Nils Candebat, Giuseppe Germano Sacco, Laura Magrini, Francesco Belfiore, Mathieu Van-der-Swaelmen, Stefano Zibetti
Context: New spectroscopic surveys will increase the number of astronomical objects requiring characterization by over tenfold.. Machine learning tools are required to address this data deluge in a fast and accurate fashion. Most machine learning algorithms can not estimate error directly, making them unsuitable for reliable science. Aims: We aim to train a supervised deep-learning algorithm tailored for high-resolution observational stellar spectra. This algorithm accurately infer precise estimates while providing coherent estimates of uncertainties by leveraging information from both the neural network and the spectra. Methods: We train a conditional Invertible Neural Network (cINN) on observational spectroscopic data obtained from the GIRAFFE spectrograph (HR10 and HR21 setups) within the Gaia-ESO survey. A key features of cINN is its ability to produce the Bayesian posterior distribution of parameters for each spectrum. By analyzing this distribution, we inferred parameters and their uncertainties. Several tests have been applied to study how parameters and errors are estimated. Results: We achieved an accuracy of 28K in $T_{text{eff}}$, 0.06 dex in $log g$, 0.03 dex in $[text{Fe/H}]$, and between 0.05 dex and 0.17 dex for the other abundances for high quality spectra. Accuracy remains stable with low signal-to-noise ratio spectra. The uncertainties obtained are well within the same order of magnitude. The network accurately reproduces astrophysical relationships both on the scale of the Milky Way and within smaller star clusters. We created a table containing the new parameters generated by our cINN. Conclusion: This neural network represents a compelling proposition for future astronomical surveys. These coherent derived uncertainties make it possible to reuse these estimates in other works as Bayesian priors and thus present a solid basis for future work.
{"title":"Inferring stellar parameters and their uncertainties from high-resolution spectroscopy using invertible neural networks","authors":"Nils Candebat, Giuseppe Germano Sacco, Laura Magrini, Francesco Belfiore, Mathieu Van-der-Swaelmen, Stefano Zibetti","doi":"arxiv-2409.10621","DOIUrl":"https://doi.org/arxiv-2409.10621","url":null,"abstract":"Context: New spectroscopic surveys will increase the number of astronomical\u0000objects requiring characterization by over tenfold.. Machine learning tools are\u0000required to address this data deluge in a fast and accurate fashion. Most\u0000machine learning algorithms can not estimate error directly, making them\u0000unsuitable for reliable science. Aims: We aim to train a supervised deep-learning algorithm tailored for\u0000high-resolution observational stellar spectra. This algorithm accurately infer\u0000precise estimates while providing coherent estimates of uncertainties by\u0000leveraging information from both the neural network and the spectra. Methods: We train a conditional Invertible Neural Network (cINN) on\u0000observational spectroscopic data obtained from the GIRAFFE spectrograph (HR10\u0000and HR21 setups) within the Gaia-ESO survey. A key features of cINN is its\u0000ability to produce the Bayesian posterior distribution of parameters for each\u0000spectrum. By analyzing this distribution, we inferred parameters and their\u0000uncertainties. Several tests have been applied to study how parameters and\u0000errors are estimated. Results: We achieved an accuracy of 28K in $T_{text{eff}}$, 0.06 dex in\u0000$log g$, 0.03 dex in $[text{Fe/H}]$, and between 0.05 dex and 0.17 dex for\u0000the other abundances for high quality spectra. Accuracy remains stable with low\u0000signal-to-noise ratio spectra. The uncertainties obtained are well within the\u0000same order of magnitude. The network accurately reproduces astrophysical\u0000relationships both on the scale of the Milky Way and within smaller star\u0000clusters. We created a table containing the new parameters generated by our\u0000cINN. Conclusion: This neural network represents a compelling proposition for\u0000future astronomical surveys. These coherent derived uncertainties make it\u0000possible to reuse these estimates in other works as Bayesian priors and thus\u0000present a solid basis for future work.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257982","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}
The Serkowski relation is the cornerstone of studies of starlight polarization as a function of wavelength. Although empirical, its extensive use since its inception to describe polarization induced by interstellar dust has elevated the relation to the status of an indisputable "law", serving as the benchmark for validating interstellar dust grain models. We revisit the effects of the 3D structure of the interstellar medium (ISM) on the wavelength dependence of interstellar polarization. We use analytical models to show how the wavelength dependence of both the polarization fraction and direction is affected by the presence of multiple clouds along the line of sight (LOS), accounting for recent developments in dust distribution modelling and utilizing an expanded archive of stellar polarization measurements. We highlight concrete examples of stars whose polarization profiles are severely affected by LOS variations of the dust grain and magnetic field properties, and we provide a recipe to accurately fit multiple cloud Serkowski models to such cases. We present, for the first time, compelling observational evidence that the 3D structure of the magnetized ISM often results to the violation of the Serkowski relation. We show that 3D effects impact interstellar cloud parameters derived from Serkowski fits. In particular, the dust size distribution in single - cloud sightlines may differ from analyses that ignore 3D effects, with important implications for dust modelling in the Galaxy. Our results suggest that multiband stellar polarization measurements offer an independent probe of the LOS variations of the magnetic field, constituting a valuable new tool for the 3D cartography of the ISM. We caution that, unless 3D effects are explicitly accounted for, a poor fit to the Serkowski relation does not, by itself, constitute conclusive evidence that a star is intrinsically polarized.
谢尔科夫斯基关系是研究星光极化与波长函数关系的基石。尽管它是经验性的，但自诞生以来，它被广泛用于描述星际尘埃引起的偏振，这使得该关系上升为无可争议的 "定律"，成为验证星际尘埃粒子模型的基准。我们重新审视了星际介质（ISM）的三维结构对星际偏振波长依赖性的影响。我们使用分析模型来说明偏振分数和方向的波长依赖性如何受到沿视线（LOS）存在的多个云团的影响，同时考虑到尘粒分布模型的最新发展，并利用扩充的恒星偏振测量档案。我们强调了一些恒星的具体例子，这些恒星的偏振剖面受到视线中尘粒和磁场特性变化的严重影响，我们还提供了精确拟合多云 Serkowski 模型的方法。我们首次提出了令人信服的观测证据，表明磁化 ISM 的三维结构经常导致违反塞尔科夫斯基相关性。我们表明，三维效应会影响由塞尔科夫斯基拟合得出的星际云参数。特别是，单个云视线中的尘埃大小分布可能与忽略三维效应的分析不同，这对银河系的尘埃建模具有重要影响。我们的研究结果表明，多波段恒星偏振测量可以独立探测 LOS 磁场的变化，是绘制 ISM 三维地图的宝贵新工具。我们要提醒的是，除非三维效应被明确考虑在内，否则与塞尔科夫斯基关系的拟合效果不佳本身并不能构成恒星本质上偏振的确凿证据。
{"title":"3D ISM structure challenges the Serkowski relation","authors":"Nikolaos Mandarakas, Konstantinos Tassis, Raphael Skalidis","doi":"arxiv-2409.10317","DOIUrl":"https://doi.org/arxiv-2409.10317","url":null,"abstract":"The Serkowski relation is the cornerstone of studies of starlight\u0000polarization as a function of wavelength. Although empirical, its extensive use\u0000since its inception to describe polarization induced by interstellar dust has\u0000elevated the relation to the status of an indisputable \"law\", serving as the\u0000benchmark for validating interstellar dust grain models. We revisit the effects\u0000of the 3D structure of the interstellar medium (ISM) on the wavelength\u0000dependence of interstellar polarization. We use analytical models to show how\u0000the wavelength dependence of both the polarization fraction and direction is\u0000affected by the presence of multiple clouds along the line of sight (LOS),\u0000accounting for recent developments in dust distribution modelling and utilizing\u0000an expanded archive of stellar polarization measurements. We highlight concrete\u0000examples of stars whose polarization profiles are severely affected by LOS\u0000variations of the dust grain and magnetic field properties, and we provide a\u0000recipe to accurately fit multiple cloud Serkowski models to such cases. We\u0000present, for the first time, compelling observational evidence that the 3D\u0000structure of the magnetized ISM often results to the violation of the Serkowski\u0000relation. We show that 3D effects impact interstellar cloud parameters derived\u0000from Serkowski fits. In particular, the dust size distribution in single -\u0000cloud sightlines may differ from analyses that ignore 3D effects, with\u0000important implications for dust modelling in the Galaxy. Our results suggest\u0000that multiband stellar polarization measurements offer an independent probe of\u0000the LOS variations of the magnetic field, constituting a valuable new tool for\u0000the 3D cartography of the ISM. We caution that, unless 3D effects are\u0000explicitly accounted for, a poor fit to the Serkowski relation does not, by\u0000itself, constitute conclusive evidence that a star is intrinsically polarized.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258046","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}
We present a study of the detached eclipsing binary TV~Mon using spectra from the LAMOST medium-resolution survey and ASAS-SN, CoRoT photometry. We applied multiple-epochs spectral fitting to derive RV and spectral parameters. The analysis of eclipses in CoRoT data told us relative sizes of the stellar components and almost edge-on circular orbit. Combining spectral and photometrical solution we estimated masses and radii of the components: $M_{A,B}=2.063pm0.033,~0.218pm0.004~M_odot$, $R_{A,B}=2.427pm0.014,~2.901pm0.016~R_odot$. SED analysis and Gaia parallax allowed us to get estimation of temperatures $T_{A,B}=7624^{+194}_{-174},~5184^{+130}_{-123}$ K and distance $d=907pm11$ pc. We identified three $delta$ Scuti type pulsation frequencies in primary component, while we also suspect TV~Mon having a long period variability with period $P_{rm long}sim128$ days and spot activity in secondary component. This system experienced intensive mass transfer and mass ratio reversal in the past, currently showing no signs of mass transfer in the spectra. The low mass component will lose its outer envelope and shrink to the helium white dwarf, which mass and orbital period are in good agreement with evolutionary models predictions.
{"title":"TV Mon - post mass transfer Algol type binary with $δ$ Scuti pulsations in primary component","authors":"Mikhail Kovalev, Zhenwei Li, Jianping Xiong, Azizbek Matekov, Zhang Bo, Xuefei Chen, Zhanwen Han","doi":"arxiv-2409.09902","DOIUrl":"https://doi.org/arxiv-2409.09902","url":null,"abstract":"We present a study of the detached eclipsing binary TV~Mon using spectra from\u0000the LAMOST medium-resolution survey and ASAS-SN, CoRoT photometry. We applied\u0000multiple-epochs spectral fitting to derive RV and spectral parameters. The\u0000analysis of eclipses in CoRoT data told us relative sizes of the stellar\u0000components and almost edge-on circular orbit. Combining spectral and\u0000photometrical solution we estimated masses and radii of the components:\u0000$M_{A,B}=2.063pm0.033,~0.218pm0.004~M_odot$,\u0000$R_{A,B}=2.427pm0.014,~2.901pm0.016~R_odot$. SED analysis and Gaia parallax\u0000allowed us to get estimation of temperatures\u0000$T_{A,B}=7624^{+194}_{-174},~5184^{+130}_{-123}$ K and distance $d=907pm11$\u0000pc. We identified three $delta$ Scuti type pulsation frequencies in primary\u0000component, while we also suspect TV~Mon having a long period variability with\u0000period $P_{rm long}sim128$ days and spot activity in secondary component.\u0000This system experienced intensive mass transfer and mass ratio reversal in the\u0000past, currently showing no signs of mass transfer in the spectra. The low mass\u0000component will lose its outer envelope and shrink to the helium white dwarf,\u0000which mass and orbital period are in good agreement with evolutionary models\u0000predictions.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257986","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}
S. C. Susarla, A. Chalumeau, C. Tiburzi, E. F. Keane, J. P. W. Verbiest, J. S. Hazboun, M. A. Krishnakumar, F. Iraci, G. M. Shaifullah, A. Golden, A. S. Bak Nielsen, J. Donner, J. M. Grießmeier, M. J. Keith, S. Osłowski, N. K. Porayko, M. Serylak, J. M. Anderson, M. Brüggen, B. Ciardi, R. J. Dettmar, M. Hoeft, J. Künsemöller, D. Schwarz, C. Vocks
High-precision pulsar timing is highly dependent on precise and accurate modeling of any effects that impact the data. It was shown that commonly used Solar Wind models do not accurately account for variability in the amplitude of the Solar wind on both short and long time scales. In this study, we test and validate a new, cutting-edge Solar wind modeling method included in the texttt{enterprise} software suite through extended simulations, and we apply it to investigate temporal variability in LOFAR data. Our model testing scheme in itself provides an invaluable asset for pulsar timing array (PTA) experiments. As improperly accounting for the solar wind signature in pulsar data can induce false-positive signals, it is of fundamental importance to include in any such investigations. We employ a Bayesian approach utilizing a continuously varying Gaussian process to model the solar wind referred to as Solar Wind Gaussian Process (SWGP). We conduct noise analysis on eight pulsars from the LOFAR dataset with most pulsars having a timespan of $sim 11$ years encompassing one full solar activity cycle. Our analysis reveals a strong correlation between the electron density at 1 AU and the ecliptic latitude (ELAT) of the pulsar. Pulsars with $|ELAT|< 3^{circ}$ exhibit significantly higher average electron densities. We observe distinct temporal patterns in electron densities in different pulsars. In particular, pulsars within $|ELAT|< 3^{circ}$ exhibit similar temporal variations, while the electron densities of those outside this range correlate with the solar activity cycle. The continuous variability in electron density offered in this model represents a substantial improvement over previous models, which assume a single value for piece-wise bins of time. This advancement holds promise for solar wind modeling in future International Pulsar Timing Array data combinations.
{"title":"Exploring the time variability of the Solar Wind using LOFAR pulsar data","authors":"S. C. Susarla, A. Chalumeau, C. Tiburzi, E. F. Keane, J. P. W. Verbiest, J. S. Hazboun, M. A. Krishnakumar, F. Iraci, G. M. Shaifullah, A. Golden, A. S. Bak Nielsen, J. Donner, J. M. Grießmeier, M. J. Keith, S. Osłowski, N. K. Porayko, M. Serylak, J. M. Anderson, M. Brüggen, B. Ciardi, R. J. Dettmar, M. Hoeft, J. Künsemöller, D. Schwarz, C. Vocks","doi":"arxiv-2409.09838","DOIUrl":"https://doi.org/arxiv-2409.09838","url":null,"abstract":"High-precision pulsar timing is highly dependent on precise and accurate\u0000modeling of any effects that impact the data. It was shown that commonly used\u0000Solar Wind models do not accurately account for variability in the amplitude of\u0000the Solar wind on both short and long time scales. In this study, we test and\u0000validate a new, cutting-edge Solar wind modeling method included in the\u0000texttt{enterprise} software suite through extended simulations, and we apply\u0000it to investigate temporal variability in LOFAR data. Our model testing scheme\u0000in itself provides an invaluable asset for pulsar timing array (PTA)\u0000experiments. As improperly accounting for the solar wind signature in pulsar\u0000data can induce false-positive signals, it is of fundamental importance to\u0000include in any such investigations. We employ a Bayesian approach utilizing a\u0000continuously varying Gaussian process to model the solar wind referred to as\u0000Solar Wind Gaussian Process (SWGP). We conduct noise analysis on eight pulsars\u0000from the LOFAR dataset with most pulsars having a timespan of $sim 11$ years\u0000encompassing one full solar activity cycle. Our analysis reveals a strong\u0000correlation between the electron density at 1 AU and the ecliptic latitude\u0000(ELAT) of the pulsar. Pulsars with $|ELAT|< 3^{circ}$ exhibit significantly\u0000higher average electron densities. We observe distinct temporal patterns in\u0000electron densities in different pulsars. In particular, pulsars within $|ELAT|<\u00003^{circ}$ exhibit similar temporal variations, while the electron densities of\u0000those outside this range correlate with the solar activity cycle. The\u0000continuous variability in electron density offered in this model represents a\u0000substantial improvement over previous models, which assume a single value for\u0000piece-wise bins of time. This advancement holds promise for solar wind modeling\u0000in future International Pulsar Timing Array data combinations.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257987","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}
Three sets of complete multi-color light curves of V694 Peg observed in 2013, 2015 and 2019 were presented and analyzed. Our photometric solutions show that this system is an A-type shallow contact binary in 2013 and 2015, while it converted to a W-type one in 2019. A large cool spot on the component of this binary could explain the conversion, implying the W-type phenomena may be caused by magnetic activity of the components. We have collected available data of this binary and calculated 505 times of light minimum, which span 17 years. The orbital period investigation based on these timings shows there is a long-term period increase at a rate of $dP/dt$ = 4.3($pm$ 0.3)$times$ 10$^{-9}$ d yr$^{-1}$ superposed on a periodic variation with a period of 11.81($pm$ 0.06) years. The cyclic orbital variation may be the result of magnetic activity cycles or the existence of a third body. Till now, only 8 transformed systems including V694 Peg have been reported. Compared with other converting contact systems between A-type and W-type, V694 Peg is recorded as the shortest-period one. All of these converting systems are late-type (later than F7) contact binaries with O'Connell effect and show cyclic period variation, which indicates that magnetic activity may be the reason for the conversion between the two types of contact binaries. For investigating the nature of A-type and W-type phenomena, the discovery of more converting contact binaries is essential.
{"title":"A possible explanation of W-type phenomena in V694 Peg","authors":"Hu-Shan Xu, Li-Ying Zhu","doi":"arxiv-2409.09705","DOIUrl":"https://doi.org/arxiv-2409.09705","url":null,"abstract":"Three sets of complete multi-color light curves of V694 Peg observed in 2013,\u00002015 and 2019 were presented and analyzed. Our photometric solutions show that\u0000this system is an A-type shallow contact binary in 2013 and 2015, while it\u0000converted to a W-type one in 2019. A large cool spot on the component of this\u0000binary could explain the conversion, implying the W-type phenomena may be\u0000caused by magnetic activity of the components. We have collected available data\u0000of this binary and calculated 505 times of light minimum, which span 17 years.\u0000The orbital period investigation based on these timings shows there is a\u0000long-term period increase at a rate of $dP/dt$ = 4.3($pm$ 0.3)$times$\u000010$^{-9}$ d yr$^{-1}$ superposed on a periodic variation with a period of\u000011.81($pm$ 0.06) years. The cyclic orbital variation may be the result of\u0000magnetic activity cycles or the existence of a third body. Till now, only 8\u0000transformed systems including V694 Peg have been reported. Compared with other\u0000converting contact systems between A-type and W-type, V694 Peg is recorded as\u0000the shortest-period one. All of these converting systems are late-type (later\u0000than F7) contact binaries with O'Connell effect and show cyclic period\u0000variation, which indicates that magnetic activity may be the reason for the\u0000conversion between the two types of contact binaries. For investigating the\u0000nature of A-type and W-type phenomena, the discovery of more converting contact\u0000binaries is essential.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"206 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258048","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}
A common envelope (CE) is proposed as the origin of the early postoutburst spectra of many novae. A simple model is proposed to explain the properties of the CE based on the emission line strengths and an assumed density distribution. Rapid changes in the spectrum during postoutburst decline are suggested as possible evidence for a CE. Time-resolved spectra from the ARAS group show sudden spectral shifts that are correlated with detected gamma ray emission, suggestive of its possible origin on the WD that produces a change in condition within the CE. Episodic mass loss, formation of thea transient heavy element absorption systems, and dissipation of the CE may be triggered by gamma ray emission.
{"title":"Common Envelopes, Gamma Rays, and Sudden Spectral Changes of Novae","authors":"Robert Williams, Russell Ryan, Richard Rudy","doi":"arxiv-2409.09565","DOIUrl":"https://doi.org/arxiv-2409.09565","url":null,"abstract":"A common envelope (CE) is proposed as the origin of the early postoutburst\u0000spectra of many novae. A simple model is proposed to explain the properties of\u0000the CE based on the emission line strengths and an assumed density\u0000distribution. Rapid changes in the spectrum during postoutburst decline are\u0000suggested as possible evidence for a CE. Time-resolved spectra from the ARAS\u0000group show sudden spectral shifts that are correlated with detected gamma ray\u0000emission, suggestive of its possible origin on the WD that produces a change in\u0000condition within the CE. Episodic mass loss, formation of thea transient heavy\u0000element absorption systems, and dissipation of the CE may be triggered by gamma\u0000ray emission.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258040","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}
Jing Wen, Ming Yang, Jian Gao, Bingqiu Chen, Yi Ren, Biwei Jiang
Asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) exhibit significant mass loss phenomena and are considered important sources of interstellar dust. In this work, we employed an uniform method of spectral energy distribution fitting to analyze a large, and hence statistically significant, sample of approximately 40,000 RSGs and AGBs in the Magellanic Clouds (MCs), providing a new catalog of evolved stars that includes stellar parameters and dust properties. Our results reveal that the total dust-production rate (DPR) of the Large Magellanic Cloud is approximately $9.69times10^{-6},rm{M_{odot }, yr^{-1}}$, while it is around $1.75times10^{-6},rm{M_{odot },yr^{-1}}$ for the Small Magellanic Cloud, with a few stars significantly contributing to the total DPR. No significant differences were observed in the contributions to DPR from carbon-rich and oxygen-rich (O-rich) evolved stars in the MCs. We explored the relations between stellar parameters (luminosity, infrared color, period, amplitude) and mass-loss rate (MLR) for evolved stars. A prominent turning point at $log{(L/L_{odot})} approx 4.4$ appears in the luminosity-MLR diagram of RSGs, potentially related to the mass-loss mechanism of RSGs. The luminosity-MLR relation of AGBs is highly scattered. The DPR of AGBs shows a clear change with pulsation period and amplitude, with DPR exhibiting a drastic increase at pulsation periods of approximately 300 days and I-band amplitudes greater than 0.5 mag. Metallicity has some impact on the DPR of O-rich stars, with lower metallicity seeming to result in lower mean DPR and a higher proportion of optically thin stars.
{"title":"Mass-loss Rate of Highly Evolved Stars in the Magellanic Clouds","authors":"Jing Wen, Ming Yang, Jian Gao, Bingqiu Chen, Yi Ren, Biwei Jiang","doi":"arxiv-2409.09751","DOIUrl":"https://doi.org/arxiv-2409.09751","url":null,"abstract":"Asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) exhibit\u0000significant mass loss phenomena and are considered important sources of\u0000interstellar dust. In this work, we employed an uniform method of spectral\u0000energy distribution fitting to analyze a large, and hence statistically\u0000significant, sample of approximately 40,000 RSGs and AGBs in the Magellanic\u0000Clouds (MCs), providing a new catalog of evolved stars that includes stellar\u0000parameters and dust properties. Our results reveal that the total\u0000dust-production rate (DPR) of the Large Magellanic Cloud is approximately\u0000$9.69times10^{-6},rm{M_{odot }, yr^{-1}}$, while it is around\u0000$1.75times10^{-6},rm{M_{odot },yr^{-1}}$ for the Small Magellanic Cloud,\u0000with a few stars significantly contributing to the total DPR. No significant\u0000differences were observed in the contributions to DPR from carbon-rich and\u0000oxygen-rich (O-rich) evolved stars in the MCs. We explored the relations\u0000between stellar parameters (luminosity, infrared color, period, amplitude) and\u0000mass-loss rate (MLR) for evolved stars. A prominent turning point at\u0000$log{(L/L_{odot})} approx 4.4$ appears in the luminosity-MLR diagram of\u0000RSGs, potentially related to the mass-loss mechanism of RSGs. The\u0000luminosity-MLR relation of AGBs is highly scattered. The DPR of AGBs shows a\u0000clear change with pulsation period and amplitude, with DPR exhibiting a drastic\u0000increase at pulsation periods of approximately 300 days and I-band amplitudes\u0000greater than 0.5 mag. Metallicity has some impact on the DPR of O-rich stars,\u0000with lower metallicity seeming to result in lower mean DPR and a higher\u0000proportion of optically thin stars.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257988","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}
Li-Heng Wang, Kai Li, Ya-Ni Guo, Jing-Yi Wang, Xiang Gao, Xing Gao, Guo-You Sun
This paper selected eight totally eclipsing contact binaries for photometric and spectroscopic studies, spectral data were analyzed by ULySS, and photometric data were analyzed using PHOEBE through MCMC sampling. We used two methods to calculate the initial values for running MCMC: one method is a new approach proposed by ourselves to model light curves without spots, while the other method is the genetic algorithm (GA) which can determine physical parameters with spot. Due to the results, these eight targets are all small mass ratio contact binary stars with a mass ratio below 0.25. There are four systems exhibiting O'Connell effect. By adding a dark spot on the primary component, the ideal fitting can be obtained. Meanwhile, it was found that two systems are shallow contact binaries, while the remaining six are moderate contact binaries. An O-C analysis of the eight eclipsing binary stars revealed that seven of them exhibit long-term changes. Four of them display a long-term decreasing trend, while the other three show a long-term increasing trend, and two targets exhibit periodic variations. The decrease in period may be caused by the transfer of matter from the more massive component to the less massive component, while the increase in period may be caused by the transfer of matter from the less massive component to the more massive component. The absolute physical parameters, orbital angular momentum, initial masses, and ages of these eight systems were calculated. Additionally, their mass-luminosity and mass-radius distributions were analyzed.
{"title":"Photometric and Spectroscopic analysis of eight totally eclipsing contact binaries with small mass ratios","authors":"Li-Heng Wang, Kai Li, Ya-Ni Guo, Jing-Yi Wang, Xiang Gao, Xing Gao, Guo-You Sun","doi":"arxiv-2409.09743","DOIUrl":"https://doi.org/arxiv-2409.09743","url":null,"abstract":"This paper selected eight totally eclipsing contact binaries for photometric\u0000and spectroscopic studies, spectral data were analyzed by ULySS, and\u0000photometric data were analyzed using PHOEBE through MCMC sampling. We used two\u0000methods to calculate the initial values for running MCMC: one method is a new\u0000approach proposed by ourselves to model light curves without spots, while the\u0000other method is the genetic algorithm (GA) which can determine physical\u0000parameters with spot. Due to the results, these eight targets are all small\u0000mass ratio contact binary stars with a mass ratio below 0.25. There are four\u0000systems exhibiting O'Connell effect. By adding a dark spot on the primary\u0000component, the ideal fitting can be obtained. Meanwhile, it was found that two\u0000systems are shallow contact binaries, while the remaining six are moderate\u0000contact binaries. An O-C analysis of the eight eclipsing binary stars revealed\u0000that seven of them exhibit long-term changes. Four of them display a long-term\u0000decreasing trend, while the other three show a long-term increasing trend, and\u0000two targets exhibit periodic variations. The decrease in period may be caused\u0000by the transfer of matter from the more massive component to the less massive\u0000component, while the increase in period may be caused by the transfer of matter\u0000from the less massive component to the more massive component. The absolute\u0000physical parameters, orbital angular momentum, initial masses, and ages of\u0000these eight systems were calculated. Additionally, their mass-luminosity and\u0000mass-radius distributions were analyzed.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258038","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}
In this study, we explore the elongated granulations and stretched dark lanes within the emerging anti-Hale active region NOAA 12720. Utilizing high-resolution observations from the New Vacuum Solar Telescope, we discern a prevalence of elongated granules and stretched dark lanes associated with the emergence of new magnetic flux positioned between two primary opposing magnetic polarities. These elongated granulations and stretched dark lanes exhibit an alignment of strong transverse fields and a significant inclination angle. The endpoints of these features separate from each other, with their midpoints predominantly characterized by blue-shifted signals in the photosphere. This suggests a close association between elongated granules and stretched dark lanes with the newly emerging flux. Additionally, we find that the stretched dark lanes display a more pronounced correlation with strong blue shifts and photospheric transverse magnetic fields compared to the elongated granulations. The transverse magnetic field within these stretched dark lanes reaches magnitudes of approximately 300 to 400 G, and the inclination angle demonstrates an "arch-like" pattern along the trajectory of the stretched dark lane. Based on these observed characteristics, we infer the presence of an emerging flux tube with an "arch-like" shape situated along the stretched dark lane. Consequently, we conclude that the stretched dark lanes likely represent manifestations of the emerging flux tube, while the elongated granulations may correspond to the gaps between the emerging flux tubes.
{"title":"The nature of elongated granulations and stretched dark lanes in a newly emerging flux region","authors":"Jincheng Wang, Xiaoli Yan","doi":"arxiv-2409.09688","DOIUrl":"https://doi.org/arxiv-2409.09688","url":null,"abstract":"In this study, we explore the elongated granulations and stretched dark lanes\u0000within the emerging anti-Hale active region NOAA 12720. Utilizing\u0000high-resolution observations from the New Vacuum Solar Telescope, we discern a\u0000prevalence of elongated granules and stretched dark lanes associated with the\u0000emergence of new magnetic flux positioned between two primary opposing magnetic\u0000polarities. These elongated granulations and stretched dark lanes exhibit an\u0000alignment of strong transverse fields and a significant inclination angle. The\u0000endpoints of these features separate from each other, with their midpoints\u0000predominantly characterized by blue-shifted signals in the photosphere. This\u0000suggests a close association between elongated granules and stretched dark\u0000lanes with the newly emerging flux. Additionally, we find that the stretched\u0000dark lanes display a more pronounced correlation with strong blue shifts and\u0000photospheric transverse magnetic fields compared to the elongated granulations.\u0000The transverse magnetic field within these stretched dark lanes reaches\u0000magnitudes of approximately 300 to 400 G, and the inclination angle\u0000demonstrates an \"arch-like\" pattern along the trajectory of the stretched dark\u0000lane. Based on these observed characteristics, we infer the presence of an\u0000emerging flux tube with an \"arch-like\" shape situated along the stretched dark\u0000lane. Consequently, we conclude that the stretched dark lanes likely represent\u0000manifestations of the emerging flux tube, while the elongated granulations may\u0000correspond to the gaps between the emerging flux tubes.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258041","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}
Masafumi Niwano, Michael M. Fausnaugh, Ryan M. Lau, Kishalay De, Roberto Soria, George R. Ricker, Roland Vanderspek, Michael C. B. Ashley, Nicholas Earley, Matthew J. Hankins, Mansi M. Kasliwal, Anna M. Moore, Jamie Soon, Tony Travouillon, Mahito Sasada, Ichiro Takahashi, Yoichi Yatsu, Nobuyuki Kawai
The mechanism of X-ray outbursts in Be X-ray binaries remains a mystery, and understanding their circumstellar disks is crucial for a solution of the mass-transfer problem. In particular, it is important to identify the Be star activities (e.g., pulsations) that cause mass ejection and, hence, disk formation. Therefore, we investigated the relationship between optical flux oscillations and the infrared (IR) excess in a sample of five Be X-ray binaries. Applying the Lomb-Scargle technique to high-cadence optical light curves from the Transiting Exoplanet Survey Satellite (TESS), we detected several significant oscillation modes in the 3 to 24 hour period range for each source. We also measured the IR excess (a proxy for disk growth) of those five sources, using J-band light curves from Palomar Gattini-IR. In four of the five sources, we found anti-correlations between the IR excess and the amplitude of the main flux oscillation modes. This result is inconsistent with the conventional idea that non-radial pulsations drive mass ejections. We propose an alternative scenario where internal temperature variations in the Be star cause transitions between pulsation-active and mass-ejection-active states.
Be X 射线双星的 X 射线爆发机制仍然是一个谜，了解它们的周星盘对于解决它们的质量转移问题至关重要。尤其重要的是，要找出导致质量喷射并进而导致盘变形的Be星活动（如脉冲）。因此，我们研究了五个 Be X 射线双星样本中光学通量振荡与红外（IR）过量之间的关系。我们对来自 Transiting Exoplanet Survey Satellite（TESS）的高信度光学光曲线应用了 Lomb-Scargle 技术，在每个光源的 3 到 24 小时周期范围内检测到了几种显著的振荡模式。我们还利用 Palomar Gattini-IR 的 J 波段光变曲线测量了这五个星源的红外过量（圆盘生长的代用指标）。在这五个来源中的四个来源中，我们发现红外过量与主通量振荡模式的振幅之间存在反相关关系。这一结果与非径向脉动驱动质量抛射的传统观点不一致。我们提出了另一种设想：Be 星的内部温度变化会导致脉动活跃态和质量喷射活跃态之间的转换。
{"title":"Possible anti-correlations between pulsation amplitudes and the disk growth of Be stars in giant-outbursting Be X-ray binaries","authors":"Masafumi Niwano, Michael M. Fausnaugh, Ryan M. Lau, Kishalay De, Roberto Soria, George R. Ricker, Roland Vanderspek, Michael C. B. Ashley, Nicholas Earley, Matthew J. Hankins, Mansi M. Kasliwal, Anna M. Moore, Jamie Soon, Tony Travouillon, Mahito Sasada, Ichiro Takahashi, Yoichi Yatsu, Nobuyuki Kawai","doi":"arxiv-2409.09581","DOIUrl":"https://doi.org/arxiv-2409.09581","url":null,"abstract":"The mechanism of X-ray outbursts in Be X-ray binaries remains a mystery, and\u0000understanding their circumstellar disks is crucial for a solution of the\u0000mass-transfer problem. In particular, it is important to identify the Be star\u0000activities (e.g., pulsations) that cause mass ejection and, hence, disk\u0000formation. Therefore, we investigated the relationship between optical flux\u0000oscillations and the infrared (IR) excess in a sample of five Be X-ray\u0000binaries. Applying the Lomb-Scargle technique to high-cadence optical light\u0000curves from the Transiting Exoplanet Survey Satellite (TESS), we detected\u0000several significant oscillation modes in the 3 to 24 hour period range for each\u0000source. We also measured the IR excess (a proxy for disk growth) of those five\u0000sources, using J-band light curves from Palomar Gattini-IR. In four of the five\u0000sources, we found anti-correlations between the IR excess and the amplitude of\u0000the main flux oscillation modes. This result is inconsistent with the\u0000conventional idea that non-radial pulsations drive mass ejections. We propose\u0000an alternative scenario where internal temperature variations in the Be star\u0000cause transitions between pulsation-active and mass-ejection-active states.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258039","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}
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