arXiv: Solar and Stellar Astrophysics最新文献_第5页

Long-term photospheric instabilities and envelopes dynamics in the post-AGB binary system 89 Herculis 后agb双星系统89大力神的长期光球不稳定性和包层动力学

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-19 DOI: 10.1093/mnras/staa3255

M. Gangi, M. Giarrusso, Matteo Munari, C. Ferrara, C. Ferrara, C. Scalia, C. Scalia, F. Leone, F. Leone

{"title":"Long-term photospheric instabilities and envelopes dynamics in the post-AGB binary system 89 Herculis","authors":"M. Gangi, M. Giarrusso, Matteo Munari, C. Ferrara, C. Ferrara, C. Scalia, C. Scalia, F. Leone, F. Leone","doi":"10.1093/mnras/staa3255","DOIUrl":"https://doi.org/10.1093/mnras/staa3255","url":null,"abstract":"We present a long-term optical spectroscopic study of the post-AGB binary system 89 Herculis, with the aim to characterize the relationship between photospheric instabilities and dynamics in the close circumstellar environment of the system. This study is based on spectra acquired with the high-resolution Catania Astrophysical Observatory Spectropolarimeter and archive data, covering a time interval between 1978 and 2018. We find long-term changes in the radial velocity curve of the system, occurring mostly in amplitude, which correlate with the variability observed in the blue-shifted absorption component of the P Cygni like H$alpha$ profile. Two possible scenarios are discussed. We also find strong splitting in the s-process elements of ion{Ba}{ii} $6141.713$ A and $6496.898$ A,lines, with short-term morphological variations. A Gaussian decomposition of such profiles allows us to distinguish four shell components, two expanding and two in-falling toward the central star, which are subject to the orbital motion of the system and are not affected by the long-term instabilities. Finally, we find that the numerous metal lines in emission could originate in regions of a structured circumbinary disk that have sizes proportional to the energy of the corresponding upper level transition $rm E_{up}$. This study demonstrates the potential of long-term high-resolution spectroscopy in linking together the instability processes occurring during the late evolutionary stages of post-AGBs and the subsequent phase of PNe.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87002417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A STUDY OF THE TIME VARIABILITY AND LINE PROFILE VARIATIONS OF κ DRA κ dra的时间变异性和线形变化的研究

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-18 DOI: 10.22201/IA.01851101P.2021.57.01.06

S. Saad, M. Nouh, A. Shokry, I. Zead

引用次数: 2

Power spectrum of turbulent convection in the solar photosphere 太阳光球中湍流对流的功率谱

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-18 DOI: 10.1051/0004-6361/202037545

L. Y. Chaouche, R. Cameron, S. Solanki, T. Riethmuller, L. S. Anusha, V. Witzke, A. Shapiro, P. Barthol, A. Gandorfer, L. Gizon, J. Hirzberger, M. Noort, J. Rodr'iguez, J. C. D. T. Iniesta, D. O. Su'arez, W. Schmidt, V. Pillet, M. Knolker

{"title":"Power spectrum of turbulent convection in the solar photosphere","authors":"L. Y. Chaouche, R. Cameron, S. Solanki, T. Riethmuller, L. S. Anusha, V. Witzke, A. Shapiro, P. Barthol, A. Gandorfer, L. Gizon, J. Hirzberger, M. Noort, J. Rodr'iguez, J. C. D. T. Iniesta, D. O. Su'arez, W. Schmidt, V. Pillet, M. Knolker","doi":"10.1051/0004-6361/202037545","DOIUrl":"https://doi.org/10.1051/0004-6361/202037545","url":null,"abstract":"The solar photosphere provides us with a laboratory for understanding turbulence in a layer where the fundamental processes of transport vary rapidly and a strongly superadiabatic region lies very closely to a subadiabatic layer. Our tools for probing the turbulence are high-resolution spectropolarimetric observations such as have recently been obtained with the two sunrise missions, and numerical simulations. Our aim is to study photospheric turbulence with the help of Fourier power spectra that we compute from observations and simulations. We also attempt to explain some properties of the photospheric overshooting flow with the help of its governing equations and simulations. We find that quiet-Sun observations and smeared simulations exhibit a power-law behavior in the subgranular range of their Doppler velocity power spectra with an index of$~approx -2$. The unsmeared simulations exhibit a power-law index of$~approx -2.25$. The smearing considerably reduces the extent of the power-law-like portion of the spectra. Therefore, the limited spatial resolution in some observations might eventually result in larger uncertainties in the estimation of the power-law indices. \u0000The simulated vertical velocity power spectra as a function of height show a rapid change in the power-law index from the solar surface to $300$~km above it. A scale-dependent transport of the vertical momentum occurs. At smaller scales, the vertical momentum is more efficiently transported sideways than at larger scales. This results in less vertical velocity power transported upward at small scales than at larger scales and produces a progressively steeper vertical velocity power law below $180$ km. Above this height, the gravity work progressively gains importance at all scales, making the atmosphere progressively more hydrostatic and resulting in a gradually less steep power law.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82375631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Detailed studies of IPHAS sources - I. The disrupted late bipolar IPHASX J193718.6+202102 IPHAS来源的详细研究——ⅰ。中断的晚期双相IPHASX J193718.6+202102

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-16 DOI: 10.1093/mnras/staa3270

L. Sabin, M. Guerrero, S. Zavala, J. Toalá, G. Ramos-Larios, V. G'omez-Llanos

{"title":"Detailed studies of IPHAS sources - I. The disrupted late bipolar IPHASX J193718.6+202102","authors":"L. Sabin, M. Guerrero, S. Zavala, J. Toalá, G. Ramos-Larios, V. G'omez-Llanos","doi":"10.1093/mnras/staa3270","DOIUrl":"https://doi.org/10.1093/mnras/staa3270","url":null,"abstract":"We present a detailed analysis of the new planetary nebula (PN) IPHASX J193718.6+202102 using deep imaging and intermediate- and high resolution spectroscopy that are interpreted through morpho-kinematic and photoionisation modelling. The physical structure of the nebula consists of a fragmented torus and an extremely faint orthogonal bipolar outflow, contrary to the pinched waist PN morphology suggested by its optical image. Our kinematic analysis indicates that the torus is expanding at 25$pm$5 km s$^{-1}$ and is gradually breaking up. At an estimated distance of 7.1$_{-0.3}^{+0.8}$ kpc, the corresponding kinematic age of $sim$26000 years is consistent with a faint and disintegrating PN. The intermediate-resolution spectra reveal an excited PN with chemical abundances typical of Type II PNe. Based on the latter we also estimate an initial mass for the progenitor in the range 2--3 M$_{odot}$ and a central star (CSPN) mass $M_mathrm{CSPN}sim$0.61 M$_{odot}$. The Spitzer MIPS 24 $mu$m emission that closely follows the fragmented torus could be attributed to the emission of [O IV] at 25.9 $mu$m rather than to dust emission. All the results coherently point towards an evolved moderately massive bipolar Type II PN on the brink of dissolving into the interstellar medium.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84106511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Interpretation of the power spectrum of the quiet Sun photospheric turbulence 解释安静太阳光球湍流的功率谱

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-15 DOI: 10.1093/mnras/staa3238

I. Goldman

引用次数: 2

Thorough characterisation of the 16 Cygni system 天鹅座16星系的彻底特征

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-13 DOI: 10.1051/0004-6361/202038522

M. Farnir, M. Dupret, G. Buldgen, S. Salmon, A. Noels, C. Pinccon, C. Pezzotti, P. Eggenberger

{"title":"Thorough characterisation of the 16 Cygni system","authors":"M. Farnir, M. Dupret, G. Buldgen, S. Salmon, A. Noels, C. Pinccon, C. Pezzotti, P. Eggenberger","doi":"10.1051/0004-6361/202038522","DOIUrl":"https://doi.org/10.1051/0004-6361/202038522","url":null,"abstract":"Context: Being part of the brightest solar-like stars, and close solar analogues, the 16 Cygni system is of great interest to the scientific community and may provide insight into the past and future evolution of our Sun. It has been observed thoroughly by the Kepler satellite, which provided us with data of an unprecedented quality. Aims: This paper is the first of a series aiming to extensively characterise the system. We test several choices of micro- and macro-physics to highlight their effects on optimal stellar parameters and provide realistic stellar parameter ranges. Methods: We used a recently developed method, WhoSGlAd, that takes the utmost advantage of the whole oscillation spectrum of solar-like stars by simultaneously adjusting the acoustic glitches and the smoothly varying trend. For each choice of input physics, we computed models which account, at best, for a set of seismic indicators that are representative of the stellar structure and are as uncorrelated as possible. The search for optimal models was carried out through a Levenberg-Marquardt minimisation. First, we found individual optimal models for both stars. We then selected the best candidates to fit both stars while imposing a common age and composition. Results: We computed realistic ranges of stellar parameters for individual stars. We also provide two models of the system regarded as a whole. We were not able to build binary models with the whole set of choices of input physics considered for individual stars as our constraints seem too stringent. We may need to include additional parameters to the optimal model search or invoke non-standard physical processes.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81368043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Differential rotation of the solar corona: A new data-adaptive multiwavelength approach 日冕的微分旋转:一种新的数据自适应多波长方法

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-13 DOI: 10.1051/0004-6361/202039094

S. Mancuso, S. Giordano, D. Barghini, D. Telloni

{"title":"Differential rotation of the solar corona: A new data-adaptive multiwavelength approach","authors":"S. Mancuso, S. Giordano, D. Barghini, D. Telloni","doi":"10.1051/0004-6361/202039094","DOIUrl":"https://doi.org/10.1051/0004-6361/202039094","url":null,"abstract":"For the purpose of investigating the differential rotation of the solar corona, we analyzed ultraviolet (UV) spectral line observations acquired on both the east and west limbs at 1.7 $R_{odot}$ by SOHO/UVCS during the solar minimum preceding solar cycle 23. To obtain a reliable and statistically robust picture of the rotational profile, we used a set of simultaneous 400-day long spectral line intensities of five different spectral lines: O VI 1032 A, O VI 1037 A, Si XII 499 A, Si XII 521 A, and H I 1216 A, which are routinely observed by UVCS. The data were analyzed by means of two different techniques: the generalized Lomb-Scargle periodogram (GLS) and a multivariate data-adaptive technique called multichannel singular spectrum analysis (MSSA). Among many other positive outcomes, this latter method is unique in its ability to recognize common oscillatory modes between the five time series observed at both limbs. The latitudinal rotation profile obtained in this work emphasizes that the low-latitude region of the UV corona (about $pm 20^{circ}$ from the solar equator) exhibits differential rotation, while the higher-latitude structures do rotate quasi-rigidly. The differential rotation rate of the solar corona as evinced at low-latitudes is consistent with the rotational profile of the near-surface convective zone of the Sun, suggesting that the rotation of the corona at 1.7 $R_{odot}$ is linked to intermediate-scale magnetic bipole structures anchored near 0.99 $R_{odot}$. The quasi-rigid rotation rate found at mid and high latitudes is instead attributed to the influence of large-scale coronal structures linked to the rigidly rotating coronal holes. We further suggest that the methodology presented in this paper could represent a milestone for future investigations on differential rotation rates when dealing with simultaneous multiwavelength data.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72854450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Simulations of multiple nova eruptions induced by wind accretion in symbiotic systems 共生系统中由风吸积引起的多次新星喷发的模拟

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-12 DOI: 10.1093/mnras/staa3600

Y. Hillman, A. Kashi

{"title":"Simulations of multiple nova eruptions induced by wind accretion in symbiotic systems","authors":"Y. Hillman, A. Kashi","doi":"10.1093/mnras/staa3600","DOIUrl":"https://doi.org/10.1093/mnras/staa3600","url":null,"abstract":"We use a combined binary evolution code including dynamical effects to study nova eruptions in a symbiotic system. Following the evolution, over $sim10^5$ years, of multiple consecutive nova eruptions on the surface of a $1.25 M_odot$ white dwarf (WD) accretor, we present a comparison between simulations of two types of systems. The first is the common, well known, cataclysmic variable (CV) system in which a main sequence donor star transfers mass to its WD companion via Roche-lobe overflow. The second is a detached, widely separated, symbiotic system in which an asymptotic giant branch donor star transfers mass to its WD companion via strong winds. For the latter we use the Bondi-Hoyle-Lyttleton prescription along with orbital dynamics to calculate the accretion rate. We use the combined stellar evolution code to follow the nova eruptions of both simulations including changes in mass, accretion rate and orbital features. We find that while the average accretion rate for the CV remains fairly constant, the symbiotic system experiences distinct epochs of high and low accretion rates. The examination of epochs for which the accretion rates of both simulations are similar, shows that the evolutionary behaviors are identical. We obtain that for a given WD mass, the rate that mass is accreted ultimately determines the development, and that the stellar class of the donor is of no significance to the development of novae. We discuss several observed systems and find that our results are consistent with estimated parameters of novae in widely separated symbiotic systems.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79509170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Verification by binary systems 基于高分辨率近红外光谱的M矮星元素丰度:双星系统的验证

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-08 DOI: 10.1093/pasj/psaa101

H. Ishikawa, W. Aoki, T. Kotani, M. Kuzuhara, M. Omiya, A. Reiners, M. Zechmeister

{"title":"Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Verification by binary systems","authors":"H. Ishikawa, W. Aoki, T. Kotani, M. Kuzuhara, M. Omiya, A. Reiners, M. Zechmeister","doi":"10.1093/pasj/psaa101","DOIUrl":"https://doi.org/10.1093/pasj/psaa101","url":null,"abstract":"M dwarfs are prominent targets of planet search projects, and their chemical composition is crucial to understanding the formation process or interior of orbiting exoplanets. However, measurements of elemental abundances of M dwarfs have been limited due to difficulties in the analysis of their optical spectra. We conducted a detailed chemical analysis of five M dwarfs (T_eff ~3200--3800 K), which form binary systems with G/K-type stars, by performing a line-by-line analysis based on high-resolution (R ~80,000) near-infrared (960--1710 nm) spectra obtained with CARMENES. We determined the chemical abundances of eight elements (Na, Mg, K, Ca, Ti, Cr, Mn, and Fe), which are in agreement with those of the primary stars within measurement errors (~0.2 dex). Through the analysis process, we investigated the unique behavior of atomic lines in a cool atmosphere. Most atomic lines are sensitive to changes in abundance not only of the corresponding elements but also of other elements, especially dominant electron donors such as Na and Ca. The Ti I lines show a negative correlation with the overall metallicity at T_eff < 3400 K due to the consumption of neutral titanium by the formation of TiO molecules. These findings indicate that to correctly estimate the overall metallicity or the abundance of any element, we need to determine the abundances of other individual elements consistently.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87656419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Modified virial theorem for highly magnetized white dwarfs 高磁化白矮星的修正维里定理

arXiv: Solar and Stellar Astrophysics Pub Date : 2020-10-08 DOI: 10.1093/mnras/staa3136

B. Mukhopadhyay, A. Sarkar, C. Tout

{"title":"Modified virial theorem for highly magnetized white dwarfs","authors":"B. Mukhopadhyay, A. Sarkar, C. Tout","doi":"10.1093/mnras/staa3136","DOIUrl":"https://doi.org/10.1093/mnras/staa3136","url":null,"abstract":"Generally the virial theorem provides a relation between various components of energy integrated over a system. This helps us to understand the underlying equilibrium. Based on the virial theorem we can estimate, for example, the maximum allowed magnetic field in a star. Recent studies have proposed the existence of highly magnetized white dwarfs, with masses significantly higher than the Chandrasekhar limit. Surface magnetic fields of such white dwarfs could be more than 10^9 G with the central magnitude several orders higher. These white dwarfs could be significantly smaller in size than their ordinary counterparts (with surface fields restricted to about 10^9 G). In this paper we reformulate the virial theorem for non-rotating, highly magnetized white dwarfs (B-WDs) in which, unlike in previous formulations, the contribution of the magnetic pressure to the magnetohydrostatic balance cannot be neglected. Along with the new equation of magnetohydrostatic equilibrium, we approach the problem by invoking magnetic flux conservation and by varying the internal magnetic field with the matter density as a power law. Either of these choices are supported by previous independent work and neither violates any important physics. They are useful while there is no prior knowledge of field profile within a white dwarf. We then compute the modified gravitational, thermal and magnetic energies and examine how the magnetic pressure influences the properties of such white dwarfs. Based on our results we predict important properties of these B-WDs, which turn out to be independent of our chosen field profiles.","PeriodicalId":8493,"journal":{"name":"arXiv: Solar and Stellar Astrophysics","volume":"104 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87590953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4