Pub Date : 2025-02-18DOI: 10.1051/0004-6361/202451994
L. M. Bernabò, Sz. Csizmadia, A. M. S. Smith, J.-V. Harre, Sz. Kálmán, J. Cabrera, H. Rauer, D. Gandolfi, L. Pino, D. Ehrenreich, A. Hatzes
Context. Recent developments in exoplanetary research highlight the importance of Love numbers in understanding the internal dynamics, formation, migration history, and potential habitability of exoplanets. Love numbers represent crucial parameters that gauge how exoplanets respond to external forces such as tidal interactions and rotational effects. By measuring these responses, insights into the internal structure, composition, and density distribution of exoplanets can be gained. The rate of apsidal precession of a planetary orbit is directly linked to the second-order fluid Love numbers. Thus, Love numbers can also offer valuable insights into the mass distribution of a planet.Aims. In this context, we aim to re-determine the orbital parameters of WASP-43b – in particular, the orbital period, eccentricity, and argument of the periastron – and its orbital evolution. We study the outcomes of the tidal interaction with the host star in order to identify whether tidal decay and periastron precession occur in the system.Methods. We observed WASP-43b with HARPS, whose data we present for the first time, and we also analysed the newly acquired JWST full-phase light curve. We jointly fit new and archival radial velocity and transit and occultation mid-times, including tidal decay, periastron precession, and long-term acceleration in the system.Results. We detected a tidal decay rate of Ṗa = (−l.99±0.50) ms yr−1 and a periastron precession rate of )° . This is the first time that both periastron precession and tidal decay are simultaneously detected in an exoplanetary system. The observed tidal interactions can neither be explained by the tidal contribution to apsidal motion of a non-aligned stellar or planetary rotation axis nor by assuming a non-synchronous rotation for the planet, and a value for the planetary Love number cannot be derived. Moreover, we excluded the presence of a second body (e.g. a distant companion star or a yet undiscovered planet) down to a planetary mass of ≳0.3 MJ and up to an orbital period of ≲3700 days. We leave the question of the cause of the observed apsidal motion open.
{"title":"Characterising WASP-43b’s interior structure: Unveiling tidal decay and apsidal motion","authors":"L. M. Bernabò, Sz. Csizmadia, A. M. S. Smith, J.-V. Harre, Sz. Kálmán, J. Cabrera, H. Rauer, D. Gandolfi, L. Pino, D. Ehrenreich, A. Hatzes","doi":"10.1051/0004-6361/202451994","DOIUrl":"https://doi.org/10.1051/0004-6361/202451994","url":null,"abstract":"<i>Context<i/>. Recent developments in exoplanetary research highlight the importance of Love numbers in understanding the internal dynamics, formation, migration history, and potential habitability of exoplanets. Love numbers represent crucial parameters that gauge how exoplanets respond to external forces such as tidal interactions and rotational effects. By measuring these responses, insights into the internal structure, composition, and density distribution of exoplanets can be gained. The rate of apsidal precession of a planetary orbit is directly linked to the second-order fluid Love numbers. Thus, Love numbers can also offer valuable insights into the mass distribution of a planet.<i>Aims<i/>. In this context, we aim to re-determine the orbital parameters of WASP-43b – in particular, the orbital period, eccentricity, and argument of the periastron – and its orbital evolution. We study the outcomes of the tidal interaction with the host star in order to identify whether tidal decay and periastron precession occur in the system.<i>Methods<i/>. We observed WASP-43b with HARPS, whose data we present for the first time, and we also analysed the newly acquired JWST full-phase light curve. We jointly fit new and archival radial velocity and transit and occultation mid-times, including tidal decay, periastron precession, and long-term acceleration in the system.<i>Results<i/>. We detected a tidal decay rate of <i>Ṗ<i/><sub><i>a<i/><sub/> = (−l.99±0.50) ms yr<sup>−1<sup/> and a periastron precession rate of )° . This is the first time that both periastron precession and tidal decay are simultaneously detected in an exoplanetary system. The observed tidal interactions can neither be explained by the tidal contribution to apsidal motion of a non-aligned stellar or planetary rotation axis nor by assuming a non-synchronous rotation for the planet, and a value for the planetary Love number cannot be derived. Moreover, we excluded the presence of a second body (e.g. a distant companion star or a yet undiscovered planet) down to a planetary mass of ≳0.3 <i>M<i/><sub><i>J<i/><sub/> and up to an orbital period of ≲3700 days. We leave the question of the cause of the observed apsidal motion open.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"80 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435771","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 : 2025-02-18DOI: 10.1051/0004-6361/202453221
V. Hocdé, T. Kamiński, M. Lewis, N. Nardetto, P. Kervella, G. Pietrzyński
Cepheid circumstellar emissions have previously been detected using both infrared (IR) excess and IR interferometric observations at a few stellar radii. These studies have shown that these circumstellar emission can be produced by ionized gas, however, there is no direct observational evidence to confirm this hypothesis. In this letter, we explore the continuum emission and a spectrum of the bright and long-period Cepheid ℓ Car (P = 35.56 day) at millimeter-wavelengths to detect possible effects of ionized gas emission. We used ALMA observations of ℓ Car in two spectral setups in Band 6 (near 212 and 253 GHz, respectively) and compared the measured flux density to what would be expected for the stellar continuum. We also derived the spectral index and probed the presence of radio recombination lines (RRLs). We report statistically significant emission of about 3.5 mJy in the two spectral ranges, which is about 2.5 times the stellar continuum emission. For the first time, we have also been able to derive the spectral index of the flux density, (Sν ∝ να), α = +1.26 ± 0.44 (∼3σ error), which is characteristic of partially optically thick, ionized gas emission. Additionally, we discovered an emission line from a RRL of hydrogen H29α centered on the stellar rest velocity, smaller in spatial extent than about 0″.2 (≲100 AU), with a symmetric profile with a width at half power of 55.3 ± 7.5 km s−1 (1σ error). These findings confirm the presence of ionized gas emission near ℓ Car. The millimeter emission detected from ℓ Car can be attributed to ionized gas emission from the Cepheid’s chromosphere. Further radio interferometric observations are necessary to confirm the occurrence of these ionized gas envelopes around Cepheids of different pulsation periods.
{"title":"Discovery of ionized circumstellar gas emission around the long-period Cepheid ℓ Carinae with ALMA","authors":"V. Hocdé, T. Kamiński, M. Lewis, N. Nardetto, P. Kervella, G. Pietrzyński","doi":"10.1051/0004-6361/202453221","DOIUrl":"https://doi.org/10.1051/0004-6361/202453221","url":null,"abstract":"Cepheid circumstellar emissions have previously been detected using both infrared (IR) excess and IR interferometric observations at a few stellar radii. These studies have shown that these circumstellar emission can be produced by ionized gas, however, there is no direct observational evidence to confirm this hypothesis. In this letter, we explore the continuum emission and a spectrum of the bright and long-period Cepheid <i>ℓ<i/> Car (<i>P<i/> = 35.56 day) at millimeter-wavelengths to detect possible effects of ionized gas emission. We used ALMA observations of <i>ℓ<i/> Car in two spectral setups in Band 6 (near 212 and 253 GHz, respectively) and compared the measured flux density to what would be expected for the stellar continuum. We also derived the spectral index and probed the presence of radio recombination lines (RRLs). We report statistically significant emission of about 3.5 mJy in the two spectral ranges, which is about 2.5 times the stellar continuum emission. For the first time, we have also been able to derive the spectral index of the flux density, (<i>S<i/><sub><i>ν<i/><sub/> ∝ <i>ν<i/><sup><i>α<i/><sup/>), <i>α<i/> = +1.26 ± 0.44 (∼3<i>σ<i/> error), which is characteristic of partially optically thick, ionized gas emission. Additionally, we discovered an emission line from a RRL of hydrogen H29<i>α<i/> centered on the stellar rest velocity, smaller in spatial extent than about 0″.2 (≲100 AU), with a symmetric profile with a width at half power of 55.3 ± 7.5 km s<sup>−1<sup/> (1<i>σ<i/> error). These findings confirm the presence of ionized gas emission near <i>ℓ<i/> Car. The millimeter emission detected from <i>ℓ<i/> Car can be attributed to ionized gas emission from the Cepheid’s chromosphere. Further radio interferometric observations are necessary to confirm the occurrence of these ionized gas envelopes around Cepheids of different pulsation periods.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435710","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 : 2025-02-18DOI: 10.1051/0004-6361/202453400
Lientur Celedón, Claus Tappert, Linda Schmidtobreick, Fernando J. Selman
Context. Nova shells are the remnants of a nova eruption in a cataclysmic variable system. By studying their geometry we can better understand the physical mechanisms that shape such shells during the nova eruption. A nova shell that challenges our current understanding of these processes is the shell observed around V1425 Aql. It has at least two different components: an inner, symmetric shell and an outer, asymmetric shell, with the latter expanding faster than the former. The physical reason for the asymmetric ejecta is not clear.Aims. We aim to characterise the properties of and differences between these two components to understand the origin of the unusual shape.Methods. We acquired MUSE data to study the spatial position and kinematics of the expanding gas across the shell. Our analysis involved channel maps, position-velocity diagrams, and the reconstruction of the 3D geometry of the nova shell.Results. Several emission lines are detected within the MUSE wavelength coverage, including but not limited to Balmer, oxygen, nitrogen, and helium lines. There are significant differences in the spectra of the inner and outer shells, with the latter being observed only in forbidden transitions, and the former in a mix of forbidden and allowed ones. Our analysis reveals that the outer shell has a geometry consistent with an arc-shaped structure that partially encircles the more spherical inner shell. Within the inner shell, clumpy structures start to be noticeable in the lines of Hα+[N II].Conclusions. We have constrained the geometry of the outer shell to an arc-shaped structure, although the physical reason for its origin still eludes us. Further monitoring of the evolution of both shells of this object might help clarify the mechanism behind this unusual configuration.
{"title":"MUSE observations of V1425 Aql reveal an arc-shaped nova shell","authors":"Lientur Celedón, Claus Tappert, Linda Schmidtobreick, Fernando J. Selman","doi":"10.1051/0004-6361/202453400","DOIUrl":"https://doi.org/10.1051/0004-6361/202453400","url":null,"abstract":"<i>Context<i/>. Nova shells are the remnants of a nova eruption in a cataclysmic variable system. By studying their geometry we can better understand the physical mechanisms that shape such shells during the nova eruption. A nova shell that challenges our current understanding of these processes is the shell observed around V1425 Aql. It has at least two different components: an inner, symmetric shell and an outer, asymmetric shell, with the latter expanding faster than the former. The physical reason for the asymmetric ejecta is not clear.<i>Aims<i/>. We aim to characterise the properties of and differences between these two components to understand the origin of the unusual shape.<i>Methods<i/>. We acquired MUSE data to study the spatial position and kinematics of the expanding gas across the shell. Our analysis involved channel maps, position-velocity diagrams, and the reconstruction of the 3D geometry of the nova shell.<i>Results<i/>. Several emission lines are detected within the MUSE wavelength coverage, including but not limited to Balmer, oxygen, nitrogen, and helium lines. There are significant differences in the spectra of the inner and outer shells, with the latter being observed only in forbidden transitions, and the former in a mix of forbidden and allowed ones. Our analysis reveals that the outer shell has a geometry consistent with an arc-shaped structure that partially encircles the more spherical inner shell. Within the inner shell, clumpy structures start to be noticeable in the lines of H<i>α<i/>+[N II].<i>Conclusions<i/>. We have constrained the geometry of the outer shell to an arc-shaped structure, although the physical reason for its origin still eludes us. Further monitoring of the evolution of both shells of this object might help clarify the mechanism behind this unusual configuration.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435714","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 : 2025-02-18DOI: 10.1051/0004-6361/202453302
Dhanraj Risbud, Vikrant V. Jadhav, Pavel Kroupa
Context. Tidal tails of open clusters are the result of stellar evaporation from the cluster through the Galactic potential and internal dynamics. With the recent availability of high-precision data, tidal tails are being detected for most of the nearby open clusters.Aims. We identify the tidal tail members for all open clusters within a distance of 400 pc that are older than 100 Myr and have >100 members. To do this, we use model-independent methods.Methods. We used the convergent-point (CP) method to identify the co-moving stars near the open clusters using Gaia DR3 data. A new method called the self-compact convergent-point method was proposed and applied to some of the clusters. It performed better overall in tracing the tails. We also analysed the colour-magnitude diagrams and orbital energy to diagnose possible contamination.Results. Nineteen out of 21 clusters have tidal tails. Five of them were discovered for the first time through this work. The typical span of the tidal tails is 20–200 pc, and 30–700 member stars lie in the region inside the tidal radius and the tidal tails. Four out of 19 tidal tails are tilted away from direction of the Galactic centre. This contradicts the known theory of the tidal-tail formation. The luminosity functions of the tails and clusters are consistent with each other and with the canonical stellar interstellar mass function, but systematically higher radial velocities for the trailing tail than for the leading tail were observed for the first time.Conclusions. The CP method is useful for detecting tidal tails on a scale of ≈100 pc for clusters closer than 400 pc. A further analysis of theoretical N-body models is required to understand the incompleteness and biases in the current sample of tidal tails.
{"title":"Tidal tails of nearby open clusters","authors":"Dhanraj Risbud, Vikrant V. Jadhav, Pavel Kroupa","doi":"10.1051/0004-6361/202453302","DOIUrl":"https://doi.org/10.1051/0004-6361/202453302","url":null,"abstract":"<i>Context<i/>. Tidal tails of open clusters are the result of stellar evaporation from the cluster through the Galactic potential and internal dynamics. With the recent availability of high-precision data, tidal tails are being detected for most of the nearby open clusters.<i>Aims<i/>. We identify the tidal tail members for all open clusters within a distance of 400 pc that are older than 100 Myr and have >100 members. To do this, we use model-independent methods.<i>Methods<i/>. We used the convergent-point (CP) method to identify the co-moving stars near the open clusters using <i>Gaia<i/> DR3 data. A new method called the self-compact convergent-point method was proposed and applied to some of the clusters. It performed better overall in tracing the tails. We also analysed the colour-magnitude diagrams and orbital energy to diagnose possible contamination.<i>Results<i/>. Nineteen out of 21 clusters have tidal tails. Five of them were discovered for the first time through this work. The typical span of the tidal tails is 20–200 pc, and 30–700 member stars lie in the region inside the tidal radius and the tidal tails. Four out of 19 tidal tails are tilted away from direction of the Galactic centre. This contradicts the known theory of the tidal-tail formation. The luminosity functions of the tails and clusters are consistent with each other and with the canonical stellar interstellar mass function, but systematically higher radial velocities for the trailing tail than for the leading tail were observed for the first time.<i>Conclusions<i/>. The CP method is useful for detecting tidal tails on a scale of ≈100 pc for clusters closer than 400 pc. A further analysis of theoretical <i>N<i/>-body models is required to understand the incompleteness and biases in the current sample of tidal tails.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435735","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 : 2025-02-18DOI: 10.1051/0004-6361/202452985
I. Kraus, Ph.-A. Bourdin, J. Zender, M. Bergmann, A. Hanslmeier
Context. The solar corona maintains temperatures of a million Kelvin or more. The plasma heating mechanisms responsible for these extreme temperatures are still unclear. Large regions of magnetic activity in the photosphere cause extreme ultraviolet (EUV) emission in the corona. Even smaller regions with bipolar and multipolar magnetic fields can generate coronal bright points (CBPs).Aims. We performed a statistical analysis of 346 CBPs. We used Solar Dynamics Observatory (SDO) images to track CBPs on a continuous basis. Therefore, we were able to collect a database of information on the CPB’s lifetime, shape, polarity, flux emergence, and merging behavior, as well as their magnetic evolution, using the SDO Helioseismic and Magnetic Imager (SDO-HMI) instrument.Methods. We searched the SDO data archive for the longest continuous interval of uninterrupted observations in 2015. The longest such interval contains 12 consecutive days of full-disk images from the EUV channels of the SDO-AIA instrument. To analyze the properties of CBPs, we employed an automated tracking algorithm to follow the evolution of the CBPs. Furthermore, we manually checked the shape, underlying magnetic polarities, and merging behavior of each CBP.Results. We provide statistics on the magnetic polarity, emergence, and merging of CBPs. We established a relationship between the CBP’s merging behavior and both its shape and magnetic polarities. Brighter CBPs are visible in all SDO-AIA channels and exhibit strong radiative energy losses. The category of CBPs with a bipolar field has the highest probability of being emissive in all SDO-AIA channels. The majority of CBPs have two opposite polarities below them.Conclusions. The merging of two CBPs is an unusual phenomenon that is related to complex multipolar magnetic regions. Moreover, loop-shaped CBPs usually appear above bipolar fields. Faint CBPs have shorter lifetimes and are less likely to merge with another CBP.
{"title":"Coronal bright point statistics","authors":"I. Kraus, Ph.-A. Bourdin, J. Zender, M. Bergmann, A. Hanslmeier","doi":"10.1051/0004-6361/202452985","DOIUrl":"https://doi.org/10.1051/0004-6361/202452985","url":null,"abstract":"<i>Context.<i/> The solar corona maintains temperatures of a million Kelvin or more. The plasma heating mechanisms responsible for these extreme temperatures are still unclear. Large regions of magnetic activity in the photosphere cause extreme ultraviolet (EUV) emission in the corona. Even smaller regions with bipolar and multipolar magnetic fields can generate coronal bright points (CBPs).<i>Aims.<i/> We performed a statistical analysis of 346 CBPs. We used Solar Dynamics Observatory (SDO) images to track CBPs on a continuous basis. Therefore, we were able to collect a database of information on the CPB’s lifetime, shape, polarity, flux emergence, and merging behavior, as well as their magnetic evolution, using the SDO Helioseismic and Magnetic Imager (SDO-HMI) instrument.<i>Methods.<i/> We searched the SDO data archive for the longest continuous interval of uninterrupted observations in 2015. The longest such interval contains 12 consecutive days of full-disk images from the EUV channels of the SDO-AIA instrument. To analyze the properties of CBPs, we employed an automated tracking algorithm to follow the evolution of the CBPs. Furthermore, we manually checked the shape, underlying magnetic polarities, and merging behavior of each CBP.<i>Results.<i/> We provide statistics on the magnetic polarity, emergence, and merging of CBPs. We established a relationship between the CBP’s merging behavior and both its shape and magnetic polarities. Brighter CBPs are visible in all SDO-AIA channels and exhibit strong radiative energy losses. The category of CBPs with a bipolar field has the highest probability of being emissive in all SDO-AIA channels. The majority of CBPs have two opposite polarities below them.<i>Conclusions.<i/> The merging of two CBPs is an unusual phenomenon that is related to complex multipolar magnetic regions. Moreover, loop-shaped CBPs usually appear above bipolar fields. Faint CBPs have shorter lifetimes and are less likely to merge with another CBP.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435774","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 : 2025-02-14DOI: 10.1051/0004-6361/202452416
Yadi Yang, Xi Luo, Xiaojian Song, Weiwei Xu, Marius S. Potgieter
Aims. Alpha Magnetic Spectrometer (AMS), installed on the International Space Station, delivers precision measurements of cosmic proton fluxes and electron fluxes, providing unique inputs to further improve our understanding of the solar modulation of cosmic protons and electrons. The latest measurements published by AMS show significant decreases in daily cosmic proton fluxes and electron fluxes in the second half of 2017 (approximately from June 11, 2017 to December 23, 2017). A special structure, known as a loop, appears in the electron-proton hysteresis during this period. These declining fluxes, as well as their recovery toward solar minimum modulation, could be attributed to solar wind structures such as global merged interaction regions (GMIRs), which can affect cosmic ray flux for several months, as well as coronal mass ejections (CMEs). We aim to find the reason for the decrease and clarify the solar modulation mechanism underlying the loop structure.Methods. We developed a 3D numerical model based on Parker transport equation, which is solved as a set of stochastic differential equations, combined with diffusion barriers propagating away from the Sun. Correspondingly, the relevant parameters can be tuned up.Results. The unusual changes in cosmic proton fluxes and electron fluxes in the second half of 2017 could be caused by CMEs and GMIRs. The decreases in these fluxes in 2017, with rigidities below 11 GV, have been successfully reproduced. Daily variations at Earth in terms of the diffusion coefficients (and their mean-free paths) were subsequently obtained. Furthermore, our simulation reveals that the electron-proton hysteresis loop structure in 2017 results from the different responses of protons and electrons to solar modulation, especially with respect to drift and diffusion processes in the heliosphere.
{"title":"A numerical study of unusual flux decreases for cosmic ray protons and electrons observed by Alpha Magnetic Spectrometer in 2017","authors":"Yadi Yang, Xi Luo, Xiaojian Song, Weiwei Xu, Marius S. Potgieter","doi":"10.1051/0004-6361/202452416","DOIUrl":"https://doi.org/10.1051/0004-6361/202452416","url":null,"abstract":"<i>Aims.<i/> Alpha Magnetic Spectrometer (AMS), installed on the International Space Station, delivers precision measurements of cosmic proton fluxes and electron fluxes, providing unique inputs to further improve our understanding of the solar modulation of cosmic protons and electrons. The latest measurements published by AMS show significant decreases in daily cosmic proton fluxes and electron fluxes in the second half of 2017 (approximately from June 11, 2017 to December 23, 2017). A special structure, known as a loop, appears in the electron-proton hysteresis during this period. These declining fluxes, as well as their recovery toward solar minimum modulation, could be attributed to solar wind structures such as global merged interaction regions (GMIRs), which can affect cosmic ray flux for several months, as well as coronal mass ejections (CMEs). We aim to find the reason for the decrease and clarify the solar modulation mechanism underlying the loop structure.<i>Methods.<i/> We developed a 3D numerical model based on Parker transport equation, which is solved as a set of stochastic differential equations, combined with diffusion barriers propagating away from the Sun. Correspondingly, the relevant parameters can be tuned up.<i>Results.<i/> The unusual changes in cosmic proton fluxes and electron fluxes in the second half of 2017 could be caused by CMEs and GMIRs. The decreases in these fluxes in 2017, with rigidities below 11 GV, have been successfully reproduced. Daily variations at Earth in terms of the diffusion coefficients (and their mean-free paths) were subsequently obtained. Furthermore, our simulation reveals that the electron-proton hysteresis loop structure in 2017 results from the different responses of protons and electrons to solar modulation, especially with respect to drift and diffusion processes in the heliosphere.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427443","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 : 2025-02-14DOI: 10.1051/0004-6361/202452526
Juris Kalvāns
Context. Matter that falls onto a protoplanetary disk (PPD) from a protostellar envelope is heated before it cools again. This induces sublimation and subsequent re-adsorption of ices that accumulated during the prestellar phase.Aims. We explore the fate of ices on multiple-sized dust grains in a parcel of infalling matter.Methods. A comprehensive kinetic chemical model using five grain-size bins with different temperatures was applied for an infalling parcel. The parcel was heated to 150 K and then cooled over a total timescale of 20 kyr. Effects on ice loss and re-accumulation by the changed gas density, the maximum temperature, the irradiation intensity, the size-dependent grain temperature trend, and the distribution of the ice mass among the grain-size bins were investigated.Results. A massive selective redistribution of ices exclusively onto the surface of the coldest grain-size bin occurs in all models. The redistribution starts already during the heating stage, where ices that are sublimated from warmer grains re-adsorb onto colder grains before complete sublimation. During the cooling stage, the sublimated molecules re-freeze again onto the coldest grains. In the case of full sublimation, this re-adsorption is delayed and occurs at lower temperatures because a bare grain surface has lower molecular desorption energies in our model.Conclusions. Most protostellar envelope grains enter the PPD ice poor (bare). Ices are carried by a single coldest grain-size bin, here representing 12% of the total grain surface area. This bare ice-grain dualism can affect the rate of the grain coagulation. The ice components are stratified on the grains according to their sublimation temperatures.
{"title":"Redistribution of ices between grain populations in protostellar envelopes","authors":"Juris Kalvāns","doi":"10.1051/0004-6361/202452526","DOIUrl":"https://doi.org/10.1051/0004-6361/202452526","url":null,"abstract":"<i>Context<i/>. Matter that falls onto a protoplanetary disk (PPD) from a protostellar envelope is heated before it cools again. This induces sublimation and subsequent re-adsorption of ices that accumulated during the prestellar phase.<i>Aims<i/>. We explore the fate of ices on multiple-sized dust grains in a parcel of infalling matter.<i>Methods<i/>. A comprehensive kinetic chemical model using five grain-size bins with different temperatures was applied for an infalling parcel. The parcel was heated to 150 K and then cooled over a total timescale of 20 kyr. Effects on ice loss and re-accumulation by the changed gas density, the maximum temperature, the irradiation intensity, the size-dependent grain temperature trend, and the distribution of the ice mass among the grain-size bins were investigated.<i>Results<i/>. A massive selective redistribution of ices exclusively onto the surface of the coldest grain-size bin occurs in all models. The redistribution starts already during the heating stage, where ices that are sublimated from warmer grains re-adsorb onto colder grains before complete sublimation. During the cooling stage, the sublimated molecules re-freeze again onto the coldest grains. In the case of full sublimation, this re-adsorption is delayed and occurs at lower temperatures because a bare grain surface has lower molecular desorption energies in our model.<i>Conclusions<i/>. Most protostellar envelope grains enter the PPD ice poor (bare). Ices are carried by a single coldest grain-size bin, here representing 12% of the total grain surface area. This bare ice-grain dualism can affect the rate of the grain coagulation. The ice components are stratified on the grains according to their sublimation temperatures.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427434","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 : 2025-02-14DOI: 10.1051/0004-6361/202450943
M. Ginolin, M. Rigault, Y. Copin, B. Popovic, G. Dimitriadis, A. Goobar, J. Johansson, K. Maguire, J. Nordin, M. Smith, M. Aubert, C. Barjou-Delayre, U. Burgaz, B. Carreres, S. Dhawan, M. Deckers, F. Feinstein, D. Fouchez, L. Galbany, C. Ganot, T. de Jaeger, Y.-L. Kim, D. Kuhn, L. Lacroix, T. E. Müller-Bravo, P. Nugent, B. Racine, P. Rosnet, D. Rosselli, F. Ruppin, J. Sollerman, J. H. Terwel, A. Townsend, R. Dekany, M. Graham, M. Kasliwal, S. L. Groom, J. Purdum, B. Rusholme, S. van der Walt
Context. As type Ia supernova cosmology transitions from a statistics-dominated to a systematics-dominated era, it is crucial to understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming from astrophysical biases. Type Ia supernovae are standardisable candles whose absolute magnitude reaches a scatter of typically 0.15 mag when empirical correlations with their light-curve stretch and colour and with their environmental properties are accounted for.Aims. We investigate the dependence of the standardisation process of type Ia supernovae on the astrophysical environment to ultimately reduce their scatter in magnitude. We focus on colour standardisation.Methods. We used the volume-limited ZTF SN Ia DR2 sample, which offers unprecedented statistics for the low-redshift (z < 0.06) range. We first studied the colour distribution with a focus on the effects of dust to then select a dustless subsample of objects that originated in environments with a low stellar mass and in the outskirts of their host galaxies. We then examined the colour-residual relation and its associated parameter β. Finally, we investigated the colour dependence of the environment-dependent magnitude offsets (steps) to separate their intrinsic and extrinsic components.Results. Our sample of nearly 1000 supernovae probes the red tail of the colour distribution up to c = 0.8. The dustless sample exhibits a significantly shorter red tail (4.3σ) than the whole sample, but the distributions around c ∼ 0 are similar for both samples. This suggests that the reddening above c ≥ 0.2 is dominated by interstellar dust absorption of the host and that the remaining colour scatter has an intrinsic origin. The colour-residual relation is linear with light-curve colour. We found indications of a potential evolution of β with the stellar host mass, with β ∼ 3.6 for low-mass galaxies, compared to β = 3.05 ± 0.06 for the full sample. Finally, in contrast to recent claims from the literature, we found no evolution of steps as a function of light-curve colour. This suggests that dust may not be the dominating mechanism for the dependence on the environment of the magnitude of type Ia supernovae.
{"title":"ZTF SN Ia DR2: Colour standardisation of type Ia supernovae and its dependence on the environment","authors":"M. Ginolin, M. Rigault, Y. Copin, B. Popovic, G. Dimitriadis, A. Goobar, J. Johansson, K. Maguire, J. Nordin, M. Smith, M. Aubert, C. Barjou-Delayre, U. Burgaz, B. Carreres, S. Dhawan, M. Deckers, F. Feinstein, D. Fouchez, L. Galbany, C. Ganot, T. de Jaeger, Y.-L. Kim, D. Kuhn, L. Lacroix, T. E. Müller-Bravo, P. Nugent, B. Racine, P. Rosnet, D. Rosselli, F. Ruppin, J. Sollerman, J. H. Terwel, A. Townsend, R. Dekany, M. Graham, M. Kasliwal, S. L. Groom, J. Purdum, B. Rusholme, S. van der Walt","doi":"10.1051/0004-6361/202450943","DOIUrl":"https://doi.org/10.1051/0004-6361/202450943","url":null,"abstract":"<i>Context.<i/> As type Ia supernova cosmology transitions from a statistics-dominated to a systematics-dominated era, it is crucial to understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming from astrophysical biases. Type Ia supernovae are standardisable candles whose absolute magnitude reaches a scatter of typically 0.15 mag when empirical correlations with their light-curve stretch and colour and with their environmental properties are accounted for.<i>Aims.<i/> We investigate the dependence of the standardisation process of type Ia supernovae on the astrophysical environment to ultimately reduce their scatter in magnitude. We focus on colour standardisation.<i>Methods.<i/> We used the volume-limited ZTF SN Ia DR2 sample, which offers unprecedented statistics for the low-redshift (<i>z<i/> < 0.06) range. We first studied the colour distribution with a focus on the effects of dust to then select a dustless subsample of objects that originated in environments with a low stellar mass and in the outskirts of their host galaxies. We then examined the colour-residual relation and its associated parameter <i>β<i/>. Finally, we investigated the colour dependence of the environment-dependent magnitude offsets (steps) to separate their intrinsic and extrinsic components.<i>Results.<i/> Our sample of nearly 1000 supernovae probes the red tail of the colour distribution up to <i>c<i/> = 0.8. The dustless sample exhibits a significantly shorter red tail (4.3<i>σ<i/>) than the whole sample, but the distributions around <i>c<i/> ∼ 0 are similar for both samples. This suggests that the reddening above <i>c<i/> ≥ 0.2 is dominated by interstellar dust absorption of the host and that the remaining colour scatter has an intrinsic origin. The colour-residual relation is linear with light-curve colour. We found indications of a potential evolution of <i>β<i/> with the stellar host mass, with <i>β<i/> ∼ 3.6 for low-mass galaxies, compared to <i>β<i/> = 3.05 ± 0.06 for the full sample. Finally, in contrast to recent claims from the literature, we found no evolution of steps as a function of light-curve colour. This suggests that dust may not be the dominating mechanism for the dependence on the environment of the magnitude of type Ia supernovae.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"68 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427412","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 : 2025-02-14DOI: 10.1051/0004-6361/202450951
M. Aubert, P. Rosnet, B. Popovic, F. Ruppin, M. Smith, M. Rigault, G. Dimitriadis, A. Goobar, J. Johansson, C. Barjou-Delayre, U. Burgaz, B. Carreres, F. Feinstein, D. Fouchez, L. Galbany, M. Ginolin, T. de Jaeger, M. M. Kasliwal, Y.-L. Kim, L. Lacroix, F. J. Masci, T. E. Müller-Bravo, B. Racine, C. Ravoux, N. Regnault, R. L. Riddle, D. Rosselli, B. Rusholme, R. Smith, J. Sollerman, J. H. Terwel, A. Townsend
Context. The unprecedented statistics of detected Type Ia supernovae (SNe Ia) brought by the Zwicky Transient Facility (ZTF) enable us to probe the impact of the large-scale structure (LSS) on the properties of these objects.Aims. The goal of this paper is to explore the possible impact of the under-dense part of the LSS on the intrinsic SALT2 light-curve properties of SNe Ia and uncover possible biases in SN Ia analyses.Methods. With a volume-limited selection of ZTF-Cosmo-DR2 SNe Ia overlapping with the SDSS-DR7 survey footprint, we investigated the distribution of their properties with regard to voids detected in the SDSS-DR7 galaxy sample. We further used Voronoi volumes as a proxy for local density environments within the LSS.Results. We find a moderate dependency of the stretch on the localisation around the void centre and none when considering colour. The local Voronoi volumes mostly affect the fraction of low- and high-stretch supernovae.Conclusions. With the presently available statistics, we consider that the impact of high- or low-local-density environment can be considered as a proxy for the colour of the host galaxy. Under-dense environments should not cause any biases in analyses of supernova.
{"title":"ZTF SN Ia DR2: Exploring SN Ia properties in the vicinity of under-dense environments","authors":"M. Aubert, P. Rosnet, B. Popovic, F. Ruppin, M. Smith, M. Rigault, G. Dimitriadis, A. Goobar, J. Johansson, C. Barjou-Delayre, U. Burgaz, B. Carreres, F. Feinstein, D. Fouchez, L. Galbany, M. Ginolin, T. de Jaeger, M. M. Kasliwal, Y.-L. Kim, L. Lacroix, F. J. Masci, T. E. Müller-Bravo, B. Racine, C. Ravoux, N. Regnault, R. L. Riddle, D. Rosselli, B. Rusholme, R. Smith, J. Sollerman, J. H. Terwel, A. Townsend","doi":"10.1051/0004-6361/202450951","DOIUrl":"https://doi.org/10.1051/0004-6361/202450951","url":null,"abstract":"<i>Context.<i/> The unprecedented statistics of detected Type Ia supernovae (SNe Ia) brought by the Zwicky Transient Facility (ZTF) enable us to probe the impact of the large-scale structure (LSS) on the properties of these objects.<i>Aims.<i/> The goal of this paper is to explore the possible impact of the under-dense part of the LSS on the intrinsic SALT2 light-curve properties of SNe Ia and uncover possible biases in SN Ia analyses.<i>Methods.<i/> With a volume-limited selection of ZTF-Cosmo-DR2 SNe Ia overlapping with the SDSS-DR7 survey footprint, we investigated the distribution of their properties with regard to voids detected in the SDSS-DR7 galaxy sample. We further used Voronoi volumes as a proxy for local density environments within the LSS.<i>Results.<i/> We find a moderate dependency of the stretch on the localisation around the void centre and none when considering colour. The local Voronoi volumes mostly affect the fraction of low- and high-stretch supernovae.<i>Conclusions.<i/> With the presently available statistics, we consider that the impact of high- or low-local-density environment can be considered as a proxy for the colour of the host galaxy. Under-dense environments should not cause any biases in analyses of supernova.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427411","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 : 2025-02-14DOI: 10.1051/0004-6361/202453009
J. Jormanainen, T. Hovatta, E. Lindfors, A. Berdyugin, W. Chamani, V. Fallah Ramazani, H. Jermak, S. G. Jorstad, A. Lähteenmäki, C. McCall, K. Nilsson, P. Smith, I. A. Steele, J. Tammi, M. Tornikoski, F. Wierda
OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and 2017 (MJD 57300–58000) contains several interesting events that we re-contextualise in this study. We collected optical photometric and polarimetric data from several telescopes and obtained high-cadence light curves from this period. In the radio band, we collected millimetre-wavelength polarisation data from the AMAPOLA programme. We combined them with existing multi-frequency polarimetric radio results and the results of very long-baseline interferometry imaging with the Global mm-VLBI Array at 86 GHz. In December 2015, an optical flare was seen according to the general relativistic binary black hole model. We suggest that the overall activity near the accretion disk and the jet base during this time may be connected to the onset of a new moving component, K, seen in the jet in March 2017. With the additional optical data, we find a fast polarisation angle rotation of ∼210° coinciding with the December 2015 flare, hinting at a possible link between these events. Based on the 86 GHz images, we calculated a new speed of 0.12 mas/yr for K, which places it inside the core at the time of the 2015 flare. This speed also supports the scenario in which the passage of K through the quasi-stationary feature S1 could have been the trigger for the very high-energy gamma-ray flare of OJ 287 seen in February 2017. With the millimetre-polarisation data, we establish that these bands follow the centimetre-band data but show a difference during the time when K passes through S1. This indicates that the millimetre bands trace substructures of the jet that are still unresolved in the centimetre bands.
{"title":"The polarisation behaviour of OJ 287 viewed through radio, millimetre, and optical observations between 2015 and 2017","authors":"J. Jormanainen, T. Hovatta, E. Lindfors, A. Berdyugin, W. Chamani, V. Fallah Ramazani, H. Jermak, S. G. Jorstad, A. Lähteenmäki, C. McCall, K. Nilsson, P. Smith, I. A. Steele, J. Tammi, M. Tornikoski, F. Wierda","doi":"10.1051/0004-6361/202453009","DOIUrl":"https://doi.org/10.1051/0004-6361/202453009","url":null,"abstract":"OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and 2017 (MJD 57300–58000) contains several interesting events that we re-contextualise in this study. We collected optical photometric and polarimetric data from several telescopes and obtained high-cadence light curves from this period. In the radio band, we collected millimetre-wavelength polarisation data from the AMAPOLA programme. We combined them with existing multi-frequency polarimetric radio results and the results of very long-baseline interferometry imaging with the Global mm-VLBI Array at 86 GHz. In December 2015, an optical flare was seen according to the general relativistic binary black hole model. We suggest that the overall activity near the accretion disk and the jet base during this time may be connected to the onset of a new moving component, K, seen in the jet in March 2017. With the additional optical data, we find a fast polarisation angle rotation of ∼210° coinciding with the December 2015 flare, hinting at a possible link between these events. Based on the 86 GHz images, we calculated a new speed of 0.12 mas/yr for K, which places it inside the core at the time of the 2015 flare. This speed also supports the scenario in which the passage of K through the quasi-stationary feature S1 could have been the trigger for the very high-energy gamma-ray flare of OJ 287 seen in February 2017. With the millimetre-polarisation data, we establish that these bands follow the centimetre-band data but show a difference during the time when K passes through S1. This indicates that the millimetre bands trace substructures of the jet that are still unresolved in the centimetre bands.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"30 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427460","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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