scholarly journals Mass - effective temperature - surface gravity relation for intermediate-mass main-sequence stars

2021 ◽  
Author(s):  
T. Kılıçoğlu
Keyword(s):  
Effective Temperature ◽  
Main Sequence ◽  
Surface Gravity ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Temperature Surface

scholarly journals IPHAS A-type Stars with Mid-IR Excesses in Spitzer Surveys

2009 ◽  
Vol 5 (H15) ◽  
pp. 815-815
Author(s):  
Antonio S. Hales ◽  
Michael J. Barlow ◽  
Janet E. Drew ◽  
Yvonne C. Unruh ◽  
Robert Greimel ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Main Sequence ◽  
Terrestrial Planet ◽  
Circumstellar Disks ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Mid Infrared ◽  
Isaac Newton ◽  
Intermediate Mass Stars ◽  
Dust Disks

AbstractThe Isaac Newton Photometric H-Alpha Survey (IPHAS) provides (r′-Hα)-(r′-i′) colors, which can be used to select AV0-5 Main Sequence star candidates (age~20-200 Myr). By combining a sample of 23050 IPHAS-selected A-type stars with 2MASS, GLIMPSE and MIPSGAL photometry we searched for mid-infrared excesses attributable to dusty circumstellar disks. Positional cross-correlation yielded a sample of 2692 A-type stars, of which 0.6% were found to have 8-μm excesses above the expected photospheric values. The low fraction of main sequence stars with mid-IR excesses found in this work indicates that dust disks in the terrestrial planet zone of Main Sequence intermediate mass stars are rare. Dissipation mechanisms such as photo-evaporation, grain growth, collisional grinding or planet formation could possibly explain the depletion of dust detected in the inner regions of these disks.

Angular momentum transport in pre-main-sequence stars of intermediate mass

Solar Physics ◽  
1990 ◽  
Vol 128 (1) ◽  
pp. 287-298 ◽  
Author(s):  
C. Vigneron ◽  
A. Mangeney ◽  
C. Catala ◽  
E. Schatzman
Keyword(s):  
Angular Momentum ◽  
Main Sequence ◽  
Momentum Transport ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Angular Momentum Transport

scholarly journals Small and Intermediate Mass Stellar Evolution - Main Sequence and Close to It

1993 ◽  
Vol 137 ◽  
pp. 410-425 ◽  
Author(s):  
A. Noels ◽  
N. Grevesse
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Turbulent Diffusion ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Physical Mechanisms ◽  
Standard Models

AbstractWe present the standard models for small and intermediate main sequence stars and we discuss some of the problems arising with semiconvection and overshooting. The surface abundance of Li serves as a test for other physical mechanisms, including microscopic and turbulent diffusion, rotation and mass loss.

Stellar Parameterisation using KPCA and SVM

2017 ◽  
Vol 14 (S339) ◽  
pp. 345-348
Author(s):  
H. Yuan ◽  
Y. Zhang ◽  
Y. Lei ◽  
Y. Dong ◽  
Z. Bai ◽  
...  
Keyword(s):  
Effective Temperature ◽  
Hybrid Approach ◽  
Principal Component ◽  
Test Sample ◽  
Surface Gravity ◽  
Kernel Principal Component Analysis ◽  
Support Vector ◽  
Stellar Spectra ◽  
The Impact ◽  
Temperature Surface

AbstractWith so many spectroscopic surveys, both past and upcoming, such as SDSS and LAMOST, the number of accessible stellar spectra is continuously increasing. There is therefore a great need for automated procedures that will derive estimates of stellar parameters. Working with spectra from SDSS and LAMOST, we put forward a hybrid approach of Kernel Principal Component Analysis (KPCA) and Support Vector Machine (SVM) to determine the stellar atmospheric parameters effective temperature, surface gravity and metallicity. For stars with both APOGEE and LAMOST spectra, we adopt the LAMOST spectra and APOGEE parameters, and then use KPCA to reduce dimensionality and SVM to measure parameters. Our method provides reliable and precise results; for example, the standard deviation of effective temperature, surface gravity and metallicity for the test sample come to approximately 47–75 K, 0.11–0.15 dex and 0.06–0.075 dex, respectively. The impact of the signal:noise ratio of the observations upon the accuracy of the results is also investigated.

scholarly journals A Spectroscopic Study of Blue Stragglers in M67

2008 ◽  
Vol 4 (S252) ◽  
pp. 391-397
Author(s):  
G. Q. Liu ◽  
L. Deng ◽  
M. Chávez ◽  
E. Bertone
Keyword(s):  
Effective Temperature ◽  
Spectral Properties ◽  
Main Sequence ◽  
Open Cluster ◽  
Observational Constraints ◽  
Photometric System ◽  
Main Sequence Stars ◽  
Complete Sample ◽  
Blue Stragglers ◽  
Fitting Method

AbstractSpectrophotometric observations of the complete sample of twenty four blue stragglers (BSs) in the old galactic open cluster M67 (NGC2682) have been collected, using the Guillermo Haro Observatory in Cananea, Mexico. All the calibrated spectra were re-calibrated by the Beijing Arizona Taipei Connecticut (BATC) photometric system which includes fluxes in 11 photometric bands covering ~3600–10000 Å. The goal of the current work is to provide observational constraints on spectral properties of BSs by determining the effective temperature (Teff) and surface gravity (log g). The overall results, obtained by applying the flux fitting method, indicate that Teff and surface gravities of BSs in M67 are fully compatible with those expected for main sequence stars.

scholarly journals Discovery of fossil magnetic fields in the intermediate-mass pre-main sequence stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 445-446
Author(s):  
Evelyne Alecian ◽  
Gregg A. Wade ◽  
Claude Catala
Keyword(s):  
Magnetic Fields ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Lower Mass ◽  
Convective Core

AbstractIt is now well-known that the surface magnetic fields observed in cool, lower-mass stars on the main sequence (MS) are generated by dynamos operating in their convective envelopes. However, higher-mass stars (above 1.5 M⊙) pass their MS lives with a small convective core and a largely radiative envelope. Remarkably, notwithstanding the absence of energetically-important envelope convection, we observe very strong (from 300 G to 30 kG) and organised (mainly dipolar) magnetic fields in a few percent of the A and B-type stars on the MS, the origin of which is not well understood. In this poster we propose that these magnetic fields could be of fossil origin, and we present very strong observational results in favour of this proposal.

scholarly journals Testing the companion hypothesis for the origin of the X-ray emission from intermediate-mass main-sequence stars

2006 ◽  
Vol 452 (3) ◽  
pp. 1001-1010 ◽  
Author(s):  
B. Stelzer ◽  
N. Huélamo ◽  
G. Micela ◽  
S. Hubrig
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
X Ray

scholarly journals An Improvement in the Visual Surface Brightness Scale for B5-F5 Main Sequence Stars

1985 ◽  
Vol 111 ◽  
pp. 523-524
Author(s):  
L. Pastori ◽  
G. Malaspina
Keyword(s):  
Surface Brightness ◽  
Color Index ◽  
Main Sequence ◽  
Surface Gravity ◽  
Main Sequence Stars ◽  
Interferometric Method ◽  
Gravity Effects ◽  
Good Agreement ◽  
Angular Diameters

Angular diameters of 593 B5-F5 main sequence stars listed in the “Catalogue of apparent diameters and absolute radii of stars” (CADARS; Fracassini et al. 1981) have been analysed in order to improve the precision of the visual surface brightness Sv. The new relations between this quantity and the color index (B-V)o turn out to be in good agreement with those found with the interferometric method (Barnes et al. 1978). Moreover, the results suggest that surface gravity effects may bias the Sv-(B-V)o relations.

scholarly journals RAVE-Gaia and the impact on Galactic archeology

2017 ◽  
Vol 12 (S330) ◽  
pp. 176-180
Author(s):  
Andrea Kunder
Keyword(s):  
Radial Velocity ◽  
Effective Temperature ◽  
Milky Way ◽  
Radial Velocities ◽  
Surface Gravity ◽  
Individual Stars ◽  
Dynamic Analyses ◽  
Data Release ◽  
The Impact ◽  
Temperature Surface

AbstractThe new data release (DR5) of the RAdial Velocity Experiment (RAVE) includes radial velocities of 520,781 spectra of 457,588 individual stars, of which 215,590 individual stars are released in the Tycho-Gaia astrometric solution (TGAS) in Gaia DR1. Therefore, RAVE contains the largest TGAS overlap of the recent and ongoing Milky Way spectroscopic surveys. Most of the RAVE stars also contain stellar parameters (effective temperature, surface gravity, overall metallicity), as well as individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni. Combining RAVE with TGAS brings the uncertainties in space velocities down by a factor of 2 for stars in the RAVE volume – 10 km s−1 uncertainties in space velocities are now able to be derived for the majority (70%) of the RAVE-TGAS sample, providing a powerful platform for chemo-dynamic analyses of the Milky Way. Here we discuss the RAVE-TGAS impact on Galactic archaeology as well as how the Gaia parallaxes can be used to break degeneracies within the RAVE spectral regime for an even better return in the derivation of stellar parameters and abundances.

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