Edward T Stevenson, Álvaro Ribas, Jessica Speedie, Richard A Booth, C. Clarke
ALMA (Atacama Large Millimetre/submillimetre Array) observations of the thermal emission from protoplanetary disc dust have revealed a wealth of substructures that could evidence embedded planets, but planet-driven spirals, one of the more compelling lines of evidence, remain relatively rare. Existing works have focused on detecting these spirals using methods that operate in image space. Here, we explore the planet detection capabilities of fitting planet-driven spirals to disc observations directly in visibility space. We test our method on synthetic ALMA observations of planet-containing model discs for a range of disc/observational parameters, finding it significantly outperforms image residuals in identifying spirals in these observations and is able to identify spirals in regions of the parameter space in which no gaps are detected. These tests suggest that a visibility-space fitting approach warrants further investigation and may be able to find planet-driven spirals in observations that have not yet been found with existing approaches. We also test our method on six discs in the Taurus molecular cloud observed with ALMA at 1.33 mm, but find no evidence for planet-driven spirals. We find that the minimum planet masses necessary to drive detectable spirals range from ≈0.03 to 0.5 MJup over orbital radii of 10 to 100 au, with planet masses below these thresholds potentially hiding in such disc observations. Conversely, we suggest that planets ≳ 0.5 to 1 MJup can likely be ruled out over orbital radii of ≈20 to 60 au on the grounds that we would have detected them if they were present.
ALMA（阿塔卡马大型毫米波/亚毫米波阵列）对原行星盘尘埃热辐射的观测揭示了大量可能证明内含行星的子结构，但行星驱动的螺旋现象作为更有说服力的证据之一，仍然相对罕见。现有研究主要集中在使用图像空间的方法来探测这些螺旋。在这里，我们将探索直接在可见度空间内将行星驱动的螺旋拟合到圆盘观测中的行星探测能力。我们在一系列圆盘/观测参数下的含行星模型圆盘的合成 ALMA 观测数据上测试了我们的方法，发现它在这些观测数据中识别螺旋形行星的能力明显优于图像残差，并且能够在参数空间中检测不到间隙的区域识别螺旋形行星。这些测试表明，可见度空间拟合方法值得进一步研究，它可能能够在观测中发现现有方法尚未发现的行星驱动的螺旋现象。我们还在用 ALMA 在 1.33 毫米观测到的金牛座分子云中的六个圆盘上测试了我们的方法，但没有发现行星驱动螺旋的证据。我们发现，在 10 到 100 au 的轨道半径范围内，驱动可探测到的螺旋现象所需的行星质量最小值为 ≈0.03 到 0.5 MJup，低于这些阈值的行星质量有可能隐藏在此类圆盘观测中。相反，我们认为，在轨道半径≈20 到 60 au 的范围内，0.5 到 1 MJup 的行星很可能被排除在外，因为如果它们存在，我们也会探测到。
{"title":"Searching for planet-driven dust spirals in ALMA visibilities","authors":"Edward T Stevenson, Álvaro Ribas, Jessica Speedie, Richard A Booth, C. Clarke","doi":"10.1093/mnras/stae1094","DOIUrl":"https://doi.org/10.1093/mnras/stae1094","url":null,"abstract":"\u0000 ALMA (Atacama Large Millimetre/submillimetre Array) observations of the thermal emission from protoplanetary disc dust have revealed a wealth of substructures that could evidence embedded planets, but planet-driven spirals, one of the more compelling lines of evidence, remain relatively rare. Existing works have focused on detecting these spirals using methods that operate in image space. Here, we explore the planet detection capabilities of fitting planet-driven spirals to disc observations directly in visibility space. We test our method on synthetic ALMA observations of planet-containing model discs for a range of disc/observational parameters, finding it significantly outperforms image residuals in identifying spirals in these observations and is able to identify spirals in regions of the parameter space in which no gaps are detected. These tests suggest that a visibility-space fitting approach warrants further investigation and may be able to find planet-driven spirals in observations that have not yet been found with existing approaches. We also test our method on six discs in the Taurus molecular cloud observed with ALMA at 1.33 mm, but find no evidence for planet-driven spirals. We find that the minimum planet masses necessary to drive detectable spirals range from ≈0.03 to 0.5 MJup over orbital radii of 10 to 100 au, with planet masses below these thresholds potentially hiding in such disc observations. Conversely, we suggest that planets ≳ 0.5 to 1 MJup can likely be ruled out over orbital radii of ≈20 to 60 au on the grounds that we would have detected them if they were present.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"92 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140659397","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}
Jie Yu, Luca Casagrande, I. Ciucă, Yuan-Sen Ting, S. J. Murphy, Boquan Chen
Young α–rich (YAR) stars within the old Galactic thick disk exhibit a dual characteristic of relative youth determined with asteroseismology and abundance enhancement in α elements measured from high–resolution spectroscopy. The youth origin of YAR stars has been proposed to be binary evolution via mass transfer or stellar mergers. If that is the case, YAR stars should spin rapidly and thus be magnetically active, because they are mass and angular momentum gainers. In this study, to seek this binary footprint we select YAR stars on the main–sequence turn–off or the subgiant branch (MSTO–SGB) from APOGEE DR17, whose ages and projected rotation velocities (vsini) can be precisely measured. With APOGEE vsini and LAMOST spectra, we find that YAR stars are indeed fast rotators and magnetically active. In addition, we observe low [C/N] ratios and high Gaia RUWE in some YAR stars, suggesting that these MSTO–SGB stars probably have experienced mass transfer from red–giant companions. Our findings underscore that magnetic activity can serve as a valuable tool for probing the binary evolution for other chemically peculiar stars, such as red giants with lithium anomalies and carbon–enhanced metal–poor stars.
{"title":"New evidence of binarity in young α–rich turn-off and subgiant stars: Fast rotation and strong magnetic activity","authors":"Jie Yu, Luca Casagrande, I. Ciucă, Yuan-Sen Ting, S. J. Murphy, Boquan Chen","doi":"10.1093/mnras/stae1091","DOIUrl":"https://doi.org/10.1093/mnras/stae1091","url":null,"abstract":"\u0000 Young α–rich (YAR) stars within the old Galactic thick disk exhibit a dual characteristic of relative youth determined with asteroseismology and abundance enhancement in α elements measured from high–resolution spectroscopy. The youth origin of YAR stars has been proposed to be binary evolution via mass transfer or stellar mergers. If that is the case, YAR stars should spin rapidly and thus be magnetically active, because they are mass and angular momentum gainers. In this study, to seek this binary footprint we select YAR stars on the main–sequence turn–off or the subgiant branch (MSTO–SGB) from APOGEE DR17, whose ages and projected rotation velocities (vsini) can be precisely measured. With APOGEE vsini and LAMOST spectra, we find that YAR stars are indeed fast rotators and magnetically active. In addition, we observe low [C/N] ratios and high Gaia RUWE in some YAR stars, suggesting that these MSTO–SGB stars probably have experienced mass transfer from red–giant companions. Our findings underscore that magnetic activity can serve as a valuable tool for probing the binary evolution for other chemically peculiar stars, such as red giants with lithium anomalies and carbon–enhanced metal–poor stars.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"109 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140669791","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}
Low-mass X-ray binaries (LMXBs) with neutron stars show quite different features which depend on the rate of mass transfer from the donor star. With a high transfer rate the Z sources are in a persistent soft spectral state, with a moderate rate the transient Atoll sources have outburst cycles like the black hole X-ray binaries. The observations document very long outburst recurrence times for quite a number of sources. We follow with our computations the evolution of the accretion disc until the onset of the ionization instability. For sources with a low mass transfer rate the accumulation of matter in the disc is essentially reduced due to the continuous evaporation of matter from the disc to the coronal flow. Different mass transfer rates result in nearly the same amount of matter accumulated for the outburst which means the outburst properties are similar for sources with short and sources with long outburst cycles, contrary to some expectations. Then of systems with long recurrence time less sources will be detected and the total population of LMXBs could be larger than it appears. This would relieve the apparent problem that the observed number of LMXBs as progenitors of millisecond pulsars (MSP) is too small compared to the number of MSP. Concerning the few quasi-persistent sources with year-long soft states we argue that these states are not outbursts, but quasi-stationary hot states as in Z sources.
带有中子星的低质量 X 射线双星（LMXBs）显示出截然不同的特征，这取决于来自供体星的质量转移率。转移率高时，Z 源处于持续的软光谱状态；转移率适中时，瞬态阿托环源就会像黑洞 X 射线双星一样出现爆发周期。观测结果表明，很多星源的爆发周期都很长。我们通过计算跟踪了吸积盘的演变过程，直到电离不稳定性开始出现。对于质量转移率较低的星源，由于物质不断从圆盘蒸发到日冕流，物质在圆盘中的积累基本上减少了。不同的质量转移率导致爆发时积累的物质数量几乎相同，这意味着爆发周期短的源和爆发周期长的源的爆发特性相似，这与某些预期相反。那么，在重复周期长的系统中，被探测到的源会更少，LMXB 的总数可能比表面上看起来的要大。这将缓解一个明显的问题，即观测到的作为毫秒脉冲星（MSP）祖先的 LMXB 的数量与 MSP 的数量相比太少了。关于少数几个具有长达一年的软状态的准恒星源，我们认为这些状态并不是爆发，而是像 Z 源那样的准稳态热状态。
{"title":"A large population of neutron star low-mass X-ray binaries with long outburst recurrence time?","authors":"E. Meyer-Hofmeister, Huaqing Cheng, B. F. Liu","doi":"10.1093/mnras/stae1056","DOIUrl":"https://doi.org/10.1093/mnras/stae1056","url":null,"abstract":"\u0000 Low-mass X-ray binaries (LMXBs) with neutron stars show quite different features which depend on the rate of mass transfer from the donor star. With a high transfer rate the Z sources are in a persistent soft spectral state, with a moderate rate the transient Atoll sources have outburst cycles like the black hole X-ray binaries. The observations document very long outburst recurrence times for quite a number of sources. We follow with our computations the evolution of the accretion disc until the onset of the ionization instability. For sources with a low mass transfer rate the accumulation of matter in the disc is essentially reduced due to the continuous evaporation of matter from the disc to the coronal flow. Different mass transfer rates result in nearly the same amount of matter accumulated for the outburst which means the outburst properties are similar for sources with short and sources with long outburst cycles, contrary to some expectations. Then of systems with long recurrence time less sources will be detected and the total population of LMXBs could be larger than it appears. This would relieve the apparent problem that the observed number of LMXBs as progenitors of millisecond pulsars (MSP) is too small compared to the number of MSP. Concerning the few quasi-persistent sources with year-long soft states we argue that these states are not outbursts, but quasi-stationary hot states as in Z sources.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"130 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140668882","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}
NGC 4395 is a dwarf Seyfert 1 galaxy with a possible intermediate-mass black hole of several $rm {10^4}$ solar masses in its center. As a well-studied object, its broad line region size has been measured via H$rm {alpha }$ time lag in numerous spectroscopic reverberation mapping (SRM) and narrow-band photometric reverberation mapping (PRM) campaigns. Here we present its H$rm {alpha }$ time lag measurement using broad-band photometric data, with the application of our newly-developed ICCF-Cut method as well as the JAVELIN and χ2 methods. utilizing the minute-cadence multi-band light curves obtained from the $rm {2}$m FTN and $rm {10.4}$m GTC telescopes in recent works, we measured its H$rm {alpha }$ lag as approximately 40 ∼ 90 minutes from broad-band PRM. With the H$rm {alpha }$ emission line velocity dispersion, we calculated its central black hole mass as $rm M_{rm BH} = (8pm 4) times 10^3, M_{rm odot }$. These results are comparable with previous results obtained by narrow-band PRM and SRM, providing further support to an intermediate-mass black hole in NGC 4395. In addition, our study also validates the ICCF-Cut as an effective method for broad-band PRM, which holds the potential for widespread application in the era of large multi-epoch, high-cadence photometric surveys.
{"title":"Hα reverberation mapping from broad-band photometry of dwarf seyfert 1 galaxy NGC 4395","authors":"Huapeng Gu, Xue-Bing Wu, Yuhan Wen, Qinchun Ma, Hengxiao Guo","doi":"10.1093/mnras/stae1063","DOIUrl":"https://doi.org/10.1093/mnras/stae1063","url":null,"abstract":"\u0000 NGC 4395 is a dwarf Seyfert 1 galaxy with a possible intermediate-mass black hole of several $rm {10^4}$ solar masses in its center. As a well-studied object, its broad line region size has been measured via H$rm {alpha }$ time lag in numerous spectroscopic reverberation mapping (SRM) and narrow-band photometric reverberation mapping (PRM) campaigns. Here we present its H$rm {alpha }$ time lag measurement using broad-band photometric data, with the application of our newly-developed ICCF-Cut method as well as the JAVELIN and χ2 methods. utilizing the minute-cadence multi-band light curves obtained from the $rm {2}$m FTN and $rm {10.4}$m GTC telescopes in recent works, we measured its H$rm {alpha }$ lag as approximately 40 ∼ 90 minutes from broad-band PRM. With the H$rm {alpha }$ emission line velocity dispersion, we calculated its central black hole mass as $rm M_{rm BH} = (8pm 4) times 10^3, M_{rm odot }$. These results are comparable with previous results obtained by narrow-band PRM and SRM, providing further support to an intermediate-mass black hole in NGC 4395. In addition, our study also validates the ICCF-Cut as an effective method for broad-band PRM, which holds the potential for widespread application in the era of large multi-epoch, high-cadence photometric surveys.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"41 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140675981","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}
J. Alday, S. Aoki, C. DeWitt, F. Montmessin, J. A. Holmes, M. Patel, J. Mason, T. Encrenaz, M. J. Richter, P. G. J. Irwin, F. Daerden, N. Terada, H. Nakagawa
Isotopic ratios in water vapour carry important information about the water reservoir on Mars. Localised variations in these ratios can inform us about the water cycle and surface-atmosphere exchanges. On the other hand, the global isotopic composition of the atmosphere carries the imprints of the long-term fractionation, providing crucial information about the early water reservoir and its evolution throughout history. Here, we report the analysis of measurements of the D/H and 18O/16O isotopic ratios in water vapour in different seasons (LS = 15○, 127○, 272○, 305○) made with SOFIA/EXES. These measurements, free of telluric absorption, provide a unique tool for constraining the global isotopic composition of Martian water vapour. We find the maximum planetary D/H ratio in our observations during the northern summer (D/H = 5.2 ± 0.2 with respect to the Vienna Standard Mean Ocean Water, VSMOW) and to exhibit relatively small variations throughout the year (D/H = 5.0 ± 0.2 and 4.3 ± 0.4 VSMOW during the northern winter and spring, respectively), which are to first order consistent though noticeably larger than the expectations from condensation-induced fractionation. Our measurements reveal the annually-averaged isotopic composition of water vapour to be consistent with D/H = 5.0 ± 0.2 and 18O/16O = 1.09 Â ± 0.08 VSMOW. In addition, based on a comparison between the SOFIA/EXES measurements and the predictions from a Global Climate Model, we estimate the D/H in the northern polar ice cap to be $sim 5%$ larger than that in the atmospheric reservoir (D/Hice = 5.3 ± 0.3 VSMOW).
{"title":"Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES","authors":"J. Alday, S. Aoki, C. DeWitt, F. Montmessin, J. A. Holmes, M. Patel, J. Mason, T. Encrenaz, M. J. Richter, P. G. J. Irwin, F. Daerden, N. Terada, H. Nakagawa","doi":"10.1093/mnras/stae1067","DOIUrl":"https://doi.org/10.1093/mnras/stae1067","url":null,"abstract":"\u0000 Isotopic ratios in water vapour carry important information about the water reservoir on Mars. Localised variations in these ratios can inform us about the water cycle and surface-atmosphere exchanges. On the other hand, the global isotopic composition of the atmosphere carries the imprints of the long-term fractionation, providing crucial information about the early water reservoir and its evolution throughout history. Here, we report the analysis of measurements of the D/H and 18O/16O isotopic ratios in water vapour in different seasons (LS = 15○, 127○, 272○, 305○) made with SOFIA/EXES. These measurements, free of telluric absorption, provide a unique tool for constraining the global isotopic composition of Martian water vapour. We find the maximum planetary D/H ratio in our observations during the northern summer (D/H = 5.2 ± 0.2 with respect to the Vienna Standard Mean Ocean Water, VSMOW) and to exhibit relatively small variations throughout the year (D/H = 5.0 ± 0.2 and 4.3 ± 0.4 VSMOW during the northern winter and spring, respectively), which are to first order consistent though noticeably larger than the expectations from condensation-induced fractionation. Our measurements reveal the annually-averaged isotopic composition of water vapour to be consistent with D/H = 5.0 ± 0.2 and 18O/16O = 1.09 Â ± 0.08 VSMOW. In addition, based on a comparison between the SOFIA/EXES measurements and the predictions from a Global Climate Model, we estimate the D/H in the northern polar ice cap to be $sim 5%$ larger than that in the atmospheric reservoir (D/Hice = 5.3 ± 0.3 VSMOW).","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"15 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674135","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 predominant formation channel of hot Jupiters remain a puzzle in exoplanet science. One potential way to distinguish the different mechanisms is to study the characteristics of close-in companions to hot Jupiters. In this study, our main focus is to investigate the post-disk evolution of planetary systems initially composed of one Jupiter and several super-Earths through numerical N-body simulations spanning a period of 107 years. By tracing the evolution of each planetary system, we find that only 5.6% of the systems remain stable. Dynamical instabilities are more prevalent in systems with less massive super-Earths and those containing hot Jupiters. Our findings uncover a positive correlation between the presence of close-in companions and the orbital periods of the giant planets. Specifically, we find that approximately 10.9% ± 1.9% of hot Jupiters and 36.4% ± 1.8% of warm Jupiters have close-in companions after 107 years. Moreover, extending the integration time to 108 years reveals that only 1.4%±1.0% of hot Jupiters and 20.3%±2.2% of warm Jupiters host close-in companions. We also investigate the effects of general relativistic, tidal dissipation, and initial spacing between Jupiters and their neighboring planets on the frequency of close-in companions for these short period Jupiters. Our simulations suggest that the general relativity effect plays a crucial role in contributing to the isolation of hot Jupiters. Furthermore, we observe that the more compact the planetary systems are initially, the less likely it is for Jupiter to host close-in companions.
{"title":"Dynamical Instabilities in Post-Disk Evolution: Hot Jupiters Left Isolated","authors":"Ying He, Dong-Hong Wu, Sheng Jin","doi":"10.1093/mnras/stae1076","DOIUrl":"https://doi.org/10.1093/mnras/stae1076","url":null,"abstract":"\u0000 The predominant formation channel of hot Jupiters remain a puzzle in exoplanet science. One potential way to distinguish the different mechanisms is to study the characteristics of close-in companions to hot Jupiters. In this study, our main focus is to investigate the post-disk evolution of planetary systems initially composed of one Jupiter and several super-Earths through numerical N-body simulations spanning a period of 107 years. By tracing the evolution of each planetary system, we find that only 5.6% of the systems remain stable. Dynamical instabilities are more prevalent in systems with less massive super-Earths and those containing hot Jupiters. Our findings uncover a positive correlation between the presence of close-in companions and the orbital periods of the giant planets. Specifically, we find that approximately 10.9% ± 1.9% of hot Jupiters and 36.4% ± 1.8% of warm Jupiters have close-in companions after 107 years. Moreover, extending the integration time to 108 years reveals that only 1.4%±1.0% of hot Jupiters and 20.3%±2.2% of warm Jupiters host close-in companions. We also investigate the effects of general relativistic, tidal dissipation, and initial spacing between Jupiters and their neighboring planets on the frequency of close-in companions for these short period Jupiters. Our simulations suggest that the general relativity effect plays a crucial role in contributing to the isolation of hot Jupiters. Furthermore, we observe that the more compact the planetary systems are initially, the less likely it is for Jupiter to host close-in companions.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"3 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140673737","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}
Michele Bertoldo-Coelho, R. Riffel, Marina Trevisan, N. Dametto, L. Dahmer-Hahn, Paula Coelho, Lucimara P. Martins, D. Ruschel-Dutra, A. Vazdekis, Alberto Rodr'iguez-Ardila, A. Chies-Santos, R. Riffel, F. L. Barbera, I. M. Navarro, J. Barroso, Tatiana Moura
Most of the observed galaxies cannot be resolved into individual stars and are studied through their integrated spectrum using simple stellar populations (SSPs) models, with stellar libraries being a key ingredient in building them. Spectroscopic observations are increasingly being directed towards the near-infrared (NIR), where much is yet to be explored. SSPs in the NIR are still limited, and there are inconsistencies between different sets of models. One of the ways to minimize this problem is to have reliable NIR stellar libraries. The main goal of this work is to present smarty (mileS Moderate resolution neAr-infRared sTellar librarY) a ∼0.9 − 2.4 μm stellar spectral library composed of 31 stars observed with the Gemini Near-IR Spectrograph (GNIRS) at the 8.1 m Gemini North telescope and make it available to the community. The stars were chosen from the miles library, for which the atmospheric parameters are reliable (and well tested), to populate different regions of the Hertzsprung-Russell (HR) diagram. Furthermore, five of these stars have NIR spectra available that we use to assess the quality of smarty. The remaining 26 stars are presented for the first time in the NIR. We compared the observed smarty spectra with synthetic and interpolated spectra, finding a mean difference of $sim 20%$ in the equivalent widths and ∼1% in the overall continuum shape in both sets of comparisons. We computed the spectrophotometric broadband magnitudes and colours and compared them with the 2MASS ones, resulting in mean differences up to 0.07 and 0.10 mag in magnitudes and colours, respectively. In general, a small difference was noted between the smarty spectra corrected using the continuum from the interpolated and the theoretical stars.
{"title":"SMARTY: The mileS Moderate resolution neAr-infRared sTellar librarY","authors":"Michele Bertoldo-Coelho, R. Riffel, Marina Trevisan, N. Dametto, L. Dahmer-Hahn, Paula Coelho, Lucimara P. Martins, D. Ruschel-Dutra, A. Vazdekis, Alberto Rodr'iguez-Ardila, A. Chies-Santos, R. Riffel, F. L. Barbera, I. M. Navarro, J. Barroso, Tatiana Moura","doi":"10.1093/mnras/stae1099","DOIUrl":"https://doi.org/10.1093/mnras/stae1099","url":null,"abstract":"\u0000 Most of the observed galaxies cannot be resolved into individual stars and are studied through their integrated spectrum using simple stellar populations (SSPs) models, with stellar libraries being a key ingredient in building them. Spectroscopic observations are increasingly being directed towards the near-infrared (NIR), where much is yet to be explored. SSPs in the NIR are still limited, and there are inconsistencies between different sets of models. One of the ways to minimize this problem is to have reliable NIR stellar libraries. The main goal of this work is to present smarty (mileS Moderate resolution neAr-infRared sTellar librarY) a ∼0.9 − 2.4 μm stellar spectral library composed of 31 stars observed with the Gemini Near-IR Spectrograph (GNIRS) at the 8.1 m Gemini North telescope and make it available to the community. The stars were chosen from the miles library, for which the atmospheric parameters are reliable (and well tested), to populate different regions of the Hertzsprung-Russell (HR) diagram. Furthermore, five of these stars have NIR spectra available that we use to assess the quality of smarty. The remaining 26 stars are presented for the first time in the NIR. We compared the observed smarty spectra with synthetic and interpolated spectra, finding a mean difference of $sim 20%$ in the equivalent widths and ∼1% in the overall continuum shape in both sets of comparisons. We computed the spectrophotometric broadband magnitudes and colours and compared them with the 2MASS ones, resulting in mean differences up to 0.07 and 0.10 mag in magnitudes and colours, respectively. In general, a small difference was noted between the smarty spectra corrected using the continuum from the interpolated and the theoretical stars.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"19 24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140673968","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}
Jennifer Y. H. Chan, Qin Han, K. Wu, Jason D. McEwen
The 21-cm hyperfine line of neutral hydrogen is a useful tool to probe the conditions of the Universe during the Dark Ages, Cosmic Dawn, and the Epoch of Reionisation. In most of the current calculations, the 21-cm line signals at given frequencies are computed, using an integrated line-of-sight line opacity, with the correction for cosmological expansion. These calculations have not fully captured the line and continuum interactions in the radiative transfer, in response to evolution of the radiation field and the variations of thermal and dynamic properties of the line-of-sight medium. We construct a covariant formulation for the radiative transfer of the 21-cm line and derive the cosmological 21-cm line radiative transfer (C21LRT) equation. The formulation properly accounts for local emission and absorption processes and the interaction between the line and continuum when the radiation propagates across the expanding Universe to the present observer. Our C21LRT calculations show that methods simply summing the line optical depth could lead to error of 5% in the 21-cm signals for redshift z ∼ 12 − 35 and of $>10~{{%}}$ for redshift z ≲ 8. Proper covariant radiative transfer is therefore necessary for producing correct theoretical templates for extracting information of the structural evolution of the Universe through the Epoch of Reionisation from the 21-cm tomographic data.
{"title":"A covariant formulation for cosmological radiative transfer of the 21-cm line","authors":"Jennifer Y. H. Chan, Qin Han, K. Wu, Jason D. McEwen","doi":"10.1093/mnras/stae1101","DOIUrl":"https://doi.org/10.1093/mnras/stae1101","url":null,"abstract":"\u0000 The 21-cm hyperfine line of neutral hydrogen is a useful tool to probe the conditions of the Universe during the Dark Ages, Cosmic Dawn, and the Epoch of Reionisation. In most of the current calculations, the 21-cm line signals at given frequencies are computed, using an integrated line-of-sight line opacity, with the correction for cosmological expansion. These calculations have not fully captured the line and continuum interactions in the radiative transfer, in response to evolution of the radiation field and the variations of thermal and dynamic properties of the line-of-sight medium. We construct a covariant formulation for the radiative transfer of the 21-cm line and derive the cosmological 21-cm line radiative transfer (C21LRT) equation. The formulation properly accounts for local emission and absorption processes and the interaction between the line and continuum when the radiation propagates across the expanding Universe to the present observer. Our C21LRT calculations show that methods simply summing the line optical depth could lead to error of 5% in the 21-cm signals for redshift z ∼ 12 − 35 and of $>10~{{%}}$ for redshift z ≲ 8. Proper covariant radiative transfer is therefore necessary for producing correct theoretical templates for extracting information of the structural evolution of the Universe through the Epoch of Reionisation from the 21-cm tomographic data.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"17 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674224","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}
To investigate the gas-phase hydrogenation processes of large, astronomically relevant cationic polycyclic aromatic hydrocarbon (PAH) molecules under the interstellar environments, the ion-molecule collision reaction between six PAH cations and H-atoms is studied. The experimental results show that the hydrogenated PAH cations are efficiently formed, and no even-odd hydrogenated mass patterns are observed in the hydrogenation processes. The structure of newly formed hydrogenated PAH cations and the bonding energy for the hydrogenation reaction pathways are investigated with quantum theoretical calculations. The exothermic energy for each reaction pathway is relatively high, and the competition between hydrogenation and dehydrogenation is confirmed. From the theoretical calculation, the bonding ability plays an important role in the gas-phase hydrogenation processes. The factors that affect the hydrogenation chemical reactivity are discussed, including the effect of carbon skeleton structure, the side-edged structure, the molecular size, the five- and six-membered C-ring structure, the bay region structure, and the neighboring hydrogenation. The IR spectra of hydrogenated PAH cations are also calculated. These results we obtain once again validate the complexity of hydrogenated PAH molecules, and provide the direction for the simulations and observations under the coevolution interstellar chemistry network. We infer that if we do not consider other chemical evolution processes (e.g., photo-evolution), then the hydrogenation states and forms of PAH compounds are intricate and complex in the interstellar medium (ISM).
为了研究在星际环境下与天文相关的大型阳离子多环芳烃（PAH）分子的气相氢化过程，研究了六种 PAH 阳离子与 H 原子之间的离子-分子碰撞反应。实验结果表明，氢化 PAH 阳离子是高效形成的，在氢化过程中没有观察到偶数氢化质量模式。量子理论计算研究了新形成的氢化 PAH 阳离子的结构和氢化反应途径的键能。各反应途径的放热能量相对较高，证实了氢化和脱氢之间的竞争关系。从理论计算结果来看，成键能力在气相加氢过程中起着重要作用。讨论了影响氢化化学反应活性的因素，包括碳骨架结构、侧边结构、分子大小、五元和六元 C 环结构、湾区结构以及邻近氢化的影响。同时还计算了氢化 PAH 阳离子的红外光谱。这些结果再次验证了氢化多环芳烃分子的复杂性，为星际化学网络协同演化下的模拟和观测提供了方向。我们推断，如果不考虑其他化学演化过程（如光演化），那么星际介质（ISM）中多环芳烃化合物的氢化状态和形式是错综复杂的。
{"title":"Gas-phase hydrogenation of large, astronomically relevant PAH cations","authors":"Lijun Hua, Xiaoyi Hu, Junfeng Zhen, Xuejuan Yang","doi":"10.1093/mnras/stae1082","DOIUrl":"https://doi.org/10.1093/mnras/stae1082","url":null,"abstract":"\u0000 To investigate the gas-phase hydrogenation processes of large, astronomically relevant cationic polycyclic aromatic hydrocarbon (PAH) molecules under the interstellar environments, the ion-molecule collision reaction between six PAH cations and H-atoms is studied. The experimental results show that the hydrogenated PAH cations are efficiently formed, and no even-odd hydrogenated mass patterns are observed in the hydrogenation processes. The structure of newly formed hydrogenated PAH cations and the bonding energy for the hydrogenation reaction pathways are investigated with quantum theoretical calculations. The exothermic energy for each reaction pathway is relatively high, and the competition between hydrogenation and dehydrogenation is confirmed. From the theoretical calculation, the bonding ability plays an important role in the gas-phase hydrogenation processes. The factors that affect the hydrogenation chemical reactivity are discussed, including the effect of carbon skeleton structure, the side-edged structure, the molecular size, the five- and six-membered C-ring structure, the bay region structure, and the neighboring hydrogenation. The IR spectra of hydrogenated PAH cations are also calculated. These results we obtain once again validate the complexity of hydrogenated PAH molecules, and provide the direction for the simulations and observations under the coevolution interstellar chemistry network. We infer that if we do not consider other chemical evolution processes (e.g., photo-evolution), then the hydrogenation states and forms of PAH compounds are intricate and complex in the interstellar medium (ISM).","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"85 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140676967","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}
M. B. Planes, M. G. Parisi, E. N. Millán, E. Bringa, Marcela Cañada-Assandri
Silica has emerged as a crucial component within inner comet comas. This work investigates silica dust aggregates and their interactions within cometary comas. We study the probability that aggregates in the size range 1-100 μm collide with each other in the coma and analyze the outcomes of such collisions by using the “Collision of Porous Aggregates” (CPA) Software, which incorporates mass, size, and porosity evolution of the dust population. Beginning with assumed initial distributions and physical properties for silica aggregates at the comet nucleus, we compute their collisional evolution from when they depart the nucleus until they traverse the coma. Using data of dust particles observed in the coma of comet 67P/Churyumov-Gerasimenko, we demonstrate that dust-dust collisions in cometary comas cannot be neglected. Our analysis yields final distributions in terms of mass, size, and porosity. To validate our findings, we compare them with in-situ measurements of 67P/Churyumov-Gerasimenko collected by the COSIMA (COmetary Secondary Ion Mass Analyser) instrument of the Rosetta mission. Our investigation reveals a notable agreement between our derived size distributions and the data acquired by COSIMA within the same size range. This study may be applied to any comet that presents a similar dust production as it approaches the Sun. The insights of this work may contribute to estimating other dust properties such as strength, absorption, reflectivity, and thermal conductivity and highlight the importance of considering dust-dust collisions when studying cometary comas and their evolution.
{"title":"Dust-dust collisions in cometary comas: applications to comet 67P/Churyumov-Gerasimenko","authors":"M. B. Planes, M. G. Parisi, E. N. Millán, E. Bringa, Marcela Cañada-Assandri","doi":"10.1093/mnras/stae1078","DOIUrl":"https://doi.org/10.1093/mnras/stae1078","url":null,"abstract":"\u0000 Silica has emerged as a crucial component within inner comet comas. This work investigates silica dust aggregates and their interactions within cometary comas. We study the probability that aggregates in the size range 1-100 μm collide with each other in the coma and analyze the outcomes of such collisions by using the “Collision of Porous Aggregates” (CPA) Software, which incorporates mass, size, and porosity evolution of the dust population. Beginning with assumed initial distributions and physical properties for silica aggregates at the comet nucleus, we compute their collisional evolution from when they depart the nucleus until they traverse the coma. Using data of dust particles observed in the coma of comet 67P/Churyumov-Gerasimenko, we demonstrate that dust-dust collisions in cometary comas cannot be neglected. Our analysis yields final distributions in terms of mass, size, and porosity. To validate our findings, we compare them with in-situ measurements of 67P/Churyumov-Gerasimenko collected by the COSIMA (COmetary Secondary Ion Mass Analyser) instrument of the Rosetta mission. Our investigation reveals a notable agreement between our derived size distributions and the data acquired by COSIMA within the same size range. This study may be applied to any comet that presents a similar dust production as it approaches the Sun. The insights of this work may contribute to estimating other dust properties such as strength, absorption, reflectivity, and thermal conductivity and highlight the importance of considering dust-dust collisions when studying cometary comas and their evolution.","PeriodicalId":506975,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"82 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140677117","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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