  
Late Type ◽  
Dwarf Stars ◽  
Time Frequency ◽  
Activity Cycles ◽  
Using Data ◽  
Fast Rotating

AbstractUsing data of fast-rotating active dwarf stars in the Kepler database, we perform time-frequency analysis of the light curves in order to search for signs of activity cycles. We use the phenomenon that the active region latitudes vary with the cycle (like the solar butterfly diagram), which causes the observed rotation period to change as a consequence of differential rotation. We find cycles in 8 cases of the 39 promising targets with periods between of 300–900 days.

Infrared Observations of Late-Type Dwarf Stars

1974 ◽  
Vol 86 ◽  
pp. 989 ◽  
Author(s):  
Bernard W. Bopp ◽  
R. D. Gehrz ◽  
J. A. Hackwell
Keyword(s):  
Late Type ◽  
Dwarf Stars ◽  
Infrared Observations

Observations of magnetic fields on two late-type dwarf stars

1980 ◽  
Vol 236 ◽  
pp. L155 ◽  
Author(s):  
R. D. Robinson ◽  
S. P. Worden ◽  
J. W. Harvey
Keyword(s):  
Magnetic Fields ◽  
Late Type ◽  
Dwarf Stars

scholarly journals On the Stellar Rotation-Activity Connection

1983 ◽  
Vol 102 ◽  
pp. 279-300 ◽  
Author(s):  
Robert Rosner
Keyword(s):  
Surface Activity ◽  
Rotation Rate ◽  
Late Type ◽  
Stellar Rotation ◽  
Dwarf Stars ◽  
X Ray

I discuss the connection between the rotation rate of late-type dwarf stars and their level of surface “activity” (as deduced from visible, UV, and X-ray observations) from both theoretical and observational perspectives.

scholarly journals 35. Stellar Constitution

1985 ◽  
Vol 19 (1) ◽  
pp. 479-502
Author(s):  
A. N. Cox ◽  
D. Sugimoto ◽  
P. H. Bodenheimer ◽  
C. S. Chiosi ◽  
D. J. Faulkner ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
Massive Stars ◽  
Structure Stability ◽  
Current Interest ◽  
Late Type ◽  
Dwarf Stars ◽  
Entire Field ◽  
Stellar Formation ◽  
Central Stars

This report of Commission 35, as in past reports, consists of some details of only a few selected topics. This is necessary because a survey of the entire field of stellar formation, structure, stability, evolution, pulsation, and explosions for the three year period from mid-1981 to mid-1984 would be excessively long. Our topics here, in order from the most massive stellar classes to the least are: Massive Stars (R.M. Humphreys), Rotation in Late Type Stars (W. Benz), Helioseismology (J. Christensen-Dalsgaard), Planetary Nebula Central Stars (E.M. Sion), Pulsations in Hot Degenerate Dwarf Stars (A.N. Cox and S.D. Kawaler), and White Dwarfs (V. Weidemann). There is some overlap in the reviewing of these last three reports because the topics are very closely related. Concentration in this dying stage of stellar evolution seems appropriate because of the great current interest in these matters.

scholarly journals Stellar Winds and Coronae in Cool Stars

1980 ◽  
Vol 51 ◽  
pp. 279-291 ◽  
Author(s):  
A.K. Dupree ◽  
L. Hartmann
Keyword(s):  
Theoretical Models ◽  
Stellar Winds ◽  
Late Type ◽  
Dwarf Stars ◽  
Giant Stars ◽  
Cool Stars ◽  
Thermally Driven ◽  
Effective Temperatures ◽  
Hot Corona ◽  
Theoretical Results

AbstractRecent observational and theoretical results are reviewed that pertain to the presence and characteristics of stellar coronae and winds in late-type stars. It is found that stars - principally dwarfs - exist with “hot” coronae similar to the Sun with thermally driven winds. For stars, at the lowest effective temperatures, and gravities characteristic of supergiant and giant stars, high temperature (~105K) atmospheres are absent (or if present are substantially weaker than in the dwarf stars), and massive winds are present. There also exist “hybrid” examples - luminous stars possessing both a “hot” corona and a supersonic stellar wind. Constraints for theoretical models are discussed.

scholarly journals High S/N Na I D Line Profiles in Late-Type MS Stars and their Importance for Stellar Modelling

1993 ◽  
Vol 137 ◽  
pp. 190-192 ◽  
Author(s):  
E. Covino ◽  
M.T. Gomez ◽  
G. Severino ◽  
M. Franchini
Keyword(s):  
High Resolution ◽  
Synthesis Method ◽  
Atomic Data ◽  
Line Profiles ◽  
Late Type ◽  
Stellar Spectrum ◽  
Dwarf Stars ◽  
Observational Techniques ◽  
Numerical Fit

Progress in observational techniques (i.e. high S/N spectroscopy) and modelling (e.g. RE models including convection, nonLTE codes, accurate atomic data) make significant to carry to extremes the numerical fit of a portion of the stellar spectrum and try to interpret the residual differences between calculations and observations in terms of stellar characteristics new respect to the employed model.We have started to apply this synthesis method to a set of high resolution, high S/N spectra of late-type dwarfs in the region of the Na I D lines, obtained at ESO with the 1.4m CAT on May 1989 (Franchini et al. 1992). The dwarf stars are modelled in radiative equilibrium (RE), and the Na I D line synthesis accounts for nonLTE and blend effects.

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