Galactic Infrared Astronomy

1971 ◽  
Vol 2 (1) ◽  
pp. 14-20 ◽  
Author(s):  
A. R. Hyland
Keyword(s):  
Interstellar Extinction ◽  
Infrared Astronomy ◽  
The Sun ◽  
Late Type ◽  
Infrared Observations ◽  
Effective Temperatures

Until the last six years few infrared observations of astronomical objects (other than the Sun and planets) had been attempted. Those few were primarily concerned with obtaining bolometric corrections and effective temperatures, the variation of bolometric magnitudes of late-type variables, and the derivation of the laws of interstellar extinction.

scholarly journals Surface gravity and effective temperature of the K5 subdwarf G 224-58 A and Arcturus from the fits to Ti and MgH lines

2016 ◽  
Vol 6 (1) ◽  
pp. 16-19
Author(s):  
I. Kushniruk ◽  
Ya. Pavlenko ◽  
M. Gálvez-Ortiz ◽  
Z. Zhang
Keyword(s):  
The Sun ◽  
Late Type ◽  
Selected Lines ◽  
Synthetic Spectra ◽  
Self Consistent ◽  
Minimization Procedure ◽  
Effective Temperatures ◽  
Red Giant ◽  
Consistent Approach

We discuss here the results obtained in the determination of effective temperatures and metallicities of late-type stars. We provide the abundances of MgH, TiI and TiII, with a list of selected lines, for the red giant of Arcturus and the metal-poor K subdwarf G 224-58 A. The Sun was used as a template star. After computing synthetic spectra for model atmospheres with different Teff and logg values, we used minimization procedures to determine the best fits to the observed features. The determination of Ti abundances was carried out in the framework of a self-consistent approach developed by Pavlenko et al. (2012). In the case of MgH we used similar minimization procedure. We present here the combination of two different approaches based on the fits performed to Ti and MgH, respectively. The resulting effective temperatures are Teff=4300 K for Arcturus and Teff=4600 K for G 224-58 A, where both solutions are degenerated with logg.

A Search for Dyson Spheres around Late-Type Stars in the Solar Neighborhood II

1997 ◽  
Vol 161 ◽  
pp. 707-709 ◽  
Author(s):  
Jun Jugaku ◽  
Shiro Nishimura
Keyword(s):  
Solar Neighborhood ◽  
The Sun ◽  
Late Type ◽  
Solar Type

AbstractWe continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

scholarly journals IUE Observations of the Chromospheric Activity-Age Relation in Young Solar-Type Stars

1983 ◽  
Vol 102 ◽  
pp. 161-164
Author(s):  
Theodore Simon ◽  
Ann Merchant Boesgaard
Keyword(s):  
Magnetic Fields ◽  
Flare Activity ◽  
The Sun ◽  
Late Type ◽  
Cool Star ◽  
Opportune Time ◽  
Solar Type ◽  
Age Relation ◽  
Relationship Of ◽  
The Relationship

The difficulties of measuring magnetic fields in late-type stars other than the sun are well known, as one is reminded by other contributions to these Proceedings. This Symposium nevertheless comes at a very opportune time, as we are now at the point where we can begin to explore the relationship of stellar magnetism to flare activity and quiescent cool star chromospheres, transition regions (TRs), and coronae.

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

scholarly journals Stellar Abundance Analyses in the Light of 3D Hydrodynamical Model Atmospheres

2003 ◽  
Vol 210 ◽  
pp. 273-286 ◽  
Author(s):  
Martin Asplund
Keyword(s):  
Recent Progress ◽  
Hydrodynamical Model ◽  
Observational Constraints ◽  
The Sun ◽  
Mixing Length ◽  
Line Formation ◽  
Late Type ◽  
Line Shapes ◽  
Free Parameters

I describe recent progress in terms of 3D hydrodynamical model atmospheres and 3D line formation and their applications to stellar abundance analyses of late-type stars. Such 3D studies remove the free parameters inherent in classical 1D investigations (mixing length parameters, macro- and microturbulence) yet are highly successful in reproducing a large arsenal of observational constraints such as detailed line shapes and asymmetries. Their potential for abundance analyses is illustrated by discussing the derived oxygen abundances in the Sun and in metal-poor stars, where they seem to resolve long-standing problems as well as significantly alter the inferred conclusions.

scholarly journals Chromospheric Surface Structures on EI Eridani and HD 199178

1991 ◽  
Vol 130 ◽  
pp. 330-332
Author(s):  
James E. Neff
Keyword(s):  
Spatial Distribution ◽  
Effective Temperature ◽  
Three Dimensional ◽  
Stellar Atmospheres ◽  
Surface Structures ◽  
High Dispersion ◽  
The Sun ◽  
Late Type ◽  
Magnetic Topology ◽  
Radial Dimension

Several groups at this meeting are presenting maps of the spatial distribution of either brightness or effective temperature in the photospheres of rapidly-rotating, late-type stars. It is generally believed that structure seen in these maps traces the magnetic topology, in analogy with the Sun. We expect the structure of the outer atmospheres (i.e., chromosphere and corona) of these stars to be even more directly tied to the magnetic topology; the magnetic structure is three-dimensional. In order to probe the radial dimension of stellar atmospheres, we need to combine maps of the spatial distribution of emission from chromospheres and coronae with these detailed photospheric maps.Along with collaborators at Armagh, Catania, Boulder, Paris, Helsinki, and Stony Brook, I have been obtaining high-dispersion ultraviolet spectra of several rapidly-rotating, late-type stars using the IUE spacecraft. I discuss results for two stars, El Eridani and HD 199178, for which photospheric maps are presented elsewhere at this conference.

scholarly journals Hunting for Stellar Coronal Mass Ejections

2016 ◽  
Vol 12 (S328) ◽  
pp. 198-203
Author(s):  
Heidi Korhonen ◽  
Krisztián Vida ◽  
Martin Leitzinger ◽  
Petra Odert ◽  
Orsolya Eszter Kovács
Keyword(s):  
Time Series ◽  
Coronal Mass Ejections ◽  
Detection Probability ◽  
Open Clusters ◽  
Occurrence Rate ◽  
Archival Data ◽  
The Sun ◽  
Late Type ◽  
Optical Telescope ◽  
Balmer Lines

AbstractCoronal mass ejections (CMEs) are explosive events that occur basically daily on the Sun. It is thought that these events play a crucial role in the angular momentum and mass loss of late-type stars, and also shape the environment in which planets form and live. Stellar CMEs can be detected in optical spectra in the Balmer lines, especially in Hα, as blue-shifted extra emission/absorption. To increase the detection probability one can monitor young open clusters, in which the stars are due to their youth still rapid rotators, and thus magnetically active and likely to exhibit a large number of CMEs. Using ESO facilities and the Nordic Optical Telescope we have obtained time series of multi-object spectroscopic observations of late-type stars in six open clusters with ages ranging from 15 Myrs to 300 Myrs. Additionally, we have studied archival data of numerous active stars. These observations will allow us to obtain information on the occurrence rate of CMEs in late-type stars with different ages and spectral types. Here we report on the preliminary outcome of our studies.

scholarly journals Method to estimate the effective temperatures of late-type giants using line-depth ratios in the wavelength range 0.97–1.32 μm

2017 ◽  
Vol 473 (4) ◽  
pp. 4993-5001 ◽  
Author(s):  
Daisuke Taniguchi ◽  
Noriyuki Matsunaga ◽  
Naoto Kobayashi ◽  
Kei Fukue ◽  
Satoshi Hamano ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Late Type ◽  
Effective Temperatures ◽  
Line Depth
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