Pub Date : 2024-07-16DOI: 10.1051/0004-6361/202450087
D. Fasano, A. J. Winter, M. Benisty, G. Rosotti, A. Ruzza, G. Lodato, C. Toci, T. Hilder, A. Izquierdo, D. Price
Context. Detecting protoplanets during their formation stage is an important but elusive goal of modern astronomy. Kinematic detections via the spiral wakes in the gaseous disc are a promising avenue to achieve this goal.Aims. We aim to test the applicability of a commonly used semi-analytical model for planet-induced spiral waves to observations in the low and intermediate planet mass regimes. In contrast to previous works that proposed using the semi-analytical model to interpret observations, in this study we analyse for the first time both the structure of the velocity and density perturbations. Methods. We ran a set of FARGO3D hydrodynamic simulations and compared them with the output of the semi-analytic model in the code WAKEFLOW. We divided the disc into two regions. We used the density and velocity fields from the simulation in the linear region, where density waves are excited. In the non-linear region, where density waves propagate through the disc, we then solved Burgers’ equation to obtain the density field, from which we computed the velocity field.Results. We find that the velocity field derived from the analytic theory is discontinuous at the interface between the linear and nonlinear regions. After ~0.2 rp from the planet, the behaviour of the velocity field closely follows that of the density perturbations. In the low mass limit, the analytical model is in qualitative agreement with the simulations, although it underestimates the azimuthal width and the amplitude of the perturbations, predicting a stronger decay but a slower azimuthal advance of the shock fronts. In the intermediate regime, the discrepancy increases, resulting in a different pitch angle between the spirals of the simulations and the analytic model.Conclusions. The implementation of a fitting procedure based on the minimisation of intensity residuals is bound to fail due to the deviation in pitch angle between the analytic model and the simulations. In order to apply this model to observations, it needs to be revisited so that it can also account for higher planet masses.
背景。探测处于形成阶段的原行星是现代天文学的一个重要但难以实现的目标。通过气态圆盘中的螺旋波进行运动学探测是实现这一目标的一个很有希望的途径。我们的目的是测试行星诱发螺旋波的常用半分析模型对中低行星质量观测的适用性。与之前提出使用半解析模型来解释观测结果的工作不同，在这项研究中，我们首次分析了速度和密度扰动的结构。研究方法我们运行了一组 FARGO3D 流体动力模拟，并与 WAKEFLOW 代码中半解析模型的输出结果进行了比较。我们将圆盘分为两个区域。在密度波被激发的线性区域，我们使用了模拟得到的密度场和速度场。在密度波在圆盘中传播的非线性区域，我们求解了布尔格斯方程，得到了密度场，并据此计算出了速度场。我们发现，从解析理论得出的速度场在线性区和非线性区的交界处是不连续的。在距离行星约 0.2 rp 之后，速度场的行为与密度扰动密切相关。在低质量极限，尽管分析模型低估了扰动的方位角宽度和振幅，预测了冲击前沿较强的衰减但较慢的方位角前进速度，但分析模型与模拟结果在质量上是一致的。在中间阶段，差异增大，导致模拟和分析模型的螺旋俯仰角不同。由于分析模型与模拟结果的俯仰角存在偏差，基于强度残差最小化的拟合程序必然会失败。为了将这一模型应用于观测，需要对其进行重新审视，使其也能考虑到更高的行星质量。
{"title":"Planet-driven spirals in protoplanetary discs: Limitations of the semi-analytical theory for observations","authors":"D. Fasano, A. J. Winter, M. Benisty, G. Rosotti, A. Ruzza, G. Lodato, C. Toci, T. Hilder, A. Izquierdo, D. Price","doi":"10.1051/0004-6361/202450087","DOIUrl":"https://doi.org/10.1051/0004-6361/202450087","url":null,"abstract":"<i>Context.<i/> Detecting protoplanets during their formation stage is an important but elusive goal of modern astronomy. Kinematic detections via the spiral wakes in the gaseous disc are a promising avenue to achieve this goal.<i>Aims.<i/> We aim to test the applicability of a commonly used semi-analytical model for planet-induced spiral waves to observations in the low and intermediate planet mass regimes. In contrast to previous works that proposed using the semi-analytical model to interpret observations, in this study we analyse for the first time both the structure of the velocity and density perturbations. <i>Methods.<i/> We ran a set of FARGO3D hydrodynamic simulations and compared them with the output of the semi-analytic model in the code WAKEFLOW. We divided the disc into two regions. We used the density and velocity fields from the simulation in the linear region, where density waves are excited. In the non-linear region, where density waves propagate through the disc, we then solved Burgers’ equation to obtain the density field, from which we computed the velocity field.<i>Results.<i/> We find that the velocity field derived from the analytic theory is discontinuous at the interface between the linear and nonlinear regions. After ~0.2 <i>r<i/><sub>p<sub/> from the planet, the behaviour of the velocity field closely follows that of the density perturbations. In the low mass limit, the analytical model is in qualitative agreement with the simulations, although it underestimates the azimuthal width and the amplitude of the perturbations, predicting a stronger decay but a slower azimuthal advance of the shock fronts. In the intermediate regime, the discrepancy increases, resulting in a different pitch angle between the spirals of the simulations and the analytic model.<i>Conclusions.<i/> The implementation of a fitting procedure based on the minimisation of intensity residuals is bound to fail due to the deviation in pitch angle between the analytic model and the simulations. In order to apply this model to observations, it needs to be revisited so that it can also account for higher planet masses.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.1051/0004-6361/202450141
P. Berczik, M. Sobolenko, M. Ishchenko
Aims. Based on the available observational data from the literature, we analysed the dynamics of the NGC 6240 galaxy central supermassive black hole (SMBH) system.Methods. For the dynamical modelling of this triple SBMH system, we used the massively parallel and GPU accelerated φ-GPU direct summation N-body code. Following a long-timescale modelling of the triple system, we carried out a very detailed time output analysis of the von Zeipel–Lidov–Kozai (ZLK) oscillations for the black holes.Results. According to our Newtonian simulation results, for all models and randomisations, the bound system from S1+S2 components formed at ≈3.6 Myr. The formation of the bound hierarchical triple system S+N occurred at ≈18 Myr. Over the course of these Newtonian simulations of the evolution of the triple SMBH system and the surrounding environment in NGC 6240, ZLK oscillations were detected (in most cases) for the binary components. The inclination angle between the orbital angular momentum of binary components aptly coincides with the theoretical calculations of the ZLK mechanism.Conclusions. In our set of randomised 15 Newtonian N-body dynamical galaxy models in 13 systems, we were able to detect a ZLK mechanism. In contrast, our extra few-body post-Newtonian runs (for one randomisation case) show it is only for the large inner binary initial eccentricity (in our case ≳0.9) that we are able to observe the possibility of the inner binary merging, due to the post-Newtonian energy radiation effects. For the lower eccentricity cases, the test runs show no sign of possible merging or any ZLK oscillations in the system.
{"title":"Dynamical evolution timescales for the triple supermassive black hole system in NGC 6240","authors":"P. Berczik, M. Sobolenko, M. Ishchenko","doi":"10.1051/0004-6361/202450141","DOIUrl":"https://doi.org/10.1051/0004-6361/202450141","url":null,"abstract":"<i>Aims.<i/> Based on the available observational data from the literature, we analysed the dynamics of the NGC 6240 galaxy central supermassive black hole (SMBH) system.<i>Methods.<i/> For the dynamical modelling of this triple SBMH system, we used the massively parallel and GPU accelerated <i>φ<i/>-GPU direct summation <i>N<i/>-body code. Following a long-timescale modelling of the triple system, we carried out a very detailed time output analysis of the von Zeipel–Lidov–Kozai (ZLK) oscillations for the black holes.<i>Results.<i/> According to our Newtonian simulation results, for all models and randomisations, the bound system from S1+S2 components formed at ≈3.6 Myr. The formation of the bound hierarchical triple system S+N occurred at ≈18 Myr. Over the course of these Newtonian simulations of the evolution of the triple SMBH system and the surrounding environment in NGC 6240, ZLK oscillations were detected (in most cases) for the binary components. The inclination angle between the orbital angular momentum of binary components aptly coincides with the theoretical calculations of the ZLK mechanism.<i>Conclusions.<i/> In our set of randomised 15 Newtonian <i>N<i/>-body dynamical galaxy models in 13 systems, we were able to detect a ZLK mechanism. In contrast, our extra few-body post-Newtonian runs (for one randomisation case) show it is only for the large inner binary initial eccentricity (in our case ≳0.9) that we are able to observe the possibility of the inner binary merging, due to the post-Newtonian energy radiation effects. For the lower eccentricity cases, the test runs show no sign of possible merging or any ZLK oscillations in the system.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.1051/0004-6361/202450405
N. F. W. Ligterink, K. A. Kipfer, S. Gavino
Aims. The ability of bulk ices (H2O, CO2) to trap volatiles has been well studied in any experimental sense, but largely ignored in protoplanetary disk and planet formation models as well as the interpretation of their observations. We demonstrate the influence of volatile trapping on C/O ratios in planet-forming environments.Methods. We created a simple model of CO, CO2, and H2O snowlines in protoplanetary disks and calculated the C/O ratio at different radii and temperatures. We included a trapping factor, which partially inhibits the release of volatiles (CO, CO2) at their snowline and releases them instead, together with the bulk ice species (H2O, CO2). Our aim has been to assess its influence of trapping solid-state and gas phase C/O ratios throughout planet-forming environments.Results. Volatile trapping significantly affects C/O ratios in protoplanetary disks. Variations in the ratio are reduced and become more homogeneous throughout the disk when compared to models that do not include volatile trapping. Trapping reduces the proportion of volatiles in the gas and, as such, reduces the available carbon- and oxygen-bearing molecules for gaseous accretion to planetary atmospheres. Volatile trapping is expected to also affect the elemental hydrogen and nitrogen budgets.Conclusions. Volatile trapping is an overlooked, but important effect to consider when assessing the C/O ratios in protoplanetary disks and exoplanet atmospheres. Due to volatile trapping, exoplanets with stellar C/O have the possibility to be formed within the CO and CO2 snowline.
{"title":"Mind the trap","authors":"N. F. W. Ligterink, K. A. Kipfer, S. Gavino","doi":"10.1051/0004-6361/202450405","DOIUrl":"https://doi.org/10.1051/0004-6361/202450405","url":null,"abstract":"<i>Aims.<i/> The ability of bulk ices (H<sub>2<sub/>O, CO<sub>2<sub/>) to trap volatiles has been well studied in any experimental sense, but largely ignored in protoplanetary disk and planet formation models as well as the interpretation of their observations. We demonstrate the influence of volatile trapping on C/O ratios in planet-forming environments.<i>Methods.<i/> We created a simple model of CO, CO<sub>2<sub/>, and H<sub>2<sub/>O snowlines in protoplanetary disks and calculated the C/O ratio at different radii and temperatures. We included a trapping factor, which partially inhibits the release of volatiles (CO, CO<sub>2<sub/>) at their snowline and releases them instead, together with the bulk ice species (H<sub>2<sub/>O, CO<sub>2<sub/>). Our aim has been to assess its influence of trapping solid-state and gas phase C/O ratios throughout planet-forming environments.<i>Results.<i/> Volatile trapping significantly affects C/O ratios in protoplanetary disks. Variations in the ratio are reduced and become more homogeneous throughout the disk when compared to models that do not include volatile trapping. Trapping reduces the proportion of volatiles in the gas and, as such, reduces the available carbon- and oxygen-bearing molecules for gaseous accretion to planetary atmospheres. Volatile trapping is expected to also affect the elemental hydrogen and nitrogen budgets.<i>Conclusions.<i/> Volatile trapping is an overlooked, but important effect to consider when assessing the C/O ratios in protoplanetary disks and exoplanet atmospheres. Due to volatile trapping, exoplanets with stellar C/O have the possibility to be formed within the CO and CO<sub>2<sub/> snowline.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.1051/0004-6361/202450221
Cheongho Han, Ian A. Bond, Chung-Uk Lee, Andrew Gould, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, Yossi Shvartzvald, In-Gu Shin, Jennifer C. Yee, Hongjing Yang, Weicheng Zang, Sang-Mok Cha, Doeon Kim, Dong-Jin Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Fumio Abe, Ken Bando, Richard Barry, David P. Bennett, Aparna Bhattacharya, Hirosame Fujii, Akihiko Fukui, Ryusei Hamada, Shunya Hamada, Naoto Hamasaki, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Naoki Koshimoto, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Takahiro Sumi, Daisuke Suzuki, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Kansuke Yamashita, Etienne Bachelet, Paolo Rota, Valerio Bozza, Paweł Zielinski, Rachel A. Street, Yiannis Tsapras, Markus Hundertmark, Joachim Wambsganss, Łukasz Wyrzykowski, Roberto Figuera Jaimes, Arnaud Cassan, Martin Dominik, Krzysztof A. Rybicki, Markus Rabus
Aims. We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followed by subsequent troughs that extend across a substantial portion of the light curves.Methods. We performed thorough modeling of the anomalies to elucidate their characteristics. Despite their prolonged durations, which differ from the usual brief anomalies observed in typical planetary events, our analysis revealed that each anomaly in these events originated from a planetary companion located within the Einstein ring of the primary star. It was found that the initial bump arouse when the source star crossed one of the planetary caustics, while the subsequent trough feature occurred as the source traversed the region of minor image perturbations lying between the pair of planetary caustics.Results. The estimated masses of the host and planet, their mass ratios, and the distance to the discovered planetary systems are (Mhost/M⊙, Mplanet/MJ, q/10−3, DL/kpc) = (0.58−0.30+0.33, 10.71−5.61+6.17, 17.61 ± 2.25, 6.67−1.30+0.93) for KMT-2020-BLG-0757, (0.53−0.31+0.31, 1.12−0.65+0.65, 2.01 ± 0.07, 6.66−1.84+1.19) for KMT-2022-BLG-0732, (0.42−0.23+0.32, 6.64−3.64+4.98, 15.07 ± 0.86, 7.55−1.30+0.89) for KMT-2022-BLG-1787, and (0.32−0.19+0.34, 4.98−2.94+5.42, 8.74 ± 0.49, 6.27−1.15+0.90) for KMT-2022-BLG-1852. These parameters indicate that all the planets are giants with masses exceeding the mass of Jupiter in our solar system and the hosts are low-mass stars with masses substantially less massive than the Sun.
{"title":"Four microlensing giant planets detected through signals produced by minor-image perturbations","authors":"Cheongho Han, Ian A. Bond, Chung-Uk Lee, Andrew Gould, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, Yossi Shvartzvald, In-Gu Shin, Jennifer C. Yee, Hongjing Yang, Weicheng Zang, Sang-Mok Cha, Doeon Kim, Dong-Jin Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Fumio Abe, Ken Bando, Richard Barry, David P. Bennett, Aparna Bhattacharya, Hirosame Fujii, Akihiko Fukui, Ryusei Hamada, Shunya Hamada, Naoto Hamasaki, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Naoki Koshimoto, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Takahiro Sumi, Daisuke Suzuki, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Kansuke Yamashita, Etienne Bachelet, Paolo Rota, Valerio Bozza, Paweł Zielinski, Rachel A. Street, Yiannis Tsapras, Markus Hundertmark, Joachim Wambsganss, Łukasz Wyrzykowski, Roberto Figuera Jaimes, Arnaud Cassan, Martin Dominik, Krzysztof A. Rybicki, Markus Rabus","doi":"10.1051/0004-6361/202450221","DOIUrl":"https://doi.org/10.1051/0004-6361/202450221","url":null,"abstract":"<i>Aims.<i/> We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followed by subsequent troughs that extend across a substantial portion of the light curves.<i>Methods.<i/> We performed thorough modeling of the anomalies to elucidate their characteristics. Despite their prolonged durations, which differ from the usual brief anomalies observed in typical planetary events, our analysis revealed that each anomaly in these events originated from a planetary companion located within the Einstein ring of the primary star. It was found that the initial bump arouse when the source star crossed one of the planetary caustics, while the subsequent trough feature occurred as the source traversed the region of minor image perturbations lying between the pair of planetary caustics.<i>Results.<i/> The estimated masses of the host and planet, their mass ratios, and the distance to the discovered planetary systems are (<i>M<i/><sub>host<sub/>/<i>M<i/><sub>⊙<sub/>, <i>M<i/><sub>planet<sub/><i>/M<i/><sub>J<sub/>, <i>q<i/>/10<sup>−3<sup/>, <i>D<i/><sub>L<sub/>/kpc) = (0.58<sub>−0.30<sub/><sup>+0.33<sup/>, 10.71<sub>−5.61<sub/><sup>+6.17<sup/>, 17.61 ± 2.25, 6.67<sub>−1.30<sub/><sup>+0.93<sup/>) for KMT-2020-BLG-0757, (0.53<sub>−0.31<sub/><sup>+0.31<sup/>, 1.12<sub>−0.65<sub/><sup>+0.65<sup/>, 2.01 ± 0.07, 6.66<sub>−1.84<sub/><sup>+1.19<sup/>) for KMT-2022-BLG-0732, (0.42<sub>−0.23<sub/><sup>+0.32<sup/>, 6.64<sub>−3.64<sub/><sup>+4.98<sup/>, 15.07 ± 0.86, 7.55<sub>−1.30<sub/><sup>+0.89<sup/>) for KMT-2022-BLG-1787, and (0.32<sub>−0.19<sub/><sup>+0.34<sup/>, 4.98<sub>−2.94<sub/><sup>+5.42<sup/>, 8.74 ± 0.49, 6.27<sub>−1.15<sub/><sup>+0.90<sup/>) for KMT-2022-BLG-1852. These parameters indicate that all the planets are giants with masses exceeding the mass of Jupiter in our solar system and the hosts are low-mass stars with masses substantially less massive than the Sun.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1051/0004-6361/202450688
Hui-Fang Xue, Jia-Shu Niu
Harmonics are a ubiquitous feature across various pulsating stars. They are traditionally viewed as mere replicas of the independent primary pulsation modes and have thus been excluded from asteroseismological models. Recent research, however, has uncovered a significant discrepancy: in high-amplitude δ Scuti (HADS) stars, harmonics exhibit uncorrelated variations in amplitude and frequency relative to their independent primary pulsation modes. The nature of these disharmonized harmonics is a question of critical importance. In our study we analysed five triple-mode HADS stars observed by the Transiting Exoplanet Survey Satellite (TESS) and discovered some pervasive patterns of disharmonized harmonics in both the fundamental (f0) and first overtone (f1) pulsation modes. Intriguingly, through an in-depth frequency interaction analysis of V1393 Cen, we identified 2f1 as an independent pulsation mode, distinct from f1, and identified it as the progenitor of the frequency variations observed in 3f1, 4f1, 5f1, and 6f1. Similar behaviour can be found in DO CMi and GSC 06047-00749, in which 2f1 and 3f1 are the independent pulsation modes, respectively. Notably, we found an interesting pattern when decomposing the harmonics that might suggest a generation process of harmonics. These findings serve as a new window on the research of harmonics, which remains a hidden corner of contemporary asteroseismology.
{"title":"Exploring the unexpected: Disharmonized harmonic pulsation modes in high-amplitude δ Scuti stars","authors":"Hui-Fang Xue, Jia-Shu Niu","doi":"10.1051/0004-6361/202450688","DOIUrl":"https://doi.org/10.1051/0004-6361/202450688","url":null,"abstract":"Harmonics are a ubiquitous feature across various pulsating stars. They are traditionally viewed as mere replicas of the independent primary pulsation modes and have thus been excluded from asteroseismological models. Recent research, however, has uncovered a significant discrepancy: in high-amplitude <i>δ<i/> Scuti (HADS) stars, harmonics exhibit uncorrelated variations in amplitude and frequency relative to their independent primary pulsation modes. The nature of these disharmonized harmonics is a question of critical importance. In our study we analysed five triple-mode HADS stars observed by the Transiting Exoplanet Survey Satellite (TESS) and discovered some pervasive patterns of disharmonized harmonics in both the fundamental (<i>f<i/><sub>0<sub/>) and first overtone (<i>f<i/><sub>1<sub/>) pulsation modes. Intriguingly, through an in-depth frequency interaction analysis of V1393 Cen, we identified 2<i>f<i/><sub>1<sub/> as an independent pulsation mode, distinct from <i>f<i/><sub>1<sub/>, and identified it as the progenitor of the frequency variations observed in 3<i>f<i/><sub>1<sub/>, 4<i>f<i/><sub>1<sub/>, 5<i>f<i/><sub>1<sub/>, and 6<i>f<i/><sub>1<sub/>. Similar behaviour can be found in DO CMi and GSC 06047-00749, in which 2<i>f<i/><sub>1<sub/> and 3<i>f<i/><sub>1<sub/> are the independent pulsation modes, respectively. Notably, we found an interesting pattern when decomposing the harmonics that might suggest a generation process of harmonics. These findings serve as a new window on the research of harmonics, which remains a hidden corner of contemporary asteroseismology.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141618309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Observations of nearby massive galaxies have revealed that they are older and richer in metals and magnesium than their low-mass counterparts. In particular, the overabundance of magnesium compared to iron, [Mg/Fe], is interpreted to reflect the short star formation history that the current massive galaxies underwent early in the Universe. We present a systematic revision of the [Mg/Fe] – velocity dispersion (σ) relation based on stacked spectra of early-type galaxies with a high signal-to-noise ratio from the Sloan Digital Sky Survey. Using the penalized pixel-fitting (pPXF) method and the MILES single stellar population models, we fit a wide optical wavelength range to measure the net α-abundance. The combination of pPXF and α-enhanced MILES models incorrectly leads to an apparently decreasing trend of [α/Fe] with velocity dispersion. We interpret this result as a consequence of variations in the individual abundances of the different α-elements. This warrants caution for a naive use of full spectral fitting algorithms paired with stellar population models that do not take individual elemental abundance variations into account, especially when deriving averaged quantities such as the mean [α/Fe] of a stellar population. In addition, and based on line-strength measurements, we quantify the impact of a non-universal initial mass function on the recovered abundance pattern of galaxies. In particular, we find that a simultaneous fit of the slope of the initial mass function and the [Mg/Fe] results in a shallower [Mg/Fe]–σ relation. Therefore, our results suggest that star formation in massive galaxies lasted longer than what has been reported previously, although it still occurred significantly faster than in the solar neighbourhood.
对附近大质量星系的观测表明，它们比低质量的同类星系更古老，金属和镁的含量也更丰富。尤其是镁含量（[Mg/Fe]）比铁含量（[Mg/Fe]）高，这被解释为反映了当前大质量星系在宇宙早期所经历的短暂恒星形成历史。我们基于斯隆数字巡天中高信噪比的早期型星系的叠加光谱，对[Mg/Fe]-速度色散（σ）关系进行了系统的修正。利用惩罚性像素拟合（pPXF）方法和 MILES 单恒星群模型，我们拟合了很宽的光学波长范围，测量了净α丰度。pPXF 和 α 增强 MILES 模型的组合错误地导致了[α/Fe]随速度色散明显下降的趋势。我们将这一结果解释为不同α元素个体丰度变化的结果。这就要求我们在使用全光谱拟合算法和恒星群模型时，尤其是在推导恒星群的平均[α/Fe]等平均量时，一定要谨慎。此外，根据线强度测量结果，我们量化了非通用初始质量函数对恢复的星系丰度模式的影响。特别是，我们发现同时拟合初始质量函数斜率和[Mg/Fe]会导致较浅的[Mg/Fe]-σ关系。因此，我们的研究结果表明，大质量星系中恒星形成的时间比以前报道的要长，尽管它的形成速度仍然明显快于太阳附近的星系。
{"title":"[Mg/Fe] and variable initial mass function: Revision of [α/Fe] for massive galaxies","authors":"Emilie Pernet, Alina Boecker, Ignacio Martín-Navarro","doi":"10.1051/0004-6361/202449308","DOIUrl":"https://doi.org/10.1051/0004-6361/202449308","url":null,"abstract":"Observations of nearby massive galaxies have revealed that they are older and richer in metals and magnesium than their low-mass counterparts. In particular, the overabundance of magnesium compared to iron, [Mg/Fe], is interpreted to reflect the short star formation history that the current massive galaxies underwent early in the Universe. We present a systematic revision of the [Mg/Fe] – velocity dispersion (<i>σ<i/>) relation based on stacked spectra of early-type galaxies with a high signal-to-noise ratio from the Sloan Digital Sky Survey. Using the penalized pixel-fitting (pPXF) method and the MILES single stellar population models, we fit a wide optical wavelength range to measure the net <i>α<i/>-abundance. The combination of pPXF and <i>α<i/>-enhanced MILES models incorrectly leads to an apparently decreasing trend of [<i>α<i/>/Fe] with velocity dispersion. We interpret this result as a consequence of variations in the individual abundances of the different <i>α<i/>-elements. This warrants caution for a naive use of full spectral fitting algorithms paired with stellar population models that do not take individual elemental abundance variations into account, especially when deriving averaged quantities such as the mean [<i>α<i/>/Fe] of a stellar population. In addition, and based on line-strength measurements, we quantify the impact of a non-universal initial mass function on the recovered abundance pattern of galaxies. In particular, we find that a simultaneous fit of the slope of the initial mass function and the [Mg/Fe] results in a shallower [Mg/Fe]–<i>σ<i/> relation. Therefore, our results suggest that star formation in massive galaxies lasted longer than what has been reported previously, although it still occurred significantly faster than in the solar neighbourhood.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141618371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1051/0004-6361/202450538
Jérôme Pétri, Sebastien Guillot, Lucas Guillemot, Dipanjan Mitra, Matthew Kerr, Lucien Kuiper, Ismaël Cognard, Gilles Theureau
Context. Pulsars are detected over the whole electromagnetic spectrum, from radio wavelengths up to very high energies, in the GeV-TeV range. While the radio emission site for young pulsars is well constrained to occur at altitudes about several percent of the light-cylinder radius and γ-ray emission is believed to be produced in the striped wind, outside the light cylinder, the non-thermal X-ray production site remains unknown.Aims. The aim of this Letter is to localize the non-thermal X-ray emission region based on a multi-wavelength pulse profile fitting for PSR J2229+6114, which stands as a particularly good candidate given its high X-ray brightness.Methods. Based on the geometry deduced from the joint radio and γ-ray pulse profiles, we fixed the magnetic axis inclination angle and the line-of-sight (LoS) inclination angle. However, we left the region of X-ray emission unlocalized, setting it somewhere between the surface and the light cylinder. We localized this region and its extension by fitting the X-ray pulse profile as observed by the NICER, NuSTAR, and RXTE telescopes in the ranges of 2–7 keV, 3–10 keV, and 9.4–22.4 keV, respectively.Results. We constrained the non-thermal X-ray emission to arise from altitudes between 0.2 rL and 0.55 rL where rL is the light-cylinder radius. The magnetic obliquity is approximately α ≈ 45° −50° and the LoS inclination angle is ζ ≈ 32° −48°.Conclusions. This Letter is among the first works to offer a tight constraint on the location of non-thermal X-ray emission from pulsars. We plan to apply this procedure to several other promising candidates to confirm this new result.
背景。脉冲星在整个电磁波谱范围内都能被探测到，从射电波长直到 GeV-TeV 范围内的极高能量。虽然年轻脉冲星的射电发射地点被精确地确定在光柱半径的百分之几高度，γ射线发射被认为是在光柱外的条纹风中产生的，但非热辐射 X 射线的产生地点仍然未知。这封信的目的是基于对PSR J2229+6114的多波长脉冲轮廓拟合来定位非热X射线发射区域，鉴于其较高的X射线亮度，PSR J2229+6114是一个特别好的候选者。根据联合射电和γ射线脉冲剖面推断出的几何形状，我们固定了磁轴倾角和视线倾角。但是，我们没有定位 X 射线发射区域，而是将其定位于表面和光柱之间的某处。我们通过拟合 NICER、NuSTAR 和 RXTE 望远镜分别在 2-7keV、3-10 keV 和 9.4-22.4 keV 范围内观测到的 X 射线脉冲轮廓，确定了这一区域及其延伸部分。我们确定非热 X 射线辐射来自 0.2 rL 和 0.55 rL 之间的高度，其中 rL 是光柱半径。磁偏角约为α ≈ 45° -50°，LoS倾角为ζ ≈ 32° -48°。这封信是第一批对脉冲星非热X射线发射位置提供严格约束的作品之一。我们计划将这一程序应用于其他几个有希望的候选者，以证实这一新结果。
{"title":"Localizing the non-thermal X-ray emission of PSR J2229+6114 from its multi-wavelength pulse profiles","authors":"Jérôme Pétri, Sebastien Guillot, Lucas Guillemot, Dipanjan Mitra, Matthew Kerr, Lucien Kuiper, Ismaël Cognard, Gilles Theureau","doi":"10.1051/0004-6361/202450538","DOIUrl":"https://doi.org/10.1051/0004-6361/202450538","url":null,"abstract":"<i>Context.<i/> Pulsars are detected over the whole electromagnetic spectrum, from radio wavelengths up to very high energies, in the GeV-TeV range. While the radio emission site for young pulsars is well constrained to occur at altitudes about several percent of the light-cylinder radius and <i>γ<i/>-ray emission is believed to be produced in the striped wind, outside the light cylinder, the non-thermal X-ray production site remains unknown.<i>Aims.<i/> The aim of this Letter is to localize the non-thermal X-ray emission region based on a multi-wavelength pulse profile fitting for PSR J2229+6114, which stands as a particularly good candidate given its high X-ray brightness.<i>Methods.<i/> Based on the geometry deduced from the joint radio and <i>γ<i/>-ray pulse profiles, we fixed the magnetic axis inclination angle and the line-of-sight (LoS) inclination angle. However, we left the region of X-ray emission unlocalized, setting it somewhere between the surface and the light cylinder. We localized this region and its extension by fitting the X-ray pulse profile as observed by the NICER, <i>NuSTAR<i/>, and RXTE telescopes in the ranges of 2–7 keV, 3–10 keV, and 9.4–22.4 keV, respectively.<i>Results.<i/> We constrained the non-thermal X-ray emission to arise from altitudes between 0.2 <i>r<i/><sub>L<sub/> and 0.55 <i>r<i/><sub>L<sub/> where <i>r<i/><sub>L<sub/> is the light-cylinder radius. The magnetic obliquity is approximately <i>α<i/> ≈ 45° −50° and the LoS inclination angle is <i>ζ<i/> ≈ 32° −48°.<i>Conclusions.<i/> This Letter is among the first works to offer a tight constraint on the location of non-thermal X-ray emission from pulsars. We plan to apply this procedure to several other promising candidates to confirm this new result.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141618302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1051/0004-6361/202450191
T. Nagao, K. Maeda, S. Mattila, H. Kuncarayakti, M. Kawabata, K. Taguchi, T. Nakaoka, A. Cikota, M. Bulla, S. S. Vasylyev, C. P. Gutiérrez, M. Yamanaka, K. Isogai, K. Uno, M. Ogawa, S. Inutsuka, M. Tsurumi, R. Imazawa, K. S. Kawabata
Aims. Recent observations of core-collapse supernovae (SNe) suggest aspherical explosions. Globally, aspherical structures in SN explosions are thought to encode information regarding the underlying explosion mechanism. However, the exact explosion geometries from the inner cores to the outer envelopes are poorly understood.Methods. Here, we present photometric, spectroscopic, and polarimetric observations of the Type IIP SN 2021yja and discuss its explosion geometry in comparison to those of other Type IIP SNe that show large-scale aspherical structures in their hydrogen envelopes (SNe 2012aw, 2013ej and 2017gmr).Results. During the plateau phase, SNe 2012aw and 2021yja exhibit high continuum polarization characterized by two components with perpendicular polarization angles. This behavior can be interpreted as being due to a bipolar explosion, where the SN ejecta is composed of a polar (energetic) component and an equatorial (bulk) component. In such a bipolar explosion, an aspherical axis created by the polar ejecta would dominate at early phases, while the perpendicular axis along the equatorial ejecta would emerge at late phases after the photosphere in the polar ejecta has receded. Our interpretation of the explosions in SNe 2012aw and 2021yja as bipolar is also supported by other observational properties, including the time evolution of the line velocities and the line shapes in the nebular spectra. The polarization of other Type IIP SNe that show large-scale aspherical structures in the hydrogen envelope (SNe 2013ej and 2017gmr) is also consistent with the bipolar-explosion scenario, although this is not conclusive.
{"title":"Evidence for bipolar explosions in Type IIP supernovae","authors":"T. Nagao, K. Maeda, S. Mattila, H. Kuncarayakti, M. Kawabata, K. Taguchi, T. Nakaoka, A. Cikota, M. Bulla, S. S. Vasylyev, C. P. Gutiérrez, M. Yamanaka, K. Isogai, K. Uno, M. Ogawa, S. Inutsuka, M. Tsurumi, R. Imazawa, K. S. Kawabata","doi":"10.1051/0004-6361/202450191","DOIUrl":"https://doi.org/10.1051/0004-6361/202450191","url":null,"abstract":"<i>Aims.<i/> Recent observations of core-collapse supernovae (SNe) suggest aspherical explosions. Globally, aspherical structures in SN explosions are thought to encode information regarding the underlying explosion mechanism. However, the exact explosion geometries from the inner cores to the outer envelopes are poorly understood.<i>Methods.<i/> Here, we present photometric, spectroscopic, and polarimetric observations of the Type IIP SN 2021yja and discuss its explosion geometry in comparison to those of other Type IIP SNe that show large-scale aspherical structures in their hydrogen envelopes (SNe 2012aw, 2013ej and 2017gmr).<i>Results.<i/> During the plateau phase, SNe 2012aw and 2021yja exhibit high continuum polarization characterized by two components with perpendicular polarization angles. This behavior can be interpreted as being due to a bipolar explosion, where the SN ejecta is composed of a polar (energetic) component and an equatorial (bulk) component. In such a bipolar explosion, an aspherical axis created by the polar ejecta would dominate at early phases, while the perpendicular axis along the equatorial ejecta would emerge at late phases after the photosphere in the polar ejecta has receded. Our interpretation of the explosions in SNe 2012aw and 2021yja as bipolar is also supported by other observational properties, including the time evolution of the line velocities and the line shapes in the nebular spectra. The polarization of other Type IIP SNe that show large-scale aspherical structures in the hydrogen envelope (SNe 2013ej and 2017gmr) is also consistent with the bipolar-explosion scenario, although this is not conclusive.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141618298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1051/0004-6361/202348175
Nicolina Chrysaphi, Milan Maksimovic, Eduard P. Kontar, Antonio Vecchio, Xingyao Chen, Aikaterini Pesini
A large arsenal of space-based and ground-based instruments is dedicated to the observation of radio emissions, whether they originate within our solar system or not. Radio photons interact with anisotropic density fluctuations in the heliosphere which can alter their trajectory and influence the properties that are deduced from observations. This is particularly evident in solar radio observations, where anisotropic scattering leads to highly directional radio emissions. Consequently, observers at varying locations will measure different properties, including different source sizes, source positions, and intensities. However, it is not known whether the measurements of the decay time of solar radio bursts are also affected by the observer’s position. Decay times are dominated by scattering effects, and so are frequently used as proxies of the level of density fluctuations in the heliosphere, making the identification of any location-related dependence crucial. We combine multi-vantage observations of interplanetary Type III bursts from four non-collinear, angularly separated spacecraft with simulations to investigate the dependence of the decay- and rise-time measurements on the separation of the observer from the source. We propose a function to characterise the entire time profile of radio signals, allowing for the simultaneous estimation of the peak flux, decay time, and rise time, while demonstrating that the rise phase of radio bursts is non-exponential, having a non-constant growth rate. We determine that the decay and rise times are independent of the observer’s position, identifying them as the only properties that remain unaffected and thus do not require corrections for the observer’s location. Moreover, we examine the ratio between the rise and decay times and find that it does not depend on the frequency. Therefore, we provide the first evidence that the rise phase is also significantly impacted by scattering effects, adding to our understanding of the plasma emission process.
大量天基和地基仪器专门用于观测无线电辐射，无论它们是否来自太阳系内部。射电光子与日光层中各向异性的密度波动相互作用，会改变其轨迹并影响从观测中推导出的特性。这一点在太阳射电观测中尤为明显，各向异性散射导致射电发射具有高度方向性。因此，不同位置的观测者会测量到不同的属性，包括不同的源大小、源位置和强度。然而，太阳射电暴衰减时间的测量是否也会受到观测者位置的影响，目前还不得而知。衰减时间主要受散射效应的影响，因此经常被用作日光层密度波动水平的代用指标，因此识别任何与位置相关的依赖性至关重要。我们将从四个非共线、角度相距较远的航天器上对行星际 III 型爆发进行的多视角观测与模拟相结合，研究衰减和上升时间测量值与观测者与源的距离的关系。我们提出了一个描述无线电信号整个时间曲线的函数，可以同时估算峰值通量、衰减时间和上升时间，同时证明无线电脉冲串的上升阶段是非指数的，具有非恒定的增长率。我们确定衰减时间和上升时间与观测者的位置无关，确定它们是唯一不受影响的特性，因此不需要对观测者的位置进行修正。此外，我们研究了上升时间和衰减时间之间的比率，发现它与频率无关。因此，我们首次证明了上升阶段也会受到散射效应的显著影响，从而加深了我们对等离子体发射过程的理解。
{"title":"First determination of the angular dependence of rise and decay times of solar radio bursts using multi-spacecraft observations","authors":"Nicolina Chrysaphi, Milan Maksimovic, Eduard P. Kontar, Antonio Vecchio, Xingyao Chen, Aikaterini Pesini","doi":"10.1051/0004-6361/202348175","DOIUrl":"https://doi.org/10.1051/0004-6361/202348175","url":null,"abstract":"A large arsenal of space-based and ground-based instruments is dedicated to the observation of radio emissions, whether they originate within our solar system or not. Radio photons interact with anisotropic density fluctuations in the heliosphere which can alter their trajectory and influence the properties that are deduced from observations. This is particularly evident in solar radio observations, where anisotropic scattering leads to highly directional radio emissions. Consequently, observers at varying locations will measure different properties, including different source sizes, source positions, and intensities. However, it is not known whether the measurements of the decay time of solar radio bursts are also affected by the observer’s position. Decay times are dominated by scattering effects, and so are frequently used as proxies of the level of density fluctuations in the heliosphere, making the identification of any location-related dependence crucial. We combine multi-vantage observations of interplanetary Type III bursts from four non-collinear, angularly separated spacecraft with simulations to investigate the dependence of the decay- and rise-time measurements on the separation of the observer from the source. We propose a function to characterise the entire time profile of radio signals, allowing for the simultaneous estimation of the peak flux, decay time, and rise time, while demonstrating that the rise phase of radio bursts is non-exponential, having a non-constant growth rate. We determine that the decay and rise times are independent of the observer’s position, identifying them as the only properties that remain unaffected and thus do not require corrections for the observer’s location. Moreover, we examine the ratio between the rise and decay times and find that it does not depend on the frequency. Therefore, we provide the first evidence that the rise phase is also significantly impacted by scattering effects, adding to our understanding of the plasma emission process.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141584435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.1051/0004-6361/202450721
D. Schaerer, R. Marques-Chaves, M. Xiao, D. Korber
We report the discovery of a compact star-forming galaxy at z = 9.380 in the GOODS-North field (named GN-z9p4), which shows numerous strong UV-optical emission lines and a single UV line, N IV] λ1486. This makes GN-z9p4 the third-highest redshift N-emitter known to date. We determined the nebular abundances of H, C, N, O and Ne, along with the size and other physical properties of this object, then compared them to those of the other N-emitters known so far and to other star-forming galaxies. Using the direct method, we found a metallicity of 12 + log(O/H) = 7.37 ± 0.15, which stands as one of the lowest among N-emitters. The N/O abundance ratio is highly super-solar, while C/O and Ne/O are normal compared to other galaxies at low metallicity. We show that the compactness of GN-z9p4 (with an effective radius of 118 ± 16 pc at 2 μm) and other N-emitters translates to very high stellar mass and star formation rate (SFR) surface densities, which could serve as a criterium for identifying other N-emitters. Future studies and larger samples are needed to understand these rare, and enigmatic objects that have only recently been discovered.
我们报告在 GOODS-North 星场发现了一个 z = 9.380 的紧凑型恒星形成星系（命名为 GN-z9p4），它显示了许多强紫外光发射线和一条紫外线 N IV] λ1486。这使得 GN-z9p4 成为迄今所知红移第三高的 N 发射器。我们测定了这个天体的 H、C、N、O 和 Ne 的星云丰度，以及它的大小和其他物理特性，然后将它们与目前已知的其他 N 发射体和其他恒星形成星系进行了比较。利用直接法，我们发现该天体的金属性为 12 + log(O/H) = 7.37 ± 0.15，是 N 发射体中金属性最低的天体之一。N/O丰度比高度超太阳，而C/O和Ne/O与其他低金属度星系相比则正常。我们的研究表明，GN-z9p4（2 μm处有效半径为118 ± 16 pc）和其他N-发射体的紧凑性可以转化为非常高的恒星质量和恒星形成率（SFR）表面密度，这可以作为识别其他N-发射体的标准。要了解这些最近才被发现的罕见神秘天体，还需要未来的研究和更大的样本。
{"title":"Discovery of a new N-emitter in the epoch of reionization","authors":"D. Schaerer, R. Marques-Chaves, M. Xiao, D. Korber","doi":"10.1051/0004-6361/202450721","DOIUrl":"https://doi.org/10.1051/0004-6361/202450721","url":null,"abstract":"We report the discovery of a compact star-forming galaxy at <i>z<i/> = 9.380 in the GOODS-North field (named GN-z9p4), which shows numerous strong UV-optical emission lines and a single UV line, N IV] <i>λ<i/>1486. This makes GN-z9p4 the third-highest redshift N-emitter known to date. We determined the nebular abundances of H, C, N, O and Ne, along with the size and other physical properties of this object, then compared them to those of the other N-emitters known so far and to other star-forming galaxies. Using the direct method, we found a metallicity of 12 + log(O/H) = 7.37 ± 0.15, which stands as one of the lowest among N-emitters. The N/O abundance ratio is highly super-solar, while C/O and Ne/O are normal compared to other galaxies at low metallicity. We show that the compactness of GN-z9p4 (with an effective radius of 118 ± 16 pc at 2 μm) and other N-emitters translates to very high stellar mass and star formation rate (SFR) surface densities, which could serve as a criterium for identifying other N-emitters. Future studies and larger samples are needed to understand these rare, and enigmatic objects that have only recently been discovered.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141545976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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