S. Reyero Serantes, L. Oskinova, W. -R. Hamann, V. M. Gómez-González, H. Todt, D. Pauli, R. Soria, D. R. Gies, J. M. Torrejón, T. Bulik, V. Ramachandran, A. A. C. Sander, E. Bozzo, J. Poutanen
Ultra-luminous X-ray sources (ULXs) are high-mass X-ray binaries with an X-ray luminosity above $10^{39}$ erg s$^{-1}$. These ULXs can be powered by black holes that are more massive than $20M_odot$, accreting in a standard regime, or lighter compact objects accreting supercritically. There are only a few ULXs with known optical or UV counterparts, and their nature is debated. Determining whether optical/UV radiation is produced by the donor star or by the accretion disc is crucial for understanding ULX physics and testing massive binary evolution. We conduct, for the first time, a fully consistent multi-wavelength spectral analysis of a ULX and its circumstellar nebula. We aim to establish the donor star type and test the presence of strong disc winds in the prototypical ULX Holmberg II X-1 (Ho II X-1). We intent to obtain a realistic spectral energy distribution of the ionising source, which is needed for robust nebula analysis. We acquired new UV spectra of Ho II X-1 with the HST and complemented them with archival optical and X-ray data. We explored the spectral energy distribution of the source and analysed the spectra using the stellar atmosphere code PoWR and the photoionisation code Cloudy. Our analysis of the X-ray, UV, and optical spectra of Ho II X-1 and its nebula consistently explains the observations. We do not find traces of disc wind signatures in the UV and the optical, rejecting previous claims of the ULX being a supercritical accretor. The optical/UV counterpart of HoII X-1 is explained by a B-type supergiant donor star. Thus, the observations are fully compatible with Ho II X-1 being a close binary consisting of an $gtrsim 66,M_odot$ black hole accreting matter from an $simeq 22 M_odot$ B-supergiant companion. Also, we propose a possible evolution scenario for the system, suggesting that Ho II X-1 is a potential gravitational wave source progenitor.
超亮X射线源（ULX）是指X射线光度超过10^{39}$ erg s$^{-1}$的高质X射线双星。这些超光速X射线源可能是由质量超过20M_odot$的黑洞提供能量的，这些黑洞以标准方式吸积，或者是由超临界方式吸积的较轻的紧凑天体提供能量的。确定光学/紫外辐射是由供体恒星还是由吸积盘产生的，对于理解ULX物理学和测试大质量双星演化至关重要。我们首次对ULX及其周围星云进行了完全一致的多波长光谱分析。我们的目的是确定供体星的类型，并检验原型ULX Holmberg II X-1（Ho II X-1）中是否存在强圆盘风。我们打算获得电离源的实际光谱能量分布，这对于进行可靠的星云分析是必要的。我们用HST获取了Ho II X-1的新紫外光谱，并用存档的光学和X射线数据对其进行了补充。我们探索了该星源的光谱能量分布，并使用恒星大气层代码PoWR和光离子化代码Cloudy对光谱进行了分析。我们对Ho II X-1及其星云的X射线、紫外线和光学光谱的分析一致地解释了观测结果。我们在紫外和光学光谱中都没有发现盘风的痕迹，这就否定了以前关于超临界ULX是一个超临界加速器的说法。HoII X-1的光学/紫外对应星可以用一颗B型超巨供体星来解释。因此，观测结果完全符合Ho II X-1是一个近双星，由一个$gtrsim 66, M_odot$黑洞和一个$simeq 22 M_odot$B型超巨伴星的物质组成。同时，我们还提出了该系统可能的演化方案，表明Ho II X-1是一个潜在的引力波源原生体。
{"title":"Multi-wavelength spectroscopic analysis of the ULX Holmberg II","authors":"S. Reyero Serantes, L. Oskinova, W. -R. Hamann, V. M. Gómez-González, H. Todt, D. Pauli, R. Soria, D. R. Gies, J. M. Torrejón, T. Bulik, V. Ramachandran, A. A. C. Sander, E. Bozzo, J. Poutanen","doi":"arxiv-2409.12133","DOIUrl":"https://doi.org/arxiv-2409.12133","url":null,"abstract":"Ultra-luminous X-ray sources (ULXs) are high-mass X-ray binaries with an\u0000X-ray luminosity above $10^{39}$ erg s$^{-1}$. These ULXs can be powered by\u0000black holes that are more massive than $20M_odot$, accreting in a standard\u0000regime, or lighter compact objects accreting supercritically. There are only a\u0000few ULXs with known optical or UV counterparts, and their nature is debated.\u0000Determining whether optical/UV radiation is produced by the donor star or by\u0000the accretion disc is crucial for understanding ULX physics and testing massive\u0000binary evolution. We conduct, for the first time, a fully consistent\u0000multi-wavelength spectral analysis of a ULX and its circumstellar nebula. We\u0000aim to establish the donor star type and test the presence of strong disc winds\u0000in the prototypical ULX Holmberg II X-1 (Ho II X-1). We intent to obtain a\u0000realistic spectral energy distribution of the ionising source, which is needed\u0000for robust nebula analysis. We acquired new UV spectra of Ho II X-1 with the\u0000HST and complemented them with archival optical and X-ray data. We explored the\u0000spectral energy distribution of the source and analysed the spectra using the\u0000stellar atmosphere code PoWR and the photoionisation code Cloudy. Our analysis\u0000of the X-ray, UV, and optical spectra of Ho II X-1 and its nebula consistently\u0000explains the observations. We do not find traces of disc wind signatures in the\u0000UV and the optical, rejecting previous claims of the ULX being a supercritical\u0000accretor. The optical/UV counterpart of HoII X-1 is explained by a B-type\u0000supergiant donor star. Thus, the observations are fully compatible with Ho II\u0000X-1 being a close binary consisting of an $gtrsim 66,M_odot$ black hole\u0000accreting matter from an $simeq 22 M_odot$ B-supergiant companion. Also, we\u0000propose a possible evolution scenario for the system, suggesting that Ho II X-1\u0000is a potential gravitational wave source progenitor.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257934","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 characterize blue straggler stars (BSS) and yellow straggler stars (YSS) of an open cluster (OC) Berkeley 39 using multi-wavelength observations including Swift/UVOT. Our analysis also makes use of ultraviolet (UV) data from GALEX, optical data from Gaia DR3 and Pan-STARRS, and infrared data from 2MASS, Spitzer/IRAC, and WISE. Berkeley 39 is a ~6 Gyr old Galactic OC located at a distance of ~4200 pc. We identify 729 sources as cluster members utilizing a machine learning algorithm, ML-MOC, on Gaia DR3 data. Of these, 17 sources are classified as BSS candidates and four as YSS candidates. We construct multi-wavelength spectral energy distributions (SEDs) of 16 BSS and 2 YSS candidates, within the Swift/UVOT field, to analyze their properties. Out of these, 8 BSS candidates and both the YSS candidates are successfully fitted with single-component SEDs. Five BSS candidates show marginal excess in the near-UV (fractional residual < 0.3 in all but one UVOT filter), whereas three BSS candidates show moderate to significant excess in the near-UV (fractional residual > 0.3 in at least two UVOT filters). We present the properties of the BSS and YSS candidates, estimated based on the SED fits.
{"title":"Characterization of blue and yellow straggler stars of Berkeley 39 using Swift/UVOT","authors":"Komal Chand, Khushboo Rao, Kaushar Vaidya, Anju Panthi","doi":"arxiv-2409.12062","DOIUrl":"https://doi.org/arxiv-2409.12062","url":null,"abstract":"We characterize blue straggler stars (BSS) and yellow straggler stars (YSS)\u0000of an open cluster (OC) Berkeley 39 using multi-wavelength observations\u0000including Swift/UVOT. Our analysis also makes use of ultraviolet (UV) data from\u0000GALEX, optical data from Gaia DR3 and Pan-STARRS, and infrared data from 2MASS,\u0000Spitzer/IRAC, and WISE. Berkeley 39 is a ~6 Gyr old Galactic OC located at a\u0000distance of ~4200 pc. We identify 729 sources as cluster members utilizing a\u0000machine learning algorithm, ML-MOC, on Gaia DR3 data. Of these, 17 sources are\u0000classified as BSS candidates and four as YSS candidates. We construct\u0000multi-wavelength spectral energy distributions (SEDs) of 16 BSS and 2 YSS\u0000candidates, within the Swift/UVOT field, to analyze their properties. Out of\u0000these, 8 BSS candidates and both the YSS candidates are successfully fitted\u0000with single-component SEDs. Five BSS candidates show marginal excess in the\u0000near-UV (fractional residual < 0.3 in all but one UVOT filter), whereas three\u0000BSS candidates show moderate to significant excess in the near-UV (fractional\u0000residual > 0.3 in at least two UVOT filters). We present the properties of the\u0000BSS and YSS candidates, estimated based on the SED fits.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257927","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 trained denoiser autoencoding neural networks on medium resolution simulated optical spectra of late-type stars to demonstrate that the reconstruction of the original flux is possible at a typical relative error of a fraction of a percent down to a typical signal-to-noise ratio of 10 per pixel. We show that relatively simple networks are capable of learning the characteristics of stellar spectra while still flexible enough to adapt to different values of extinction and fluxing imperfections that modifies the overall shape of the continuum, as well as to different values of Doppler shift. Denoised spectra can be used to find initial values for traditional stellar template fitting algorithms and - since evaluation of pre-trained neural networks is significantly faster than traditional template fitting - denoiser networks can be useful when a fast analysis of the noisy spectrum is necessary, for example during observations, between individual exposures.
{"title":"Denoising medium resolution stellar spectra with neural networks","authors":"Balázs Pál, László Dobos","doi":"arxiv-2409.11625","DOIUrl":"https://doi.org/arxiv-2409.11625","url":null,"abstract":"We trained denoiser autoencoding neural networks on medium resolution\u0000simulated optical spectra of late-type stars to demonstrate that the\u0000reconstruction of the original flux is possible at a typical relative error of\u0000a fraction of a percent down to a typical signal-to-noise ratio of 10 per\u0000pixel. We show that relatively simple networks are capable of learning the\u0000characteristics of stellar spectra while still flexible enough to adapt to\u0000different values of extinction and fluxing imperfections that modifies the\u0000overall shape of the continuum, as well as to different values of Doppler\u0000shift. Denoised spectra can be used to find initial values for traditional\u0000stellar template fitting algorithms and - since evaluation of pre-trained\u0000neural networks is significantly faster than traditional template fitting -\u0000denoiser networks can be useful when a fast analysis of the noisy spectrum is\u0000necessary, for example during observations, between individual exposures.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257933","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}
Gayathri Viswanath, Simon C. Ringqvist, Dorian Demars, Markus Janson, Mickaël Bonnefoy, Yuhiko Aoyama, Gabriel-Dominique Marleau, Catherine Dougados, Judit Szulágyi, Thanawuth Thanathibodee
Accretion among planets is a poorly understood phenomenon, due to lack of both observational and theoretical studies. Detection of emission lines from accreting gas giants facilitate detailed investigations into this process. This work presents a detailed analysis of Balmer lines from one of the few known young, planetary-mass objects with observed emission, the isolated L2 dwarf 2MASS J11151597+1937266 with a mass 7-21 Mj and age 5-45 Myr, located at 45+-2 pc. We obtained the first high-resolution (R~50,000) spectrum of the target with VLT/UVES, a spectrograph in the near-UV to visible wavelengths (3200-6800 AA). We report resolved H3-H6 and He I (5875.6 AA) emission in the spectrum. Based on the asymmetric line profiles of H3 and H4, 10% width of H3 (199+-1 km/s), tentative He I 6678 AA emission and indications of a disk from MIR excess, we confirm ongoing accretion at this object. Using the Gaia update of the parallax, we revise its temperature to 1816+-63 K and radius to 1.5+-0.1 Rj. Analysis of observed H I profiles using 1D planet-surface shock model implies a pre-shock gas velocity of v0=120(+80,-40) km/s and a pre-shock density of log(n0/cm^-3)=14(+0,-5). Pre-shock velocity points to a mass of 6(+8,-4) Mj for the target. Combining the H I line luminosities and planetary Lline-Lacc scaling relations, we derive a mass accretion rate of 1.4(+2.8,-0.9)x10^-8 Mj/yr.
由于缺乏观测和理论研究，人们对行星间的吸积现象知之甚少。对正在增殖的气态巨行星发射线的探测有助于对这一过程进行详细研究。这项工作详细分析了为数不多的观测到发射线的年轻行星质量天体之一--孤立的L2矮星2MASS J11151597+1937266的巴尔默线，它的质量为7-21 Mj，年龄为5-45 Myr，位于45+-2pc处。我们利用 VLT/UVES 获得了该目标的第一个高分辨率（R~50,000）光谱，这是一个近紫外到可见光波长（3200-6800AA）的光谱仪。根据H3和H4的不对称线剖面、H3的10%宽度（199+-1km/s）、暂定的He I 6678 AA发射以及来自MIRexcess的圆盘迹象，我们证实了该天体正在进行吸积。利用盖亚更新的视差，我们将其温度修正为1816+-63 K，半径修正为1.5+-0.1Rj。利用一维行星表面冲击模型对观测到的H I剖面进行分析，得出冲击前气体速度为v0=120(+80,-40) km/s，冲击前密度为log(n0/cm^-3)=14(+0,-5)。冲击前速度表明目标质量为 6(+8,-4) Mj。结合 H I 线光度和行星线-Lacc 的比例关系，我们得出质量增殖速率为 1.4(+2.8,-0.9)x10^-8 Mj/年。
{"title":"Exoplanet accretion monitoring spectroscopic survey (ENTROPY) I. Evidence for magnetospheric accretion in the young isolated planetary-mass object 2MASS J11151597+1937266","authors":"Gayathri Viswanath, Simon C. Ringqvist, Dorian Demars, Markus Janson, Mickaël Bonnefoy, Yuhiko Aoyama, Gabriel-Dominique Marleau, Catherine Dougados, Judit Szulágyi, Thanawuth Thanathibodee","doi":"arxiv-2409.12187","DOIUrl":"https://doi.org/arxiv-2409.12187","url":null,"abstract":"Accretion among planets is a poorly understood phenomenon, due to lack of\u0000both observational and theoretical studies. Detection of emission lines from\u0000accreting gas giants facilitate detailed investigations into this process. This\u0000work presents a detailed analysis of Balmer lines from one of the few known\u0000young, planetary-mass objects with observed emission, the isolated L2 dwarf\u00002MASS J11151597+1937266 with a mass 7-21 Mj and age 5-45 Myr, located at 45+-2\u0000pc. We obtained the first high-resolution (R~50,000) spectrum of the target\u0000with VLT/UVES, a spectrograph in the near-UV to visible wavelengths (3200-6800\u0000AA). We report resolved H3-H6 and He I (5875.6 AA) emission in the spectrum.\u0000Based on the asymmetric line profiles of H3 and H4, 10% width of H3 (199+-1\u0000km/s), tentative He I 6678 AA emission and indications of a disk from MIR\u0000excess, we confirm ongoing accretion at this object. Using the Gaia update of\u0000the parallax, we revise its temperature to 1816+-63 K and radius to 1.5+-0.1\u0000Rj. Analysis of observed H I profiles using 1D planet-surface shock model\u0000implies a pre-shock gas velocity of v0=120(+80,-40) km/s and a pre-shock\u0000density of log(n0/cm^-3)=14(+0,-5). Pre-shock velocity points to a mass of\u00006(+8,-4) Mj for the target. Combining the H I line luminosities and planetary\u0000Lline-Lacc scaling relations, we derive a mass accretion rate of\u00001.4(+2.8,-0.9)x10^-8 Mj/yr.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257935","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. G. Sousa, V. Adibekyan, E. Delgado-Mena, N. C. Santos, B. Rojas-Ayala, S. C. Barros, O. D. S. Demangeon, S. Hoyer, G. Israelian, A. Mortier, B. M. T. Soares, M. Tsantaki
SWEET-Cat (Stars With ExoplanETs Catalogue) was originally introduced in 2013, and since then, the number of confirmed exoplanets has increased significantly. A crucial step for a comprehensive understanding of these new worlds is the precise and homogeneous characterization of their host stars. We used a large number of high-resolution spectra to continue the addition of new stellar parameters for planet-host stars in SWEET-Cat following the new detection of exoplanets listed both at the Extrasolar Planets Encyclopedia and at the NASA exoplanet archive. We obtained high-resolution spectra for a significant number of these planet-host stars, either observed by our team or collected through public archives. For FGK stars, the spectroscopic stellar parameters were derived for the spectra following the same homogeneous process using ARES+MOOG as for the previous SWEET-Cat releases. The stellar properties are combined with the planet properties to study possible correlations that could shed more light into the star-planet connection studies. We increase the number of stars with homogeneous parameters by 232 ($sim$ 25% - from 959 to 1191). We then focus on the exoplanets with both mass and radius determined to review the mass-radius relation where we find consistent results with the ones previously reported in the literature. For the massive planets we also revisit the radius anomaly where we confirm a metallicity correlation for the radius anomaly already hinted in previous results.
{"title":"SWEET-Cat: A view on the planetary mass-radius relation","authors":"S. G. Sousa, V. Adibekyan, E. Delgado-Mena, N. C. Santos, B. Rojas-Ayala, S. C. Barros, O. D. S. Demangeon, S. Hoyer, G. Israelian, A. Mortier, B. M. T. Soares, M. Tsantaki","doi":"arxiv-2409.11965","DOIUrl":"https://doi.org/arxiv-2409.11965","url":null,"abstract":"SWEET-Cat (Stars With ExoplanETs Catalogue) was originally introduced in\u00002013, and since then, the number of confirmed exoplanets has increased\u0000significantly. A crucial step for a comprehensive understanding of these new\u0000worlds is the precise and homogeneous characterization of their host stars. We\u0000used a large number of high-resolution spectra to continue the addition of new\u0000stellar parameters for planet-host stars in SWEET-Cat following the new\u0000detection of exoplanets listed both at the Extrasolar Planets Encyclopedia and\u0000at the NASA exoplanet archive. We obtained high-resolution spectra for a\u0000significant number of these planet-host stars, either observed by our team or\u0000collected through public archives. For FGK stars, the spectroscopic stellar\u0000parameters were derived for the spectra following the same homogeneous process\u0000using ARES+MOOG as for the previous SWEET-Cat releases. The stellar properties\u0000are combined with the planet properties to study possible correlations that\u0000could shed more light into the star-planet connection studies. We increase the\u0000number of stars with homogeneous parameters by 232 ($sim$ 25% - from 959 to\u00001191). We then focus on the exoplanets with both mass and radius determined to\u0000review the mass-radius relation where we find consistent results with the ones\u0000previously reported in the literature. For the massive planets we also revisit\u0000the radius anomaly where we confirm a metallicity correlation for the radius\u0000anomaly already hinted in previous results.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"208 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269172","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}
H. Islam, N. Schwadron, E. Moebius, F. Rahmanifard, J. M. Sokol, A. Galli, D. J. McComas, P. Wurz, S. A. Fuselier, K. Fairchild, D. Heirtzler
The IBEX-Lo instrument on the Interstellar Boundary Explorer (IBEX) mission observes primary and secondary interstellar helium in its 4 lowest energy steps. Observations of these helium populations have been systematically analyzed and compared to simulations using the analytic full integration of neutrals model (aFINM). A systematic difference is observed between the simulations and observations of secondary helium during solar cycle (SC) 24. We show that elastic scattering of primary helium by solar wind protons, which redistributes atoms from the core of the flux distribution, provides an explanation of the observed divergence from simulations. We verify that elastic scattering forms a halo in the wings of the primary He distribution in the spin-angle direction. Correcting the simulation for the effects of elastic scattering requires an increase of the estimated density of primary helium compared to previous estimates by Ulysses/GAS. Thus, based on our analysis of IBEX observations and $chi ^2$ minimization of simulation data that include the effects of elastic scattering, any estimation of neutral interstellar helium density at 1 AU by direct detection of the peak flux of neutral helium needs to be adjusted by $~sim$ 10%
{"title":"IBEX Observations of Elastic Scattering of Interstellar Helium by Solar Wind Particles","authors":"H. Islam, N. Schwadron, E. Moebius, F. Rahmanifard, J. M. Sokol, A. Galli, D. J. McComas, P. Wurz, S. A. Fuselier, K. Fairchild, D. Heirtzler","doi":"arxiv-2409.11784","DOIUrl":"https://doi.org/arxiv-2409.11784","url":null,"abstract":"The IBEX-Lo instrument on the Interstellar Boundary Explorer (IBEX) mission\u0000observes primary and secondary interstellar helium in its 4 lowest energy\u0000steps. Observations of these helium populations have been systematically\u0000analyzed and compared to simulations using the analytic full integration of\u0000neutrals model (aFINM). A systematic difference is observed between the\u0000simulations and observations of secondary helium during solar cycle (SC) 24. We\u0000show that elastic scattering of primary helium by solar wind protons, which\u0000redistributes atoms from the core of the flux distribution, provides an\u0000explanation of the observed divergence from simulations. We verify that elastic\u0000scattering forms a halo in the wings of the primary He distribution in the\u0000spin-angle direction. Correcting the simulation for the effects of elastic\u0000scattering requires an increase of the estimated density of primary helium\u0000compared to previous estimates by Ulysses/GAS. Thus, based on our analysis of\u0000IBEX observations and $chi ^2$ minimization of simulation data that include\u0000the effects of elastic scattering, any estimation of neutral interstellar\u0000helium density at 1 AU by direct detection of the peak flux of neutral helium\u0000needs to be adjusted by $~sim$ 10%","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257931","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}
Sai Prathyusha Malla, Dennis Stello, Benjamin T. Monet, Daniel Huber, Marc Hon, Timothy R. Bedding, Claudia Reyes, Daniel R. Hey
One way to understand planet formation is through studying the correlations between planet occurrence rates and stellar mass. However, measuring stellar mass in the red giant regime is very difficult. In particular, the spectroscopic masses of certain evolved stars, often referred to as "retired A-stars", have been questioned in the literature. Efforts to resolve this mass controversy using spectroscopy, interferometry and asteroseismology have so far been inconclusive. A recent ensemble study found a mass-dependent mass offset, but the result was based on only 16 stars. With NASA's Transiting Exoplanet Survey Satellite (TESS), we expand the investigation of the mass discrepancy to a total of 92 low-luminosity stars, synonymous with the retired A-stars. We measure their characteristic oscillation frequency, $mathrm{nu}_{mathrm{max}}$, and the large frequency separation, $mathrm{Deltanu}$, from their TESS photometric time series. Using these measurements and asteroseismic scaling relations, we derive asteroseismic masses and compare them with spectroscopic masses from five surveys, to comprehensively study the alleged mass-dependent mass offset. We find a mass offset between spectroscopy and seismology that increases with stellar mass. However, we note that adopting the seismic mass scale does not have a significant effect on the planet occurrence-mass-metallicity correlation for the so-called retired A-stars. We also report seismic measurements and masses for 157 higher luminosity giants (mostly helium-core-burning) from the spectroscopic surveys.
了解行星形成的一种方法是研究行星出现率与恒星质量之间的相关性。然而，测量红巨星体系中的恒星质量非常困难。特别是某些演化恒星（通常被称为 "退休 A 星"）的光谱质量在文献中一直受到质疑。迄今为止，利用光谱学、干涉测量学和小行星地震学来解决这一质量争议的努力还没有得出结论。最近的一项集合研究发现了与质量相关的质量偏移，但这一结果只基于 16 颗恒星。借助美国宇航局的凌日系外行星勘测卫星（TESS），我们将对质量偏差的研究扩大到了总共 92 颗低亮度恒星，它们与已退役的 A 星同义。我们从它们的TESS测光时间序列中测量了它们的特征振荡频率（$mathrm{nu}_{mathrm{max}}$）和大频率间隔（$mathrm{Deltanu}$）。利用这些测量数据和小行星地震比例关系，我们得出了小行星地震质量，并将它们与来自五次巡天的光谱质量进行比较，以全面研究所谓的质量偏移。我们发现光谱学和地震学之间的质量偏移随着恒星质量的增加而增加。不过，我们注意到，对于所谓的退役 A 星，采用地震质量标度对行星出现-质量-金属性的相关性并没有显著影响。我们还报告了来自光谱巡天的 157 个较高亮度巨星（大多为氦核燃烧型）的地震测量结果和质量。
{"title":"Benchmarking the spectroscopic masses of 249 evolved stars using asteroseismology with TESS","authors":"Sai Prathyusha Malla, Dennis Stello, Benjamin T. Monet, Daniel Huber, Marc Hon, Timothy R. Bedding, Claudia Reyes, Daniel R. Hey","doi":"arxiv-2409.11736","DOIUrl":"https://doi.org/arxiv-2409.11736","url":null,"abstract":"One way to understand planet formation is through studying the correlations\u0000between planet occurrence rates and stellar mass. However, measuring stellar\u0000mass in the red giant regime is very difficult. In particular, the\u0000spectroscopic masses of certain evolved stars, often referred to as \"retired\u0000A-stars\", have been questioned in the literature. Efforts to resolve this mass\u0000controversy using spectroscopy, interferometry and asteroseismology have so far\u0000been inconclusive. A recent ensemble study found a mass-dependent mass offset,\u0000but the result was based on only 16 stars. With NASA's Transiting Exoplanet\u0000Survey Satellite (TESS), we expand the investigation of the mass discrepancy to\u0000a total of 92 low-luminosity stars, synonymous with the retired A-stars. We\u0000measure their characteristic oscillation frequency,\u0000$mathrm{nu}_{mathrm{max}}$, and the large frequency separation,\u0000$mathrm{Deltanu}$, from their TESS photometric time series. Using these\u0000measurements and asteroseismic scaling relations, we derive asteroseismic\u0000masses and compare them with spectroscopic masses from five surveys, to\u0000comprehensively study the alleged mass-dependent mass offset. We find a mass\u0000offset between spectroscopy and seismology that increases with stellar mass.\u0000However, we note that adopting the seismic mass scale does not have a\u0000significant effect on the planet occurrence-mass-metallicity correlation for\u0000the so-called retired A-stars. We also report seismic measurements and masses\u0000for 157 higher luminosity giants (mostly helium-core-burning) from the\u0000spectroscopic surveys.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257930","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}
Daye Lim, Tom Van Doorsselaere, Valery M. Nakariakov, Dmitrii Y. Kolotkov, Yuhang Gao, David Berghmans
Context. Recent observations of decayless transverse oscillations have shown two branches in the relationship between periods and loop lengths. One is a linear relationship, interpreted as a standing mode. The other shows almost no correlation and has not yet been interpreted conclusively. Aims. We investigated the undersampling effect on observed periods of decayless oscillations. Methods. We considered oscillating coronal loops that closely follow the observed loop length distribution. Assuming that all oscillations are standing waves, we modeled a signal that represents decayless oscillations where the period is proportional to the loop length and the amplitude and phase are randomly drawn. A downsampled signal was generated from the original signal by considering different sample rates that mimic temporal cadences of telescopes, and periods for sampled signals were analysed using the fast Fourier transform. Results. When the sampling cadence is getting closer to the actual oscillation period, a tendency for overestimating periods in short loops is enhanced. The relationship between loop lengths and periods of the sampled signals shows the two branches as in the observation. Conclusions. We find that long periods of decayless oscillations occurring in short loops could be the result of undersampling.
{"title":"Undersampling effects on observed periods of coronal oscillations","authors":"Daye Lim, Tom Van Doorsselaere, Valery M. Nakariakov, Dmitrii Y. Kolotkov, Yuhang Gao, David Berghmans","doi":"arxiv-2409.12095","DOIUrl":"https://doi.org/arxiv-2409.12095","url":null,"abstract":"Context. Recent observations of decayless transverse oscillations have shown\u0000two branches in the relationship between periods and loop lengths. One is a\u0000linear relationship, interpreted as a standing mode. The other shows almost no\u0000correlation and has not yet been interpreted conclusively. Aims. We\u0000investigated the undersampling effect on observed periods of decayless\u0000oscillations. Methods. We considered oscillating coronal loops that closely\u0000follow the observed loop length distribution. Assuming that all oscillations\u0000are standing waves, we modeled a signal that represents decayless oscillations\u0000where the period is proportional to the loop length and the amplitude and phase\u0000are randomly drawn. A downsampled signal was generated from the original signal\u0000by considering different sample rates that mimic temporal cadences of\u0000telescopes, and periods for sampled signals were analysed using the fast\u0000Fourier transform. Results. When the sampling cadence is getting closer to the\u0000actual oscillation period, a tendency for overestimating periods in short loops\u0000is enhanced. The relationship between loop lengths and periods of the sampled\u0000signals shows the two branches as in the observation. Conclusions. We find that\u0000long periods of decayless oscillations occurring in short loops could be the\u0000result of undersampling.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269169","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}
Kamber R. Schwarz, Matthias Samland, Göran Olofsson, Thomas Henning, Andrew Sellek, Manuel Güdel, Benoît Tabone, Inga Kamp, Pierre-Olivier Lagage, Ewine F. van Dishoeck, Alessio Caratti o Garatti, Adrian M. Glauser, Tom P. Ray, Aditya M. Arabhavi, Valentin Christiaens, Riccardo Franceschi, Danny Gasman, Sierra L. Grant, Jayatee Kanwar, Till Kaeufer, Nicolas T. Kurtovic, Giulia Perotti, Milou Temmink, Marissa Vlasblom
The removal of angular momentum from protostellar systems drives accretion onto the central star and may drive the dispersal of the protoplanetary disk. Winds and jets can contribute to removing angular momentum from the disk, though the dominant process remain unclear. To date, observational studies of resolved disk winds have mostly targeted highly inclined disks. We report the detection of extended H2 and [Ne II] emission toward the young stellar object SY Cha with the JWST Mid-InfraRed Instrument Medium Resolution Spectrometer (MIRI-MRS). This is one of the first polychromatic detections of extended H2 toward a moderately inclined, i=51.1 degrees, Class II source. We measure the semi-opening angle of the H2 emission as well as build a rotation diagram to determine the H2 excitation temperature and abundance. We find a wide semi-opening angle, high temperature, and low column density for the H2 emission, all of which are characteristic of a disk wind. These observations demonstrate MIRI-MRS's utility in expanding studies of resolved disk winds beyond edge-on sources.
原恒星系统角动量的去除会推动中心恒星的吸积，并可能推动原行星盘的扩散。迄今为止，对已分辨盘风的观测研究大多以高倾角盘为目标。我们报告了利用 JWST Mid-Infrared Instrument Medium Resolution Spectrometer（MIRI-MRS）对年轻恒星天体SY Cha 的 H2 和 [Ne II] 延伸发射的探测结果。这是首次多色探测到一个中等倾角（i=51.1度）的II类源的扩展H2。我们测量了H2发射的半开角，并绘制了旋转图，以确定H2的激发温度和丰度。我们发现 H2 发射的半开角大、温度高、柱密度低，这些都是盘风的特征。这些观测结果证明了 MIRI-MRS 在扩大对边缘源以外的解析盘风研究方面的作用。
{"title":"MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind Toward SY Cha","authors":"Kamber R. Schwarz, Matthias Samland, Göran Olofsson, Thomas Henning, Andrew Sellek, Manuel Güdel, Benoît Tabone, Inga Kamp, Pierre-Olivier Lagage, Ewine F. van Dishoeck, Alessio Caratti o Garatti, Adrian M. Glauser, Tom P. Ray, Aditya M. Arabhavi, Valentin Christiaens, Riccardo Franceschi, Danny Gasman, Sierra L. Grant, Jayatee Kanwar, Till Kaeufer, Nicolas T. Kurtovic, Giulia Perotti, Milou Temmink, Marissa Vlasblom","doi":"arxiv-2409.11176","DOIUrl":"https://doi.org/arxiv-2409.11176","url":null,"abstract":"The removal of angular momentum from protostellar systems drives accretion\u0000onto the central star and may drive the dispersal of the protoplanetary disk.\u0000Winds and jets can contribute to removing angular momentum from the disk,\u0000though the dominant process remain unclear. To date, observational studies of\u0000resolved disk winds have mostly targeted highly inclined disks. We report the\u0000detection of extended H2 and [Ne II] emission toward the young stellar object\u0000SY Cha with the JWST Mid-InfraRed Instrument Medium Resolution Spectrometer\u0000(MIRI-MRS). This is one of the first polychromatic detections of extended H2\u0000toward a moderately inclined, i=51.1 degrees, Class II source. We measure the\u0000semi-opening angle of the H2 emission as well as build a rotation diagram to\u0000determine the H2 excitation temperature and abundance. We find a wide\u0000semi-opening angle, high temperature, and low column density for the H2\u0000emission, all of which are characteristic of a disk wind. These observations\u0000demonstrate MIRI-MRS's utility in expanding studies of resolved disk winds\u0000beyond edge-on sources.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257977","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}
Many accretion discs have been found to be distorted: either warped due a misalignment in the system, or non-circular as a result of orbital eccentricity or tidal deformation by a binary companion. Warped, eccentric, and tidally distorted discs are not in vertical hydrostatic equilibrium, and thus exhibit vertical oscillations in the direction perpendicular to the disc, a phenomenon that is absent in circular and flat discs. In extreme cases, this vertical motion is manifested as a vertical `bouncing' of the gas, potentially leading to shocks and heating, as observed in recent global numerical simulations. In this paper we isolate the mechanics of vertical disc oscillations by means of quasi-2D and fully 3D hydrodynamic local (shearing-box) models. To determine the numerical and physical dissipation mechanisms at work during an oscillation we start by investigating unforced oscillations, examining the effect of initial oscillation amplitude, as well as resolution, boundary conditions, and vertical box size on the dissipation and energetics of the oscillations. We then drive the oscillations by introducing a time-dependent gravitational potential. A key result is that even a purely vertically oscillating disc is (parametrically) unstable to developing inertial waves, as we confirm through a linear stability analysis. The most important of these has the character of a bending wave, whose radial wavelength depends on the frequency of the vertical oscillation. The nonlinear phase of the instability exhibits shocks, which dampen the oscillations, although energy can also flow from the bending wave back to the vertical oscillation.
{"title":"Instability and warping in vertically oscillating accretion discs","authors":"Loren E. Held, Gordon I. Ogilvie","doi":"arxiv-2409.11490","DOIUrl":"https://doi.org/arxiv-2409.11490","url":null,"abstract":"Many accretion discs have been found to be distorted: either warped due a\u0000misalignment in the system, or non-circular as a result of orbital eccentricity\u0000or tidal deformation by a binary companion. Warped, eccentric, and tidally\u0000distorted discs are not in vertical hydrostatic equilibrium, and thus exhibit\u0000vertical oscillations in the direction perpendicular to the disc, a phenomenon\u0000that is absent in circular and flat discs. In extreme cases, this vertical\u0000motion is manifested as a vertical `bouncing' of the gas, potentially leading\u0000to shocks and heating, as observed in recent global numerical simulations. In\u0000this paper we isolate the mechanics of vertical disc oscillations by means of\u0000quasi-2D and fully 3D hydrodynamic local (shearing-box) models. To determine\u0000the numerical and physical dissipation mechanisms at work during an oscillation\u0000we start by investigating unforced oscillations, examining the effect of\u0000initial oscillation amplitude, as well as resolution, boundary conditions, and\u0000vertical box size on the dissipation and energetics of the oscillations. We\u0000then drive the oscillations by introducing a time-dependent gravitational\u0000potential. A key result is that even a purely vertically oscillating disc is\u0000(parametrically) unstable to developing inertial waves, as we confirm through a\u0000linear stability analysis. The most important of these has the character of a\u0000bending wave, whose radial wavelength depends on the frequency of the vertical\u0000oscillation. The nonlinear phase of the instability exhibits shocks, which\u0000dampen the oscillations, although energy can also flow from the bending wave\u0000back to the vertical oscillation.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257932","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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