Pub Date : 2024-08-08DOI: 10.1051/0004-6361/202450704
W. Dethier, B. Tessore
In recent years it has become common practice to divide observed transit absorption spectra by synthetic absorption spectra computed for the transit of an atmosphere-less planet. This action supposedly corrects the observed absorption spectrum, leaving the sole atmospheric absorption signature free from the biases induced by stellar rotation and centre-to-limb variations. We aim to show that while this practice is beneficial, it does not completely correct the absorption spectrum from the stellar distortions and that some residual biases remain, leaving a possibly altered atmospheric signature. By reducing the problem to its most basic form, we show that dividing the observed absorption spectrum by a synthetic absorption spectrum of the planet does not isolate the pure atmospheric absorption signature. We also used simulated synthetic transit observations to assess the magnitude of these residual biases in typical transit observations. We show that dividing the observed absorption spectrum by the planetary absorption spectrum results in an atmospheric signature modulated by the ratio of the flux behind the atmosphere and the flux behind the planet. Depending on the non-homogeneity of the stellar spectrum, this leads to distorted atmospheric signatures. Eventually, directly analysing these biased signatures will lead to wrong estimates of planetary atmosphere properties.
{"title":"Assessing the residual biases in high-resolution transit absorption spectra correction","authors":"W. Dethier, B. Tessore","doi":"10.1051/0004-6361/202450704","DOIUrl":"https://doi.org/10.1051/0004-6361/202450704","url":null,"abstract":"In recent years it has become common practice to divide observed transit absorption spectra by synthetic absorption spectra computed for the transit of an atmosphere-less planet. This action supposedly corrects the observed absorption spectrum, leaving the sole atmospheric absorption signature free from the biases induced by stellar rotation and centre-to-limb variations. We aim to show that while this practice is beneficial, it does not completely correct the absorption spectrum from the stellar distortions and that some residual biases remain, leaving a possibly altered atmospheric signature. By reducing the problem to its most basic form, we show that dividing the observed absorption spectrum by a synthetic absorption spectrum of the planet does not isolate the pure atmospheric absorption signature. We also used simulated synthetic transit observations to assess the magnitude of these residual biases in typical transit observations. We show that dividing the observed absorption spectrum by the planetary absorption spectrum results in an atmospheric signature modulated by the ratio of the flux behind the atmosphere and the flux behind the planet. Depending on the non-homogeneity of the stellar spectrum, this leads to distorted atmospheric signatures. Eventually, directly analysing these biased signatures will lead to wrong estimates of planetary atmosphere properties.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"51 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141928295","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}
Pub Date : 2024-08-08DOI: 10.1051/0004-6361/202450263
Devogèle Maxime, Luca Buzzi, Marco Micheli, Juan Luis Cano, L. Conversi, E. Jehin, M. Ferrais, Francisco Ocaña, Dora Föhring, Charlie Drury, Z. Benkhaldoun, Peter Jenniskens
Near-Earth objects (NEOs) on an impact course with Earth can move at high angular speeds. Understanding their properties, including their rotation state, is crucial for assessing impact risks and mitigation strategies. Traditional photometric methods face challenges in accurately collecting data on fast-moving NEOs. This study introduces an innovative approach to aperture photometry, tailored to analyzing trailed images of fast-moving NEOs. Our primary aim is to extract rotation state information for fast rotators. We applied our approach to the trailed images of three asteroids: 2023 CX1, 2024 BX1, and 2024 EF, which were either on a collision course or on a close fly-by with Earth, resulting in high angular velocities. By adjusting the aperture size, we controlled the effective instantaneous exposure time of the asteroid to increase the sampling rate of photometric variations. This enabled us to detect short rotation periods that would be challenging to derive with conventional methods. Our analysis shows that trailed photometry significantly reduces the overhead time associated with CCD readout, enhancing the sampling rate of the photometric variations. We demonstrate that this technique is particularly effective for fast-moving objects, providing reliable photometric data when the object is at its brightest and closest to Earth. For asteroid 2024 BX1, we detect a rotation period of $2.5888 0.0002$ seconds, the shortest ever recorded. We discuss under what circumstances it is most efficient to use trailed observations coupled with aperture photometry for studying the rotation characteristics of NEOs.
{"title":"Aperture photometry on asteroid trails. Detection of the fastest-rotating near-Earth object","authors":"Devogèle Maxime, Luca Buzzi, Marco Micheli, Juan Luis Cano, L. Conversi, E. Jehin, M. Ferrais, Francisco Ocaña, Dora Föhring, Charlie Drury, Z. Benkhaldoun, Peter Jenniskens","doi":"10.1051/0004-6361/202450263","DOIUrl":"https://doi.org/10.1051/0004-6361/202450263","url":null,"abstract":"Near-Earth objects (NEOs) on an impact course with Earth can move at high angular speeds. Understanding their properties, including their rotation state, is crucial for assessing impact risks and mitigation strategies. Traditional photometric methods face challenges in accurately collecting data on fast-moving NEOs. This study introduces an innovative approach to aperture photometry, tailored to analyzing trailed images of fast-moving NEOs. Our primary aim is to extract rotation state information for fast rotators. We applied our approach to the trailed images of three asteroids: 2023 CX1, 2024 BX1, and 2024 EF, which were either on a collision course or on a close fly-by with Earth, resulting in high angular velocities. By adjusting the aperture size, we controlled the effective instantaneous exposure time of the asteroid to increase the sampling rate of photometric variations. This enabled us to detect short rotation periods that would be challenging to derive with conventional methods. Our analysis shows that trailed photometry significantly reduces the overhead time associated with CCD readout, enhancing the sampling rate of the photometric variations. We demonstrate that this technique is particularly effective for fast-moving objects, providing reliable photometric data when the object is at its brightest and closest to Earth. For asteroid 2024 BX1, we detect a rotation period of $2.5888 0.0002$ seconds, the shortest ever recorded. We discuss under what circumstances it is most efficient to use trailed observations coupled with aperture photometry for studying the rotation characteristics of NEOs.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"30 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927104","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}
Pub Date : 2024-08-08DOI: 10.1051/0004-6361/202449981
A. Santamar'ia-Miranda, I. de Gregorio-Monsalvo, N. Ohashi, J. John Tobin, Jinshi Sai, K. Jes J, rgensen, Yusuke Aso, Zhe-Yu Daniel Lin, Christian Flores, Miyuki Kido, M. Patrick Koch, Woojin Kwon, Chang Won Lee, Zhi-Yun Li, W. Leslie Looney, L. Adele Plunkett, S. Takakuwa, Merel L. R van 't Hoff, P. Jonathan Williams, Hsi-Wei Yen
We present the results of the observations made within the ALMA Large Program called Early Planet Formation in Embedded disks of the Class 0 protostar GSS30 IRS3. Our observations included the 1.3 mm continuum with a resolution of 0 (7.8 au) and several molecular species, including 12CO, 13CO, C18O $CO, and c-C$_ $H$_ $. The dust continuum analysis unveiled a disk-shaped structure with a major axis of sim 200 au. We observed an asymmetry in the minor axis of the continuum emission suggesting that the emission is optically thick and the disk is flared. On the other hand, we identified two prominent bumps along the major axis located at distances of 26 and 50 au from the central protostar. The origin of the bumps remains uncertain and might be an embedded substructure within the disk or the temperature distribution and not the surface density because the continuum emission is optically thick. The 12CO emission reveals a molecular outflow consisting of three distinct components: a collimated component, an intermediate-velocity component exhibiting an hourglass shape, and a wider angle low-velocity component. We associate these components with the coexistence of a jet and a disk wind. The C18O emission traces both a circumstellar disk in Keplerian rotation and the infall of the rotating envelope. We measured a stellar dynamical mass of 0.35pm 0.09 M$_ odot
{"title":"Early Planet Formation in Embedded Disks (eDisk) XVI. Asymmetric dust disk driving a multicomponent molecular outflow in the young Class 0 protostar GSS30 IRS3","authors":"A. Santamar'ia-Miranda, I. de Gregorio-Monsalvo, N. Ohashi, J. John Tobin, Jinshi Sai, K. Jes J, rgensen, Yusuke Aso, Zhe-Yu Daniel Lin, Christian Flores, Miyuki Kido, M. Patrick Koch, Woojin Kwon, Chang Won Lee, Zhi-Yun Li, W. Leslie Looney, L. Adele Plunkett, S. Takakuwa, Merel L. R van 't Hoff, P. Jonathan Williams, Hsi-Wei Yen","doi":"10.1051/0004-6361/202449981","DOIUrl":"https://doi.org/10.1051/0004-6361/202449981","url":null,"abstract":"We present the results of the observations made within the ALMA Large Program called Early Planet Formation in Embedded disks of the Class 0 protostar GSS30 IRS3. Our observations included the 1.3 mm continuum with a resolution of 0 (7.8 au) and several molecular species, including 12CO, 13CO, C18O $CO, and c-C$_ $H$_ $. The dust continuum analysis unveiled a disk-shaped structure with a major axis of sim 200 au. We observed an asymmetry in the minor axis of the continuum emission suggesting that the emission is optically thick and the disk is flared. On the other hand, we identified two prominent bumps along the major axis located at distances of 26 and 50 au from the central protostar. The origin of the bumps remains uncertain and might be an embedded substructure within the disk or the temperature distribution and not the surface density because the continuum emission is optically thick. The 12CO emission reveals a molecular outflow consisting of three distinct components: a collimated component, an intermediate-velocity component exhibiting an hourglass shape, and a wider angle low-velocity component. We associate these components with the coexistence of a jet and a disk wind. The C18O emission traces both a circumstellar disk in Keplerian rotation and the infall of the rotating envelope. We measured a stellar dynamical mass of 0.35pm 0.09 M$_ odot","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"4 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141928887","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202348385
S. Nesbit‐Östman, H. Gunell, M. Hamrin, H. Opgenoorth, Laila Andersson
We aim to quantify the width of the quasi-perpendicular Martian bow shock region to deepen the understanding of why the width is variable and which factors affect it, and to explore the implications on thermalization. To quantify the width, 2074 quasi-perpendicular bow shock crossings from a database were studied. Upstream conditions, such as Mach numbers, dynamic pressure, ion densities, and other factors, were considered. Furthermore, the difference between the downstream and upstream temperature was measured. We found that the shock region width is correlated with the magnetosonic Mach number, the critical ratio, and the overshoot amplitude. The region was found to be anticorrelated with dynamic pressure. The width is not affected by the upstream ion density of the investigated species or by the upstream temperature. The difference between the downstream and upstream temperature is not affected by the shock region width. We found that the factors that affect the stand-off distance of the bow shock, such as the magnetosonic Mach number and dynamic pressure, also affect the width. The width is also positively correlated with the overshoot amplitude, indicating that the structures are coupled or that they are affected by largely the same conditions. The lack of a correlation with the ion temperature difference indicates that the shock region width does not affect the ion thermalization.
{"title":"Width of the quasi-perpendicular bow shock region at Mars","authors":"S. Nesbit‐Östman, H. Gunell, M. Hamrin, H. Opgenoorth, Laila Andersson","doi":"10.1051/0004-6361/202348385","DOIUrl":"https://doi.org/10.1051/0004-6361/202348385","url":null,"abstract":"We aim to quantify the width of the quasi-perpendicular Martian bow shock region to deepen the understanding of why the width is variable and which factors affect it, and to explore the implications on thermalization. To quantify the width, 2074 quasi-perpendicular bow shock crossings from a database were studied. Upstream conditions, such as Mach numbers, dynamic pressure, ion densities, and other factors, were considered. Furthermore, the difference between the downstream and upstream temperature was measured. We found that the shock region width is correlated with the magnetosonic Mach number, the critical ratio, and the overshoot amplitude. The region was found to be anticorrelated with dynamic pressure. The width is not affected by the upstream ion density of the investigated species or by the upstream temperature. The difference between the downstream and upstream temperature is not affected by the shock region width. We found that the factors that affect the stand-off distance of the bow shock, such as the magnetosonic Mach number and dynamic pressure, also affect the width. The width is also positively correlated with the overshoot amplitude, indicating that the structures are coupled or that they are affected by largely the same conditions. The lack of a correlation with the ion temperature difference indicates that the shock region width does not affect the ion thermalization.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"12 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796333","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202348572
J.F. Agui Fernandez, A. de Ugarte Postigo, C. Thone, S. Kobayashi, A. Rossi, K. Toma, M. Jelínek, D. A. Kann, S. Covino, K. Wiersema, D. Hartmann, P. Jakobsson, A. Martin-Carrillo, A. Melandri, M. De Pasquale, G. Pugliese, S. Savaglio, R. Starling, J. Strobl, M. Della Valle, S. de Wet, T. Zafar
Long gamma-ray bursts (GRBs) are produced by the collapse of some very massive stars, that emit ultra-relativistic jets. When the jets collide with the interstellar medium they decelerate and generate the so-called afterglow emission, which has been observed to be polarised. We study the polarimetric evolution of the GRB,210610B afterglow, at $z=1.1341$. This allows us to evaluate the role of geometric and/or magnetic mechanisms in the GRB afterglow polarisation. We observed GRB,210610B using imaging polarimetry with CAFOS on the 2.2 m Calar Alto Telescope and FORS2 on the $4 m Very Large Telescope. Complementary optical spectroscopy was obtained with OSIRIS on the 10.4 m Gran Telescopio Canarias. We studied the GRB light-curve from X-rays to the optical bands and the Spectral Energy Distribution (SED). This allowed us to strongly constrain the line-of-sight extinction. Finally, we studied the GRB host galaxy using optical to NIR data to fit the SED and derive its integrated properties. GRB,210610B had a bright afterglow with a negligible line-of-sight extinction. Polarimetry was obtained at three epochs: during an early plateau phase, at the time when the light curve breaks, and after the light curve steepened. We observe an initial polarisation of $ that goes to zero at the time of the break, and it then again increases to $ with a change in the position angle of $54 deg. The spectrum shows features with very low equivalent widths. This indicate a small amount of material in the line of sight within the host. The lack of dust and the low amount of material in the line of sight to GRB,210610B allowed us to study the intrinsic polarisation of the GRB optical afterglow. The GRB polarisation signals are consistent with ordered magnetic fields in refreshed shock or/and hydrodynamics-scale turbulent fields in the forward shock.
{"title":"Varying linear polarisation in the dust-free gamma-ray burst 210610B","authors":"J.F. Agui Fernandez, A. de Ugarte Postigo, C. Thone, S. Kobayashi, A. Rossi, K. Toma, M. Jelínek, D. A. Kann, S. Covino, K. Wiersema, D. Hartmann, P. Jakobsson, A. Martin-Carrillo, A. Melandri, M. De Pasquale, G. Pugliese, S. Savaglio, R. Starling, J. Strobl, M. Della Valle, S. de Wet, T. Zafar","doi":"10.1051/0004-6361/202348572","DOIUrl":"https://doi.org/10.1051/0004-6361/202348572","url":null,"abstract":"Long gamma-ray bursts (GRBs) are produced by the collapse of some very massive stars, that emit ultra-relativistic jets. When the jets collide with the interstellar medium they decelerate and generate the so-called afterglow emission, which has been observed to be polarised. We study the polarimetric evolution of the GRB,210610B afterglow, at $z=1.1341$. This allows us to evaluate the role of geometric and/or magnetic mechanisms in the GRB afterglow polarisation. We observed GRB,210610B using imaging polarimetry with CAFOS on the 2.2 m Calar Alto Telescope and FORS2 on the $4 m Very Large Telescope. Complementary optical spectroscopy was obtained with OSIRIS on the 10.4 m Gran Telescopio Canarias. We studied the GRB light-curve from X-rays to the optical bands and the Spectral Energy Distribution (SED). This allowed us to strongly constrain the line-of-sight extinction. Finally, we studied the GRB host galaxy using optical to NIR data to fit the SED and derive its integrated properties. GRB,210610B had a bright afterglow with a negligible line-of-sight extinction. Polarimetry was obtained at three epochs: during an early plateau phase, at the time when the light curve breaks, and after the light curve steepened. We observe an initial polarisation of $ that goes to zero at the time of the break, and it then again increases to $ with a change in the position angle of $54 deg. The spectrum shows features with very low equivalent widths. This indicate a small amount of material in the line of sight within the host. The lack of dust and the low amount of material in the line of sight to GRB,210610B allowed us to study the intrinsic polarisation of the GRB optical afterglow. The GRB polarisation signals are consistent with ordered magnetic fields in refreshed shock or/and hydrodynamics-scale turbulent fields in the forward shock.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"11 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796347","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202451052
I. Potravnov, N. Piskunov, T. Ryabchikova
The combination of the surface magnetic and abundance inhomogeneities in chemically peculiar Ap/Bp stars is responsible for their rotationally modulated variability. Within the framework of the fossil field hypothesis, these inhomogeneities are considered to be essentially stable over the main sequence (MS) timescale. However, a small group of Ap/Bp stars show rotational period changes that are not fully understood. Here, we present results of Doppler imaging (DI) of the rapidly rotating Ap star 56 Ari whose changes in period had previously been detected. A reconstruction of the surface distribution of silicon in 56 Ari reveals its complex spot pattern, which is responsible for the rotationally light variability and is correlated with a magnetic field modulation. Comparisons of abundance maps obtained over the unprecedentedly long (for such studies) interval from 1986 to 2014 confirms the stability and rigid rotation of the spot pattern. Thus, we find the period change in 56 Ari is not caused by a rearrangement of the surface magnetic structures and/or atomic diffusion operating on short timescale. It is also unlikely to be explained by the visibility changes of the spots due to the free-body precession of the stellar rotational axis. We briefly discuss possible alternative explanations of the period variability.
化学性质奇特的Ap/Bp星的表面磁性和丰度不均匀性是造成其旋转调制变异性的原因。在化石场假说的框架内，这些不均匀性被认为在主序（MS）时间尺度上基本上是稳定的。然而，有一小部分Ap/Bp恒星表现出的自转周期变化还没有被完全理解。在这里，我们展示了对快速旋转的 Ap 星 56 Ari 的多普勒成像（DI）结果。对 56 Ari 星硅表面分布的重建揭示了其复杂的光斑模式，它是自转光变的原因，并与磁场调制相关。对从 1986 年到 2014 年这一史无前例的长间隔（对此类研究而言）内获得的丰度图进行比较，证实了光斑模式的稳定性和刚性旋转。因此，我们发现 56 Ari 的周期变化不是由表面磁结构的重新排列和/或短时原子扩散引起的。它也不太可能由恒星自转轴的自由体前冲引起的光斑能见度变化来解释。我们简要讨论了周期变化的其他可能解释。
{"title":"Secular stability of surface abundance structures in the rapidly rotating Ap star 56 Ari","authors":"I. Potravnov, N. Piskunov, T. Ryabchikova","doi":"10.1051/0004-6361/202451052","DOIUrl":"https://doi.org/10.1051/0004-6361/202451052","url":null,"abstract":"The combination of the surface magnetic and abundance inhomogeneities in chemically peculiar Ap/Bp stars is responsible for their rotationally modulated variability. Within the framework of the fossil field hypothesis, these inhomogeneities are considered to be essentially stable over the main sequence (MS) timescale. However, a small group of Ap/Bp stars show rotational period changes that are not fully understood. Here, we present results of Doppler imaging (DI) of the rapidly rotating Ap star 56 Ari whose changes in period had previously been detected. A reconstruction of the surface distribution of silicon in 56 Ari reveals its complex spot pattern, which is responsible for the rotationally light variability and is correlated with a magnetic field modulation. Comparisons of abundance maps obtained over the unprecedentedly long (for such studies) interval from 1986 to 2014 confirms the stability and rigid rotation of the spot pattern. Thus, we find the period change in 56 Ari is not caused by a rearrangement of the surface magnetic structures and/or atomic diffusion operating on short timescale. It is also unlikely to be explained by the visibility changes of the spots due to the free-body precession of the stellar rotational axis. We briefly discuss possible alternative explanations of the period variability.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"4 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796404","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202449389
T. Baratashvili, M. Brchnelova, L. Linan, A. Lani, S. Poedts
Solar wind modelling has become a crucial area of study due to the increased dependence of modern society on technology, navigation, and power systems. Accurate space weather forecasts can predict upcoming threats to Earth's geospace and allow for harmful socioeconomic impacts to be mitigated. Coronal and heliospheric models must be as realistic as possible to achieve successful predictions. In this study, we examine a novel full magnetohydrodynamic (MHD) chain from the Sun to Earth. The goal of this study is to demonstrate the capabilities of the full MHD modelling chain from the Sun to Earth by finalising the implementation of the full MHD coronal model into the COolfluid COroNa UnsTructured (COCONUT) model and coupling it to the MHD heliospheric model Icarus. The resulting coronal model has significant advantages compared to the pre-existing polytropic alternative, as it includes more physics and allows for a more realistic modelling of bi-modal wind, which is crucial for heliospheric studies. In particular, we examine different empirical formulations for the heating terms in the MHD equations to determine an optimal one that would be able to mimic a realistic solar wind configuration most accurately. New heating source terms were implemented into the MHD equations of the pre-existing polytropic COCONUT model. A realistic specific heat ratio was applied. In this study, only thermal conduction, radiative losses, and approximated coronal heating function were considered in the energy equation. Multiple approximated heating profiles were examined to see the effect on the solar wind. The output of the coronal model was used to onset the 3D MHD heliospheric model Icarus. A minimum solar activity case was chosen as the first test case for the full MHD model. The numerically simulated data in the corona and the heliosphere were compared to observational products. First, we compared the density data to the available tomography data near the Sun and then the modelled solar wind time series in Icarus was compared to OMNI 1-min data at 1 AU. A range of approximated heating profiles were used in the full MHD coronal model to obtain a realistic solar wind configuration. The bi-modal solar wind was obtained for the corona when introducing heating that is dependent upon the magnetic field. The modelled density profiles are in agreement with the tomography data. The modelled wind in the heliosphere is in reasonable agreement with observations. Overall, the density is overestimated, whereas the speed at 1 AU is more similar to OMNI 1-min data. The general profile of the magnetic field components is modelled well, but its magnitude is underestimated. We present a first attempt to obtain the full MHD chain from the Sun to Earth with COCONUT and Icarus. The coronal model has been upgraded to a full MHD model for a realistic bi-modal solar wind configuration. The approximated heating functions have modelled the wind reasonably well, but simple approximations are n
{"title":"The operationally ready full 3D magnetohydrodynamic model from the Sun to Earth: COCONUT+Icarus","authors":"T. Baratashvili, M. Brchnelova, L. Linan, A. Lani, S. Poedts","doi":"10.1051/0004-6361/202449389","DOIUrl":"https://doi.org/10.1051/0004-6361/202449389","url":null,"abstract":"Solar wind modelling has become a crucial area of study due to the increased dependence of modern society on technology, navigation, and power systems. Accurate space weather forecasts can predict upcoming threats to Earth's geospace and allow for harmful socioeconomic impacts to be mitigated. Coronal and heliospheric models must be as realistic as possible to achieve successful predictions. In this study, we examine a novel full magnetohydrodynamic (MHD) chain from the Sun to Earth. The goal of this study is to demonstrate the capabilities of the full MHD modelling chain from the Sun to Earth by finalising the implementation of the full MHD coronal model into the COolfluid COroNa\u0000UnsTructured (COCONUT) model and coupling it to the MHD heliospheric model Icarus. The resulting coronal model has significant advantages compared to the pre-existing polytropic alternative, as it includes more physics and allows for a more realistic modelling of bi-modal wind, which is crucial for heliospheric studies. In particular, we examine different empirical formulations for the heating terms in the MHD equations to determine an optimal one that would be able to mimic a realistic solar wind configuration most accurately. New heating source terms were implemented into the MHD equations of the pre-existing polytropic COCONUT model. A realistic specific heat ratio was applied. In this study, only thermal conduction, radiative losses, and approximated coronal heating function were considered in the energy equation. Multiple approximated heating profiles were examined to see the effect on the solar wind. The output of the coronal model was used to onset the 3D MHD heliospheric model Icarus. A minimum solar activity case was chosen as the first test case for the full MHD model. The numerically simulated data in the corona and the heliosphere were compared to observational products. First, we compared the density data to the available tomography data near the Sun and then the modelled solar wind time series in Icarus was compared to OMNI 1-min data at 1 AU. A range of approximated heating profiles were used in the full MHD coronal model to obtain a realistic solar wind configuration. The bi-modal solar wind was obtained for the corona when introducing heating that is dependent upon the magnetic field. The modelled density profiles are in agreement with the tomography data. The modelled wind in the heliosphere is in reasonable agreement with observations. Overall, the density is overestimated, whereas the speed at 1 AU is more similar to OMNI 1-min data. The general profile of the magnetic field components is modelled well, but its magnitude is underestimated. We present a first attempt to obtain the full MHD chain from the Sun to Earth with COCONUT and Icarus. The coronal model has been upgraded to a full MHD model for a realistic bi-modal solar wind configuration. The approximated heating functions have modelled the wind reasonably well, but simple approximations are n","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"2 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796713","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202450865
J. Sturm, M. McClure, D. Harsono, J. Bergner, E. Dartois, A. Boogert, M. Cordiner, M. Drozdovskaya, S. Ioppolo, C.J. Law, D. Lis, B. A. McGuire, G. J. Melnick, J. A. Noble, K. Öberg, M. E. Palumbo, Y. Pendleton, G. Perotti, W. Rocha, R. Urso, E. V. van Dishoeck
Ice-coated dust grains provide the main reservoir of volatiles that play an important role in planet formation processes and may become incorporated into planetary atmospheres. However, due to observational challenges, the ice abundance distribution in protoplanetary disks is not well constrained. With the advent of the James Webb Space Telescope (JWST), we are in a unique position to observe these ices in the near- to mid-infrared and constrain their properties in Class II protoplanetary disks. We present JWST Mid-InfraRed Imager (MIRI) observations of the edge-on disk HH 48 NE carried out as part of the Director’s Discretionary Early Release Science program Ice Age, completing the ice inventory of HH 48 NE by combining the MIRI data (5 -- 28 with those of NIRSpec (2.7 -- 5 We used radiative transfer models tailored to the system, including silicates, ices, and polycyclic aromatic hydrocarbons (PAHs) to reproduce the observed spectrum of HH 48 NE with a parameterized model. The model was then used to identify ice species and constrain spatial information about the ices in the disk. The mid-infrared spectrum of HH 48 NE is relatively flat, with weak ice absorption features. We detect CO2 NH3 H2O and tentatively CH4 and NH4+ . Radiative transfer models suggest that ice absorption features are produced predominantly in the 50 -- 100 au region of the disk. The CO2 feature at 15 probes a region closer to the midplane ($z/r$ = 0.1 -- 0.15) than the corresponding feature at 4.3 ($z/r$ = 0.2 -- 0.6), but all observations trace regions significantly above the midplane reservoirs where we expect the bulk of the ice mass to be located. Ices must reach a high scale height ($z/r 0.6$; corresponding to a modeled dust extinction v 0.1$), in order to be consistent with the observed vertical distribution of the peak ice optical depths. The weakness of the CO2 feature at 15 relative to the 4.3 feature and the red emission wing of the 4.3 CO2 feature are both consistent with ices being located at a high elevation in the disk. The retrieved NH3 abundance and the upper limit on the CH3OH abundance relative to H2O are significantly lower than those in the interstellar medium, but consistent with cometary observations. The contrast of the PAH emission features with the continuum is stronger than for similar face-on protoplanetary disks, which is likely a result of the edge-on system geometry. Modeling based on the relative strength of the emission features suggests that the PAH emission originates in the disk surface layer rather than the ice absorbing layer. Full wavelength coverage is required to properly study the abundance distribution of ices in disks. To explain the presence of ices at high disk altitudes, we propose two possible scenarios: a disk wind that entrains sufficient amounts of dust, and thus blocks part of the stellar UV radiation, or vertical mixing that cycles enough ices into the upper disk layers to balance ice photodesorption from t
冰涂层尘粒是挥发物的主要储藏库，在行星形成过程中发挥着重要作用，并可能融入行星大气。 然而，由于观测方面的挑战，原行星盘中的冰丰度分布并没有得到很好的约束。 随着詹姆斯-韦伯太空望远镜（JWST）的问世，我们处于一个独特的位置，可以用近红外到中红外光谱观测这些冰，并对它们在II类原系星盘中的性质进行约束。我们展示了JWST中红外成像仪（MIRI）对边缘盘HH 48 NE的观测结果，这是 "冰河时代"（Ice Age）主任酌情早期发布科学计划的一部分，通过将MIRI数据（5--28）与NIRSpec数据（2.7--5）相结合，完成了HH 48 NE的冰清单。 我们使用了针对该系统量身定制的辐射传递模型，包括硅酸盐、冰和多环芳烃（PAHs），用参数化模型重现了HH 48 NE的观测光谱。 然后利用该模型来识别冰的种类，并对圆盘中冰的空间信息进行约束。HH 48 NE 的中红外光谱相对平坦，具有微弱的冰吸收特征。 我们探测到了 CO2 NH3 H2O，并初步探测到了 CH4 和 NH4+。辐射传递模型表明，冰吸收特征主要产生于磁盘的 50-100 au 区域。与 4.3 处的相应特征（$z/r$ = 0.2-0.6）相比，15 处的 CO2 特征探测的区域更接近中面（$z/r$ = 0.1-0.15），但所有观测都追踪了明显高于中面储层的区域，我们预计大部分冰体都位于中面储层。冰必须达到较高的尺度高度（$z/r 0.6$；对应于模型尘埃消光 v 0.1$），才能与观测到的冰光学深度峰值的垂直分布相一致。相对于 4.3 特征，15 点的 CO2 特征较弱，而且 4.3 CO2 特征的红色发射翼与冰位于星盘高处的情况一致。检索到的 NH3 丰度和相对于 H2O 的 CH3OH 丰度上限明显低于星际介质，但与彗星观测结果一致。多环芳烃的发射特征与连续面的对比比类似的面朝上的原行星盘更强烈，这可能是边缘系统几何形状的结果。 根据发射特征的相对强度建立的模型表明，PAH 发射源于盘表层而非冰吸收层。要正确研究盘中冰的丰度分布，就必须覆盖全部波长。为了解释在磁盘高空出现冰的原因，我们提出了两种可能的情况：一种是磁盘风夹带了足够多的尘埃，从而阻挡了部分恒星紫外线辐射；另一种是垂直混合，使足够多的冰循环到磁盘上层，以平衡冰粒的光吸收。
{"title":"A JWST/MIRI analysis of the ice distribution and polycyclic aromatic hydrocarbon emission in the protoplanetary disk HH 48 NE","authors":"J. Sturm, M. McClure, D. Harsono, J. Bergner, E. Dartois, A. Boogert, M. Cordiner, M. Drozdovskaya, S. Ioppolo, C.J. Law, D. Lis, B. A. McGuire, G. J. Melnick, J. A. Noble, K. Öberg, M. E. Palumbo, Y. Pendleton, G. Perotti, W. Rocha, R. Urso, E. V. van Dishoeck","doi":"10.1051/0004-6361/202450865","DOIUrl":"https://doi.org/10.1051/0004-6361/202450865","url":null,"abstract":"Ice-coated dust grains provide the main reservoir of volatiles that play an important role in planet formation processes and may become incorporated into planetary atmospheres. \u0000 However, due to observational challenges, the ice abundance distribution in protoplanetary disks is not well constrained. \u0000 With the advent of the James Webb Space Telescope (JWST), we are in a unique position to observe these ices in the near- to mid-infrared and constrain their properties in Class II protoplanetary disks. We present JWST Mid-InfraRed Imager (MIRI) observations of the edge-on disk HH 48 NE carried out as part of the Director’s Discretionary Early Release Science program Ice Age, completing the ice inventory of HH 48 NE by combining the MIRI data (5 -- 28 with those of NIRSpec (2.7 -- 5 We used radiative transfer models tailored to the system, including silicates, ices, and polycyclic aromatic hydrocarbons (PAHs) to reproduce the observed spectrum of HH 48 NE with a parameterized model. \u0000 The model was then used to identify ice species and constrain spatial information about the ices in the disk. The mid-infrared spectrum of HH 48 NE is relatively flat, with weak ice absorption features. \u0000 We detect CO2 NH3 H2O and tentatively CH4 and NH4+ .\u0000 Radiative transfer models suggest that ice absorption features are produced predominantly in the 50 -- 100 au region of the disk. The CO2 feature at 15 probes a region closer to the midplane ($z/r$ = 0.1 -- 0.15) than the corresponding feature at 4.3 ($z/r$ = 0.2 -- 0.6), but all observations trace regions significantly above the midplane reservoirs where we expect the bulk of the ice mass to be located. Ices must reach a high scale height ($z/r 0.6$; corresponding to a modeled dust extinction v 0.1$), in order to be consistent with the observed vertical distribution of the peak ice optical depths. The weakness of the CO2 feature at 15 relative to the 4.3 feature and the red emission wing of the 4.3 CO2 feature are both consistent with ices being located at a high elevation in the disk.\u0000 The retrieved NH3 abundance and the upper limit on the CH3OH abundance relative to H2O are significantly lower than those in the interstellar medium, but consistent with cometary observations.\u0000 The contrast of the PAH emission features with the continuum is stronger than for similar face-on protoplanetary disks, which is likely a result of the edge-on system geometry. \u0000 Modeling based on the relative strength of the emission features suggests that the PAH emission originates in the disk surface layer rather than the ice absorbing layer. Full wavelength coverage is required to properly study the abundance distribution of ices in disks.\u0000 To explain the presence of ices at high disk altitudes, we propose two possible scenarios: a disk wind that entrains sufficient amounts of dust, and thus blocks part of the stellar UV radiation, or vertical mixing that cycles enough ices into the upper disk layers to balance ice photodesorption from t","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"2 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796538","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202450971
V. Braga, M. Monelli, M. Dall’ora, J.P. Mullen, R. Molinaro, M. Marconi, R. Szabo, C. Gallart
The Vera C. Rubin Observatory will start operations in 2025. During its first two years, too few visits per target per band will be available, meaning that the mean magnitude measurements of variable stars will not be precise and thus standard candles such as RR Lyrae (RRL) will not be usable. Light curve templates (LCTs) can be adopted to estimate the mean magnitude of a variable star with a few magnitude measurements, provided that their period (plus the amplitude and reference epoch, depending on how the LCT is applied) is known. The LSST will provide precise RRL periods within the first six months, enabling exploitation of RRLs if LCTs are available. We aim to build LCTs in the LSST bands to enhance the early science with LSST. Using them will provide a one- to two-year advantage with respect to the classical approach concerning distance measurements. We collected $gri$-band data from the ZTF survey and $z$-band data from DECam to build the LCTs of RRLs. We also adopted synthetic $griz$ band data in the LSST system from pulsation models, plus SDSS and OGLE photometry, inspecting the light amplitude ratios in different photometric systems to provide useful conversions to apply the LCTs. We have built LCTs of RRLs in the $griz$ bands of the LSST photometric system; for the $z$ band, we could build only fundamental mode RRL LCTs. We quantitatively demonstrated that LCTs built with ZTF and DECam data can be adopted on the LSST photometric system. The LCTs will decrease the uncertainty on distance estimates of RRLs by a factor of at least two with respect to a simple average of the available measurements. Finally, within our tests, we have found a brand new behavior of amplitude ratios in the Large Magellanic Cloud.
{"title":"On the use of field RR Lyrae as Galactic probes VII. Light curve templates in the LSST photometric system","authors":"V. Braga, M. Monelli, M. Dall’ora, J.P. Mullen, R. Molinaro, M. Marconi, R. Szabo, C. Gallart","doi":"10.1051/0004-6361/202450971","DOIUrl":"https://doi.org/10.1051/0004-6361/202450971","url":null,"abstract":"The Vera C. Rubin Observatory will start operations in 2025. During its first two years, too few visits per target per band will be available, meaning that the mean magnitude measurements of variable stars will not be precise and thus standard candles such as RR Lyrae (RRL) will not be usable. Light curve templates (LCTs) can be adopted to estimate the mean magnitude of a variable star with a few magnitude measurements, provided that their period (plus the amplitude and reference epoch, depending on how the LCT is applied) is known. The LSST will provide precise RRL periods within the first six months, enabling exploitation of RRLs if LCTs are available. We aim to build LCTs in the LSST bands to enhance the early science with LSST. Using them will provide a one- to two-year advantage with respect to the classical approach concerning distance measurements. We collected $gri$-band data from the ZTF survey and $z$-band data from DECam to build the LCTs of RRLs. We also adopted synthetic $griz$ band data in the LSST system from pulsation models, plus SDSS and OGLE photometry, inspecting the light amplitude ratios in different photometric systems to provide useful conversions to apply the LCTs. We have built LCTs of RRLs in the $griz$ bands of the LSST photometric system; for the $z$ band, we could build only fundamental mode RRL LCTs. We quantitatively demonstrated that LCTs built with ZTF and DECam data can be adopted on the LSST photometric system. The LCTs will decrease the uncertainty on distance estimates of RRLs by a factor of at least two with respect to a simple average of the available measurements. Finally, within our tests, we have found a brand new behavior of amplitude ratios in the Large Magellanic Cloud.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"12 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796335","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}
Pub Date : 2024-07-29DOI: 10.1051/0004-6361/202451245
A. Tarchi, P. Castangia, G. Surcis, V. Impellizzeri, E. Ladu, E. Yu Bannikova
The low-ionization nuclear emission-line region (LINER) galaxy TXS,2226-184 is known to host a very luminous 22 GHz water maser, called a gigamaser at the time of its discovery. To date, the nature of this maser is still being debated, in particular, whether it is associated with a nuclear accretion disk or with an ejection component, namely a jet or an outflow originating in the active galactic nucleus. We obtained multi-band (bands 5, 6, and 7) ALMA observations during Cycle 9, with the purpose of investigating the maser nature and the nuclear molecular material in the innermost region of the galaxy. While the full data sets are still under study, a preliminary data reduction and analysis of the band 5 and 7 spectral line cubes presented in this Letter already offer a significant outcome. We observed bright, possibly maser emission from the water 183 GHz and 380 GHz transitions in TXS,2226-184. To the best of our knowledge, this represents the first unambiguous detection (S/N ge 100) of 380 GHz maser emission in a known 22-GHz maser galaxy, and the first case where all three transitions are present in the same object. Emission features at both frequencies show a two-peaked line profile resembling that of the 22 GHz maser features. The millimeter/submillimeter emission originates from a region coincident, within the errors, with that of the 22 GHz. The similarities in profile and position indicate that the emission at the three frequencies is likely produced by the same nuclear structure, although differences in line strengths and feature peak positions may hint at a slightly different physical conditions of the emitting gas. A comparison with the few megamaser sources studied at high enough detail and sharing similarities with the water lines in TXS,2226-184 favors a nature associated with the amplification of a bright nuclear continuum (from a jet or outflow) through dense and hot gas in front of the nucleus (e.g., a disk or torus); however, a more comprehensive analysis of the available data is necessary to better assess this scenario.
{"title":"Detection of maser emission at 183 and 380 GHz with ALMA in the gigamaser galaxy TX 2226-184","authors":"A. Tarchi, P. Castangia, G. Surcis, V. Impellizzeri, E. Ladu, E. Yu Bannikova","doi":"10.1051/0004-6361/202451245","DOIUrl":"https://doi.org/10.1051/0004-6361/202451245","url":null,"abstract":"The low-ionization nuclear emission-line region (LINER) galaxy TXS,2226-184 is known to host a very luminous 22 GHz water maser, called a gigamaser at the time of its discovery. To date, the nature of this maser is still being debated, in particular, whether it is associated with a nuclear accretion disk or with an ejection component, namely a jet or an outflow originating in the active galactic nucleus. We obtained multi-band (bands 5, 6, and 7) ALMA observations during Cycle 9, with the purpose of investigating the maser nature and the nuclear molecular material in the innermost region of the galaxy. While the full data sets are still under study, a preliminary data reduction and analysis of the band 5 and 7 spectral line cubes presented in this Letter already offer a significant outcome. We observed bright, possibly maser emission from the water 183 GHz and 380 GHz transitions in TXS,2226-184. To the best of our knowledge, this represents the first unambiguous detection (S/N ge 100) of 380 GHz maser emission in a known 22-GHz maser galaxy, and the first case where all three transitions are present in the same object. Emission features at both frequencies show a two-peaked line profile resembling that of the 22 GHz maser features. The millimeter/submillimeter emission originates from a region coincident, within the errors, with that of the 22 GHz. The similarities in profile and position indicate that the emission at the three frequencies is likely produced by the same nuclear structure, although differences in line strengths and feature peak positions may hint at a slightly different physical conditions of the emitting gas. A comparison with the few megamaser sources studied at high enough detail and sharing similarities with the water lines in TXS,2226-184 favors a nature associated with the amplification of a bright nuclear continuum (from a jet or outflow) through dense and hot gas in front of the nucleus (e.g., a disk or torus); however, a more comprehensive analysis of the available data is necessary to better assess this scenario.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"3 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141796532","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：