ABSTRACT The dependence of the Rosseland Mean Opacity (RMO) on the equation of state and the number of included atomic levels of iron ions prevalent at the solar radiative/convection boundary is investigated. The ‘chemical picture’ Mihalas–Hummer–Däppen (MHD) equation-of-state (EOS), and its variant QMHD–EOS, are studied at two representative temperature–density sets at the base of the convection zone and the Sandia Z experiment: (2 × 106 K, 1023/cc) and (2.11 × 106 K, 3.16 × 1022/cc), respectively. It is found that whereas the new atomic data sets from accurate R-matrix calculations for opacities (RMOP) are vastly overcomplete, involving hundreds to over a thousand levels of each of the three Fe ions considered – Fe xvii, Fe xviii, Fe xix – the EOS constrains contributions to RMOs by relatively fewer levels. The RMOP iron opacity spectrum is quite different from the Opacity Project distorted wave model and shows considerably more plasma broadening effects. This work points to possible improvements needed in the EOS for opacities in high-energy–density plasma sources.
{"title":"Interface of Equation-of-State, Atomic Data and Opacities in the Solar Problem","authors":"Anil K Pradhan","doi":"10.1093/mnrasl/slad154","DOIUrl":"https://doi.org/10.1093/mnrasl/slad154","url":null,"abstract":"ABSTRACT The dependence of the Rosseland Mean Opacity (RMO) on the equation of state and the number of included atomic levels of iron ions prevalent at the solar radiative/convection boundary is investigated. The ‘chemical picture’ Mihalas–Hummer–Däppen (MHD) equation-of-state (EOS), and its variant QMHD–EOS, are studied at two representative temperature–density sets at the base of the convection zone and the Sandia Z experiment: (2 × 106 K, 1023/cc) and (2.11 × 106 K, 3.16 × 1022/cc), respectively. It is found that whereas the new atomic data sets from accurate R-matrix calculations for opacities (RMOP) are vastly overcomplete, involving hundreds to over a thousand levels of each of the three Fe ions considered – Fe xvii, Fe xviii, Fe xix – the EOS constrains contributions to RMOs by relatively fewer levels. The RMOP iron opacity spectrum is quite different from the Opacity Project distorted wave model and shows considerably more plasma broadening effects. This work points to possible improvements needed in the EOS for opacities in high-energy–density plasma sources.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135647221","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}
ABSTRACT An explanation is provided for flat-top electron distributions observed at the bow shock. It is shown that flat-tops are produced by the stochastic wave energization (SWE) mechanism. First, we demonstrate that flat-tops in one-dimensional (1D) reduced distribution functions correspond to rings in 2D distribution functions, or to shell distributions in 3D. The velocity of the ring/shell corresponds to the E × B velocity due to the wave electric field, $V_{mathrm{ E}{times }mathrm{ B}}=tilde{E}_perp /B$, which is a natural consequence of the SWE process. The identification of processes responsible for electron flat-top distributions was made with magnetospheric multiscale measurements supported by test-particle simulations.
{"title":"Origin of flat-top electron distributions at the Earth’s bow shock","authors":"Krzysztof Stasiewicz","doi":"10.1093/mnrasl/slad146","DOIUrl":"https://doi.org/10.1093/mnrasl/slad146","url":null,"abstract":"ABSTRACT An explanation is provided for flat-top electron distributions observed at the bow shock. It is shown that flat-tops are produced by the stochastic wave energization (SWE) mechanism. First, we demonstrate that flat-tops in one-dimensional (1D) reduced distribution functions correspond to rings in 2D distribution functions, or to shell distributions in 3D. The velocity of the ring/shell corresponds to the E × B velocity due to the wave electric field, $V_{mathrm{ E}{times }mathrm{ B}}=tilde{E}_perp /B$, which is a natural consequence of the SWE process. The identification of processes responsible for electron flat-top distributions was made with magnetospheric multiscale measurements supported by test-particle simulations.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135646527","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}
Timur A Dzhatdoev, Egor I Podlesnyi, Grigory I Rubtsov
Abstract The extragalactic magnetic field (EGMF) could be probed with γ-ray observations of distant sources. Primary very high energy (VHE) γ-rays from these sources absorb on extragalactic background light photons, and secondary electrons/positrons from the pair production acts create cascade γ-rays. These cascade γ-rays could be detected with space γ-ray telescopes such as Fermi-LAT. The γ-ray burst GRB 221009A was an exceptionally bright transient well suited for intergalactic γ-ray propagation studies. Using publicly-available Fermi-LAT data, we obtain upper limits on the spectrum of delayed emission from GRB 221009A during the time windows of 10, 30, and 90 days after the burst, and compare these with model spectra calculated for various EGMF strengths B, obtaining constraints on B. We show that the values of B between 10−20 G and 10−18 G are excluded.
{"title":"First constraints on the strength of the extragalactic magnetic field from γ-ray observations of GRB 221009A","authors":"Timur A Dzhatdoev, Egor I Podlesnyi, Grigory I Rubtsov","doi":"10.1093/mnrasl/slad142","DOIUrl":"https://doi.org/10.1093/mnrasl/slad142","url":null,"abstract":"Abstract The extragalactic magnetic field (EGMF) could be probed with γ-ray observations of distant sources. Primary very high energy (VHE) γ-rays from these sources absorb on extragalactic background light photons, and secondary electrons/positrons from the pair production acts create cascade γ-rays. These cascade γ-rays could be detected with space γ-ray telescopes such as Fermi-LAT. The γ-ray burst GRB 221009A was an exceptionally bright transient well suited for intergalactic γ-ray propagation studies. Using publicly-available Fermi-LAT data, we obtain upper limits on the spectrum of delayed emission from GRB 221009A during the time windows of 10, 30, and 90 days after the burst, and compare these with model spectra calculated for various EGMF strengths B, obtaining constraints on B. We show that the values of B between 10−20 G and 10−18 G are excluded.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135744631","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}
T. Asano, Daisuke Kawata, Michiko S. Fujii, Junichi Baba
Theoretical models of spiral arms suggest that the spiral arms provoke a vertical bulk motion in disc stars. By analysing the breathing motion, a coherent asymmetric vertical motion around the mid-plane of the Milky Way disc, with Gaia DR3, we found that a compressing breathing motion presents along the Local arm. On the other hand, with an N-body simulation of an isolated Milky Way-like disc galaxy, we found that the transient and dynamic spiral arms induce compressing breathing motions when the arms are in the growth phase, while the expanding breathing motion appears in the disruption phase. The observed clear alignment of the compressing breathing motion with the Local arm is similar to what is seen in the growth phase of the simulated spiral arms. Hence, we suggest that the Local arm’s compressing breathing motion can be explained by the Local arm being in the growth phase of a transient and dynamic spiral arm. We also identified the tentative signatures of the expanding breathing motion associated with the Perseus arm and also the Outer arm coinciding with the compressing breathing motion. This may infer that the Perseus and Outer arms are in the disruption and growth phases, respectively.
{"title":"Growing Local arm inferred by the breathing motion","authors":"T. Asano, Daisuke Kawata, Michiko S. Fujii, Junichi Baba","doi":"10.1093/mnrasl/slad190","DOIUrl":"https://doi.org/10.1093/mnrasl/slad190","url":null,"abstract":"Theoretical models of spiral arms suggest that the spiral arms provoke a vertical bulk motion in disc stars. By analysing the breathing motion, a coherent asymmetric vertical motion around the mid-plane of the Milky Way disc, with Gaia DR3, we found that a compressing breathing motion presents along the Local arm. On the other hand, with an N-body simulation of an isolated Milky Way-like disc galaxy, we found that the transient and dynamic spiral arms induce compressing breathing motions when the arms are in the growth phase, while the expanding breathing motion appears in the disruption phase. The observed clear alignment of the compressing breathing motion with the Local arm is similar to what is seen in the growth phase of the simulated spiral arms. Hence, we suggest that the Local arm’s compressing breathing motion can be explained by the Local arm being in the growth phase of a transient and dynamic spiral arm. We also identified the tentative signatures of the expanding breathing motion associated with the Perseus arm and also the Outer arm coinciding with the compressing breathing motion. This may infer that the Perseus and Outer arms are in the disruption and growth phases, respectively.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139324001","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}
Alexander A Marchuk, Aleksandr V Mosenkov, Ilia V Chugunov, Valeria S Kostiuk, Maria N Skryabina, Vladimir P Reshetnikov
ABSTRACT The knowledge of the positions of the corotation resonance in spiral arms is a key way to estimate their pattern speed, which is a fundamental parameter determining the galaxy dynamics. Various methods for its estimation have been developed, but they all demonstrate certain limitations and a lack of agreement with each other. Here, we present a new method for estimating the corotation radius. This method takes into account the shape of the profile across the arm and its width and, thus, only photometric data is needed. The significance of the method is that it can potentially be used for the farthest galaxies with measurable spiral arms. We apply it to a sample of local galaxies from Savchenko et al.(2020) and compare the obtained corotation radii with those previously measured in the literature by other methods. Our results are in good agreement with the literature. We also apply the new method to distant galaxies from the COSMOS field. For the first time, corotation locations for galaxies with photometric redshifts up to z ∼ 0.9 are measured.
旋臂中旋向共振的位置是估计旋臂模式速度的关键，而模式速度是决定星系动力学的基本参数。目前已经开发了各种估算方法，但它们都有一定的局限性，并且彼此之间缺乏一致性。在此，我们提出了一种估计旋转半径的新方法。该方法考虑了臂侧轮廓的形状及其宽度，因此只需要光度数据。该方法的意义在于，它可以潜在地用于具有可测量旋臂的最远星系。我们将其应用于Savchenko et al.(2020)的本地星系样本，并将获得的旋转半径与文献中先前通过其他方法测量的半径进行比较。我们的结果与文献很好地吻合。我们还将新方法应用于来自COSMOS场的遥远星系。第一次测量了光度红移达到z ~ 0.9的星系的旋转位置。
{"title":"A new, purely photometric method for determination of resonance locations in spiral galaxies","authors":"Alexander A Marchuk, Aleksandr V Mosenkov, Ilia V Chugunov, Valeria S Kostiuk, Maria N Skryabina, Vladimir P Reshetnikov","doi":"10.1093/mnrasl/slad141","DOIUrl":"https://doi.org/10.1093/mnrasl/slad141","url":null,"abstract":"ABSTRACT The knowledge of the positions of the corotation resonance in spiral arms is a key way to estimate their pattern speed, which is a fundamental parameter determining the galaxy dynamics. Various methods for its estimation have been developed, but they all demonstrate certain limitations and a lack of agreement with each other. Here, we present a new method for estimating the corotation radius. This method takes into account the shape of the profile across the arm and its width and, thus, only photometric data is needed. The significance of the method is that it can potentially be used for the farthest galaxies with measurable spiral arms. We apply it to a sample of local galaxies from Savchenko et al.(2020) and compare the obtained corotation radii with those previously measured in the literature by other methods. Our results are in good agreement with the literature. We also apply the new method to distant galaxies from the COSMOS field. For the first time, corotation locations for galaxies with photometric redshifts up to z ∼ 0.9 are measured.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135458435","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}
ABSTRACT The study of the chemistry of the stellar populations in globular clusters (GCs) is a fundamental task to unveil their formation in the high-redshift universe and to reconstruct the build-up of our Galaxy. Using metallicity estimates from BP/RP low-resolution Gaia DR3 spectra, a recent work presented the surprizing detection of two stellar populations with distinct metallicities in the stellar stream of the GC NGC 5904, otherwise considered a mono-metallic system. The presence of these two populations, with [Fe/H] ∼ −1.4 and [Fe/H] ∼ −2.0 dex, was taken as the evidence of a merger origin of the cluster. In this Letter, using the same data set complemented by new robust metallicity estimates, we carry out a detailed analysis of the metallicity distribution of stars belonging both to the cluster and to its stellar stream, explicitly focusing on the subtle effects of data systematics. We demonstrate that the population at [Fe/H] ∼ −2.0 dex is a data artefact due to error systematics, affecting especially faint stars. The new higher quality metallicity sample corroborates this finding, and it indicates the presence of only one population of stars with metallicity of [Fe/H] ∼ −1.3 dex, in agreement with previous literature studies. We, therefore, conclude that both NGC 5904 and its stellar stream are mono-metallic systems, and emphasize the need of carefully examining systematic effects in large and complex data.
{"title":"A cautionary lesson from Gaia systematics: the mono-metallic globular cluster NGC 5904","authors":"Paolo Bianchini, Alessandra Mastrobuono-Battisti","doi":"10.1093/mnrasl/slad140","DOIUrl":"https://doi.org/10.1093/mnrasl/slad140","url":null,"abstract":"ABSTRACT The study of the chemistry of the stellar populations in globular clusters (GCs) is a fundamental task to unveil their formation in the high-redshift universe and to reconstruct the build-up of our Galaxy. Using metallicity estimates from BP/RP low-resolution Gaia DR3 spectra, a recent work presented the surprizing detection of two stellar populations with distinct metallicities in the stellar stream of the GC NGC 5904, otherwise considered a mono-metallic system. The presence of these two populations, with [Fe/H] ∼ −1.4 and [Fe/H] ∼ −2.0 dex, was taken as the evidence of a merger origin of the cluster. In this Letter, using the same data set complemented by new robust metallicity estimates, we carry out a detailed analysis of the metallicity distribution of stars belonging both to the cluster and to its stellar stream, explicitly focusing on the subtle effects of data systematics. We demonstrate that the population at [Fe/H] ∼ −2.0 dex is a data artefact due to error systematics, affecting especially faint stars. The new higher quality metallicity sample corroborates this finding, and it indicates the presence of only one population of stars with metallicity of [Fe/H] ∼ −1.3 dex, in agreement with previous literature studies. We, therefore, conclude that both NGC 5904 and its stellar stream are mono-metallic systems, and emphasize the need of carefully examining systematic effects in large and complex data.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135246968","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. Semczuk, E. Łokas, A. de Lorenzo-Cáceres, E. Athanassoula
Double bars make up a significant fraction of barred galaxies. We propose a new formation scenario for double bars that involves tidal interactions. We demonstrate the viability of this scenario using two examples of simulated galaxies from run TNG50-1 of the IllustrisTNG project. In the proposed scenario the inner bar forms first, either in isolation, via instabilities, or through previous tides. The outer bar forms later from the material that is tidally distorted by a strong interaction. The inner and outer bars formed this way rotate with different pattern speeds and can be mistaken for a single bar when their phases align. The double-barred structure is stable and can last for at least 3 Gyr. The inner bars of the tidally induced double bars can also have big sizes, which can possibly explain the origin of sizable inner bars recently found in some galaxies.
{"title":"A new tidal scenario for double bar formation","authors":"M. Semczuk, E. Łokas, A. de Lorenzo-Cáceres, E. Athanassoula","doi":"10.1093/mnrasl/slad175","DOIUrl":"https://doi.org/10.1093/mnrasl/slad175","url":null,"abstract":"Double bars make up a significant fraction of barred galaxies. We propose a new formation scenario for double bars that involves tidal interactions. We demonstrate the viability of this scenario using two examples of simulated galaxies from run TNG50-1 of the IllustrisTNG project. In the proposed scenario the inner bar forms first, either in isolation, via instabilities, or through previous tides. The outer bar forms later from the material that is tidally distorted by a strong interaction. The inner and outer bars formed this way rotate with different pattern speeds and can be mistaken for a single bar when their phases align. The double-barred structure is stable and can last for at least 3 Gyr. The inner bars of the tidally induced double bars can also have big sizes, which can possibly explain the origin of sizable inner bars recently found in some galaxies.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139334563","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}
ABSTRACT The spectral index ns of scalar perturbation is the significant initial condition set by inflation theory for our observable Universe. According to Planck results, current constraint is ns = 0.965 ± 0.004, while an exact scale-invariant Harrison–Zeldovich spectrum, i.e. ns = 1, has been ruled out at 8.4σ significance level. However, it is well-known that the standard Lambda cold dark matter model is suffering from the Hubble tension, which is at ∼5σ significance level. This inconsistency likely indicates that the comoving sound horizon at last scattering surface is actually lower than expected, which so seems to be calling for the return of ns = 1. Here, in light of recent observations we find strong evidence for a ns = 1 universe. And we show that if so, it would be confirmed conclusively by CMB-S4 experiment.
{"title":"Return of harrison-zeldovich spectrum in light of recent cosmological tensions","authors":"Jun-Qian Jiang, Gen Ye, Yun-Song Piao","doi":"10.1093/mnrasl/slad137","DOIUrl":"https://doi.org/10.1093/mnrasl/slad137","url":null,"abstract":"ABSTRACT The spectral index ns of scalar perturbation is the significant initial condition set by inflation theory for our observable Universe. According to Planck results, current constraint is ns = 0.965 ± 0.004, while an exact scale-invariant Harrison–Zeldovich spectrum, i.e. ns = 1, has been ruled out at 8.4σ significance level. However, it is well-known that the standard Lambda cold dark matter model is suffering from the Hubble tension, which is at ∼5σ significance level. This inconsistency likely indicates that the comoving sound horizon at last scattering surface is actually lower than expected, which so seems to be calling for the return of ns = 1. Here, in light of recent observations we find strong evidence for a ns = 1 universe. And we show that if so, it would be confirmed conclusively by CMB-S4 experiment.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135472444","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 Drevon, F Millour, P Cruzalèbes, C Paladini, P Scicluna, A Matter, A Chiavassa, M Montargès, E Cannon, F Allouche, K-H Hofmann, S Lagarde, B Lopez, A Meilland, R Petrov, S Robbe-Dubois, D Schertl, G Zins, P Ábrahám, P Berio, Th Henning, J Hron, J W Isbell, W Jaffe, L Labadie, J Varga, G Weigelt, J Woillez, R van Boekel, E Pantin, W C Danchi, A de Koter, V Gámez Rosas, M R Hogerheijde, J Leftley, P Stee, R Waters
ABSTRACT From Nov. 2019 to May 2020, the red supergiant star Betelgeuse experienced an unprecedented drop of brightness in the visible domain called the Great Dimming event (GDE). Large atmospheric dust clouds and large photospheric convective features are suspected to be responsible for it. To better understand the dimming event, we used mid-infrared long-baseline spectro-interferometric measurements of Betelgeuse taken with the Very Large Telescope Interferometer/Multi AperTure mid-Infrared SpectroScopic Experiment (VLTI/MATISSE) instrument before (Dec. 2018), during (Feb. 2020), and after (Dec. 2020) the GDE. We present data in the 3.98–4.15 µm range to cover SiO spectral features molecules as well as adjacent continuum. We have employed geometrical models, image reconstruction, as well as radiative transfer models to monitor the spatial distribution of SiO over the stellar surface. We find a strongly inhomogeneous spatial distribution of SiO that appears to be looking very different between our observing epochs, indicative of a vigorous activity in the stellar atmosphere. The contrast of our images is small in the pseudo-continuum for all epochs, implying that our MATISSE observations support both cold spot and dust cloud model.
{"title":"Images of Betelgeuse with VLTI/MATISSE across the Great Dimming","authors":"J Drevon, F Millour, P Cruzalèbes, C Paladini, P Scicluna, A Matter, A Chiavassa, M Montargès, E Cannon, F Allouche, K-H Hofmann, S Lagarde, B Lopez, A Meilland, R Petrov, S Robbe-Dubois, D Schertl, G Zins, P Ábrahám, P Berio, Th Henning, J Hron, J W Isbell, W Jaffe, L Labadie, J Varga, G Weigelt, J Woillez, R van Boekel, E Pantin, W C Danchi, A de Koter, V Gámez Rosas, M R Hogerheijde, J Leftley, P Stee, R Waters","doi":"10.1093/mnrasl/slad138","DOIUrl":"https://doi.org/10.1093/mnrasl/slad138","url":null,"abstract":"ABSTRACT From Nov. 2019 to May 2020, the red supergiant star Betelgeuse experienced an unprecedented drop of brightness in the visible domain called the Great Dimming event (GDE). Large atmospheric dust clouds and large photospheric convective features are suspected to be responsible for it. To better understand the dimming event, we used mid-infrared long-baseline spectro-interferometric measurements of Betelgeuse taken with the Very Large Telescope Interferometer/Multi AperTure mid-Infrared SpectroScopic Experiment (VLTI/MATISSE) instrument before (Dec. 2018), during (Feb. 2020), and after (Dec. 2020) the GDE. We present data in the 3.98–4.15 µm range to cover SiO spectral features molecules as well as adjacent continuum. We have employed geometrical models, image reconstruction, as well as radiative transfer models to monitor the spatial distribution of SiO over the stellar surface. We find a strongly inhomogeneous spatial distribution of SiO that appears to be looking very different between our observing epochs, indicative of a vigorous activity in the stellar atmosphere. The contrast of our images is small in the pseudo-continuum for all epochs, implying that our MATISSE observations support both cold spot and dust cloud model.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135579808","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}
B T Bolin, F J Masci, D A Duev, J W Milburn, J D Neill, J N Purdum, C Avdellidou, Y-C Cheng, M Delbo, C Fremling, M Ghosal, Z-Y Lin, C M Lisse, A Mahabal, M Saki
ABSTRACT Long-period comets are planetesimal remnants constraining the environment and volatiles of the protoplanetary disc. We report the discovery of hyperbolic long-period comet C/2022 E3 Zwicky Transient Facility (ZTF), which has a perihelion ∼1.11 au, an eccentricity ≳1 and an inclination ∼109°, from images taken with the Palomar 48-inch telescope during morning twilight on 2022 March 2. Additionally, we report the characterization of C/2022 E3 (ZTF) from observations taken with the Palomar 200-inch, the Palomar 60-inch, and the NASA Infrared Telescope Facility in early 2023 February to 2023 March when the comet passed within ∼0.28 au of the Earth and reached a visible magnitude of ∼5. We measure g–r = 0.70 ± 0.01, r–i = 0.20 ± 0.01, i–z = 0.06 ± 0.01, z–J = 0.90 ± 0.01, J–H = 0.38 ± 0.01, and H–K = 0.15 ± 0.01 colours for the comet from observations. We measure the A(0°)fρ (0.8 μm) in a 6500 km radius from the nucleus of 1483 ± 40 cm, and CN, C3, and C2 production of 5.43 ± 0.11 × 1025, 2.01 ± 0.04 × 1024, and 3.08 ± 0.5 × 1025 mol s−1, similar to other long-period comets. We additionally observe the appearance of jet-like structures at a scale of ∼4000 km in wide-field g-band images, which may be caused by the presence of CN gas in the near-nucleus coma.
{"title":"Palomar discovery and initial characterization of naked-eye long period comet C/2022 E3 (ZTF)","authors":"B T Bolin, F J Masci, D A Duev, J W Milburn, J D Neill, J N Purdum, C Avdellidou, Y-C Cheng, M Delbo, C Fremling, M Ghosal, Z-Y Lin, C M Lisse, A Mahabal, M Saki","doi":"10.1093/mnrasl/slad139","DOIUrl":"https://doi.org/10.1093/mnrasl/slad139","url":null,"abstract":"ABSTRACT Long-period comets are planetesimal remnants constraining the environment and volatiles of the protoplanetary disc. We report the discovery of hyperbolic long-period comet C/2022 E3 Zwicky Transient Facility (ZTF), which has a perihelion ∼1.11 au, an eccentricity ≳1 and an inclination ∼109°, from images taken with the Palomar 48-inch telescope during morning twilight on 2022 March 2. Additionally, we report the characterization of C/2022 E3 (ZTF) from observations taken with the Palomar 200-inch, the Palomar 60-inch, and the NASA Infrared Telescope Facility in early 2023 February to 2023 March when the comet passed within ∼0.28 au of the Earth and reached a visible magnitude of ∼5. We measure g–r = 0.70 ± 0.01, r–i = 0.20 ± 0.01, i–z = 0.06 ± 0.01, z–J = 0.90 ± 0.01, J–H = 0.38 ± 0.01, and H–K = 0.15 ± 0.01 colours for the comet from observations. We measure the A(0°)fρ (0.8 μm) in a 6500 km radius from the nucleus of 1483 ± 40 cm, and CN, C3, and C2 production of 5.43 ± 0.11 × 1025, 2.01 ± 0.04 × 1024, and 3.08 ± 0.5 × 1025 mol s−1, similar to other long-period comets. We additionally observe the appearance of jet-like structures at a scale of ∼4000 km in wide-field g-band images, which may be caused by the presence of CN gas in the near-nucleus coma.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"2010 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135579807","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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