scholarly journals High-resolution spectroscopy of detached solar-type eclipsing binaries observed during the Kepler K2 mission

2020 ◽  
Vol 493 (2) ◽  
pp. 2329-2338
Author(s):  
B Hoyman ◽  
Ö Çakırlı
Keyword(s):  
Theoretical Models ◽  
Eclipsing Binaries ◽  
High Resolution Spectroscopy ◽  
Physical Parameters ◽  
Evolutionary Status ◽  
Low Mass Stars ◽  
Ongoing Effort ◽  
Stellar Parameter ◽  
Solar Type ◽  
Low Mass

ABSTRACT Solar-type stars in eclipsing binaries are proving to be a remarkable resource of knowledge for testing models of stellar evolution, as spectroscopic and photometric studies have opened up a window into their interiors. Until recently, many cases have been worked out with Kepler data. In an ongoing effort to elucidate this research, we examine five detached eclipsing binaries, selected from the Kepler catalogue. There is a well-known stellar parameter discrepancy for low-mass stars, in that the observed radii and masses are often larger and stars overluminous than predicted by theory by several per cent. In our samples, we found five double-lined binaries, with solar-type stars dominating the spectrum. The orbital and light-curve solutions were found for them, and compared with isochrones, in order to estimate absolute physical parameters and evolutionary status of the components. An important aspect of this work is that the calculated stellar radii and masses are consistent with theoretical models within the uncertainties, whereas the estimated temperatures from the disentangled spectra of the components are no different than predicted.

scholarly journals Evolution Of The Lithium Abundances Of Solar-Type Stars. IX. High-Resolution Spectroscopy of Low-Mass Stars in NGC 2264

1999 ◽  
Vol 118 (3) ◽  
pp. 1301-1314 ◽  
Author(s):  
David R. Soderblom ◽  
Jeremy R. King ◽  
Lionel Siess ◽  
Burton F. Jones ◽  
Debra Fischer
Keyword(s):  
High Resolution ◽  
High Resolution Spectroscopy ◽  
Low Mass Stars ◽  
Solar Type ◽  
Low Mass

scholarly journals Recovering variable stars in large surveys: EAup Algol-type class in the Catalina Survey

2020 ◽  
Vol 498 (2) ◽  
pp. 2833-2844
Author(s):  
A Carmo ◽  
C E Ferreira Lopes ◽  
A Papageorgiou ◽  
F J Jablonski ◽  
C V Rodrigues ◽  
...  
Keyword(s):  
Binary Systems ◽  
Optimization Procedure ◽  
Theoretical Models ◽  
Variable Stars ◽  
Eclipsing Binaries ◽  
Low Mass Stars ◽  
Monte Carlo Optimization ◽  
Low Mass ◽  
Unknown Period

ABSTRACT The discovery and characterization of Algol eclipsing binaries (EAs) provide an opportunity to contribute for a better picture of the structure and evolution of low-mass stars. However, the cadence of most current photometric surveys hinders the detection of EAs since the separation between observations is usually larger than the eclipse(s) duration and hence few measurements are found at the eclipses. Even when those objects are detected as variable, their periods can be missed if an appropriate oversampling factor is not used in the search tools. In this paper, we apply this approach to find the periods of stars catalogued in the Catalina Real-Time Transient Survey (CRTS) as EAs having unknown period (EAup). As a result, the periods of ${\sim} 56{\rm {per \, cent}}$ of them were determined. Eight objects were identified as low-mass binary systems and modelled with the Wilson & Devinney synthesis code combined with a Markov chain Monte Carlo optimization procedure. The computed masses and radii are in agreement with theoretical models and show no evidence of inflated radii. This paper is the first of a series aiming to identify suspected binary systems in large surveys.

scholarly journals Exploring Flaring Behaviour on Low Mass Stars, Solar-type Stars and the Sun

2019 ◽  
Vol 15 (S354) ◽  
pp. 384-391
Author(s):  
L. Doyle ◽  
G. Ramsay ◽  
J. G. Doyle ◽  
P. F. Wyper ◽  
E. Scullion ◽  
...  
Keyword(s):  
High Energy ◽  
The Sun ◽  
Low Mass Stars ◽  
Highly Active ◽  
Rotation Phase ◽  
Solar Type ◽  
Low Mass ◽  
Insight Into ◽  
Reconnection Model ◽  
High Cadence

AbstractWe report on our project to study the activity in both the Sun and low mass stars. Utilising high cadence, Hα observations of a filament eruption made using the CRISP spectropolarimeter mounted on the Swedish Solar Telescope has allowed us to determine 3D velocity maps of the event. To gain insight into the physical mechanism which drives the event we have qualitatively compared our observation to a 3D MHD reconnection model. Solar-type and low mass stars can be highly active producing flares with energies exceeding erg. Using K2 and TESS data we find no correlation between the number of flares and the rotation phase which is surprising. Our solar flare model can be used to aid our understanding of the origin of flares in other stars. By scaling up our solar model to replicate observed stellar flare energies, we investigate the conditions needed for such high energy flares.

Twin stars as tracers of binary evolution in the Kepler era

2021 ◽  
Author(s):  
Sara Bulut ◽  
Baris Hoyman ◽  
Ahmet Dervisoglu ◽  
Orkun Özdarcan ◽  
Ömür Cakilrli
Keyword(s):  
High Resolution ◽  
Internal Structure ◽  
Spectroscopic Analysis ◽  
Independent Method ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Evolutionary Status ◽  
Mass Ratio ◽  
Orbital Parameters ◽  
Binary Evolution

Abstract We present results of the combined photometric and spectroscopic analysis of four systems, which are eclipsing binaries with a twin–component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high–resolution optical spectra to calculate the radial velocities and later combined them with photometry to derive orbital parameters. Temperatures and metallicities of systems were estimated from high-resolution spectra. For each binary, we obtained a full set of orbital and physical parameters, reaching precision below 3 per cent in masses and radii for whole pairs. By comparing our results with PARSEC and MIST isochrones, we assess the distance, age and evolutionary status of the researched objects. The primary and/or secondary stars of EPIC 216075815 and EPIC 202843107 are one of the cases where asteroseismic parameters of δ Sct and γ Dor pulsators were confirmed by an independent method and rare examples of the twin–eclipsing binaries, therefore the following analyses and results concern the pulsating nature of the components.

scholarly journals Multi-Wavelength High-Resolution Spectroscopy for Exoplanet Detection: Motivation, Instrumentation and First Results

Geosciences ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 289 ◽  
Author(s):  
Serena Benatti
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Giant Planet ◽  
High Resolution Spectroscopy ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
First Results ◽  
Multi Wavelength ◽  
Low Mass ◽  
Rocky Planets

Exoplanet research has shown an incessant growth since the first claim of a hot giant planet around a solar-like star in the mid-1990s. Today, the new facilities are working to spot the first habitable rocky planets around low-mass stars as a forerunner for the detection of the long-awaited Sun-Earth analog system. All the achievements in this field would not have been possible without the constant development of the technology and of new methods to detect more and more challenging planets. After the consolidation of a top-level instrumentation for high-resolution spectroscopy in the visible wavelength range, a huge effort is now dedicated to reaching the same precision and accuracy in the near-infrared. Actually, observations in this range present several advantages in the search for exoplanets around M dwarfs, known to be the most favorable targets to detect possible habitable planets. They are also characterized by intense stellar activity, which hampers planet detection, but its impact on the radial velocity modulation is mitigated in the infrared. Simultaneous observations in the visible and near-infrared ranges appear to be an even more powerful technique since they provide combined and complementary information, also useful for many other exoplanetary science cases.

scholarly journals The Evolutionary Status of Short-Period RS CVn and Related W UMa Eclipsing Binaries

1983 ◽  
Vol 71 ◽  
pp. 463-464 ◽  
Author(s):  
G. Russo ◽  
L. Milano ◽  
S. Mancuso
Keyword(s):  
Eclipsing Binaries ◽  
Evolutionary Status ◽  
Type Activity ◽  
Rs Cvn Stars ◽  
Short Period ◽  
Solar Type

Among the RS CVn stars showing solar-type activity, with spectral types ranging from F to K and total masses up to 4 M⊙, there are two peculiar groups with period less than one day:a)agroup with components well inside their Roche lobes (Short-Period-Group, hereinafter SPG) and b) a group with their components in a thin or marginal degree of contact, with lightcurves of W UMa-W type (hereinafter WWG).

Theoretical models of low-mass stars and brown dwarfs. I - The lower main sequence

1989 ◽  
Vol 342 ◽  
pp. 1003 ◽  
Author(s):  
Ben Dorman ◽  
Lorne A. Nelson ◽  
W. Y. Chau
Keyword(s):  
Main Sequence ◽  
Brown Dwarfs ◽  
Theoretical Models ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals Magnetic Activity of Two Similar Subgiants in Binaries with Very Different Mass Ratios: EI Eri and V711 Tau

2011 ◽  
Vol 7 (S282) ◽  
pp. 478-479 ◽  
Author(s):  
Katalin Oláh ◽  
Zsolt Kővári ◽  
Krisztián Vida ◽  
Klaus G. Strassmeier
Keyword(s):  
Differential Rotation ◽  
Activity Patterns ◽  
Magnetic Activity ◽  
Light Curves ◽  
Physical Parameters ◽  
Remarkable Difference ◽  
High Latitudes ◽  
Solar Type ◽  
Low Mass ◽  
Fast Rotating

AbstractWe use more than three decades-long photometry to study the activity patterns on the two fast-rotating subgiant components in EI Eri (G5IV) and V711 Tau (K1IV). From yearly mean rotational periods from the light curves, we find that EI Eri, with well-measured solar-type differential rotation, always has spots from the equator to high latitudes. The measured differential rotation of V711 Tau is controversial, and in any case is very small. The spots on the K1IV star in V711 Tau seem to be tidally locked. The physical parameters of the two systems are similar, with one remarkable difference: EI Eri has a low mass M4-5 dwarf companion, whereas V711 Tau has a G5V star in the system, thus their mass centers are in very different positions. This may modify the whole internal structure of the active stars, causing marked differences in their surface features.

scholarly journals The rotation of very low-mass stars and brown dwarfs

2007 ◽  
Vol 3 (S243) ◽  
pp. 241-248
Author(s):  
Jochen Eislöffel ◽  
Alexander Scholz
Keyword(s):  
Angular Momentum ◽  
Brown Dwarfs ◽  
Magnetic Interaction ◽  
Stellar Winds ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Angular Momentum Loss ◽  
Rotational Evolution ◽  
Solar Type ◽  
Low Mass

AbstractThe evolution of angular momentum is a key to our understanding of star formation and stellar evolution. The rotational evolution of solar-mass stars is mostly controlled by magnetic interaction with the circumstellar disc and angular momentum loss through stellar winds. Major differences in the internal structure of very low-mass stars and brown dwarfs – they are believed to be fully convective throughout their lives, and thus should not operate a solar-type dynamo – may lead to major differences in the rotation and activity of these objects. Here, we report on observational studies to understand the rotational evolution of the very low-mass stars and brown dwarfs.

scholarly journals Infalling Streamer-Disk-Outflow System in a Nearby High-mass Star Formation Region

2021 ◽  
Author(s):  
Xi Chen ◽  
Zhiyuan Ren ◽  
Da-Lei Li ◽  
Tie Liu ◽  
Ke Wang ◽  
...  
Keyword(s):  
Direct Detection ◽  
Theoretical Models ◽  
Young Stellar Objects ◽  
High Mass ◽  
Similar Process ◽  
Mass Star ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Stellar Objects ◽  
Low Mass

Abstract Theoretical models and numerical simulations suggest that high mass star (with mass > 8 solar mass) can be formed either via monolithic collapse of a massive core or competitive accretion, but the dominant mechanism is currently unclear. Although recent high resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have detected physical and kinematic features, such as disks, outflows and filamentary structures surrounding the high mass young stellar objects (HMYSO), direct detection of the infalling gas towards the HMYSO is still the key to distinguish the different scenarios. Chemically fresh gas inflows have been detected towards low-mass stars being formed, which are consistent with the accretion-disk-outflow process. In this work we report the detection of a chemically fresh inflow which is feeding HMYSO growth in the nearby high mass star-forming region G352.63-1.07. High quality images of the dust and molecular lines from both ALMA and the Submillimeter Array (SMA) have consistently revealed a gravitationally-controlled gas inflow towards a rotating structure (disk or torus) around the HMYSO. The HMYSO is also observed to have an outflow, but it can be clearly separated from the inflow. These kinematic features provide observational evidence to support the conjecture that high-mass stars can be formed in a similar process to that observed in the low-mass counterparts. The chemically fresh infalling streamers could also be related with the disk configuration, fragmentation and accretion bursts that occur in both simulations and observations.

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