Pub Date : 2025-12-12DOI: 10.1051/0004-6361/202554643
D. L. Neuhäuser, R. Neuhäuser, V. Hambaryan, J. Chapman, M. Della Valle
Context. Connections between novae with shells and historical observations are crucial for astrophysical understanding of long-term evolution of shells and cataclysmic variables.Aims. Three of five previously considered links are revisited here: extended features in M22 in BC48, Te-11 in 483, and AT Cnc in 1645. We aim to develop a procedure to check whether these links are credible.Methods. Literal translations of the Chinese texts, historically based arguments, and close readings are combined with astrophysics, (peak brightness, decay time estimate, shell age expansion model calculation, etc.).Results. (a) Nandou’s second star, near which the BC48 ‘guest star’ was reported, is identified as τ Sgr, not λ Sgr, far from the M22 location. A nova in M22 would peak at only m = 6.4 ± 1.4 mag, and thus a description as a ‘blue-white’ ‘melon’ does not fit; it was likely a comet. (b) The imprecise position (‘Shen[’s] east’) of the ‘guest star’ in 483, its extended (dipper-like) radiance, and the context speak for a bolide. Considering the new (larger) Gaia distance and small extinction towards Te-11 (outside a cloud), its bi-polar morphology and current expansion velocity point to a planetary nebula; as a nova, the shell expansion age is ∼1100–2000 yr from detailed supersonic expansion calculations. (c) Most certainly, Mars was meant when the source for 1645 reported ‘a large star entered Yugui’; the verb implies motion. AT Cnc lies neither in Yugui’s asterism box nor in the eponymous lunar mansion range. The fluid drag expansion age of AT Cancri’s ejecta is ∼128–631 yr.Conclusions. All three exact ages are unsubstantiated. True novae or nova shells can be connected to historical records only if the position and object type are plausible. Duration, brightness (light curve), and color (evolution) should fit and could provide more astrophysical insight. Then, shell ages are sufficiently precise for properly studying secular evolution of novae, shell sizes, Hα luminosities, long-term decay, etc.
{"title":"Challenging historical novae: AT Cnc (1645), Te-11 (483), and M22 (BC 48) revisited","authors":"D. L. Neuhäuser, R. Neuhäuser, V. Hambaryan, J. Chapman, M. Della Valle","doi":"10.1051/0004-6361/202554643","DOIUrl":"https://doi.org/10.1051/0004-6361/202554643","url":null,"abstract":"<i>Context.<i/> Connections between novae with shells and historical observations are crucial for astrophysical understanding of long-term evolution of shells and cataclysmic variables.<i>Aims.<i/> Three of five previously considered links are revisited here: extended features in M22 in BC48, Te-11 in 483, and AT Cnc in 1645. We aim to develop a procedure to check whether these links are credible.<i>Methods.<i/> Literal translations of the Chinese texts, historically based arguments, and close readings are combined with astrophysics, (peak brightness, decay time estimate, shell age expansion model calculation, etc.).<i>Results.<i/> (a) Nandou’s second star, near which the BC48 ‘guest star’ was reported, is identified as <i>τ<i/> Sgr, not <i>λ<i/> Sgr, far from the M22 location. A nova in M22 would peak at only <i>m<i/> = 6.4 ± 1.4 mag, and thus a description as a ‘blue-white’ ‘melon’ does not fit; it was likely a comet. (b) The imprecise position (‘Shen[’s] east’) of the ‘guest star’ in 483, its extended (dipper-like) radiance, and the context speak for a bolide. Considering the new (larger) Gaia distance and small extinction towards Te-11 (outside a cloud), its bi-polar morphology and current expansion velocity point to a planetary nebula; as a nova, the shell expansion age is ∼1100–2000 yr from detailed supersonic expansion calculations. (c) Most certainly, Mars was meant when the source for 1645 reported ‘a large star entered Yugui’; the verb implies motion. AT Cnc lies neither in Yugui’s asterism box nor in the eponymous lunar mansion range. The fluid drag expansion age of AT Cancri’s ejecta is ∼128–631 yr.<i>Conclusions.<i/> All three exact ages are unsubstantiated. True novae or nova shells can be connected to historical records only if the position and object type are plausible. Duration, brightness (light curve), and color (evolution) should fit and could provide more astrophysical insight. Then, shell ages are sufficiently precise for properly studying secular evolution of novae, shell sizes, H<i>α<i/> luminosities, long-term decay, etc.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753248","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 : 2025-12-12DOI: 10.1051/0004-6361/202557359
J. M. Almenara, A. Leleu, T. Guillot, R. Mardling, F. Bouchy, T. Forveille, J. Winn, L. Abe, M. Beltrame, P. Bendjoya, X. Bonfils, A. Deline, J.-B. Delisle, R. F. Díaz, E. Fridén, M. Hobson, R. M. Hoogenboom, J. M. Jenkins, J. Korth, M. Lendl, D. Mékarnia, A. C. Petit, M. Rosenqvist, O. Suárez, A. H. M. J. Triaud, S. Udry
We report the confirmation and initial characterization of a compact and dynamically rich multiple giant planet system orbiting the solar analog TOI-7510. The system was recently identified as a candidate two-planet system in a machine-learning search of the TESS light curves. Using TESS data and photometric follow-up observations with ASTEP, CHEOPS, and EulerCam, we show that one transit was initially misattributed and that the system consists of three transiting giant planets with orbital periods of 11.5, 22.6, and 48.9 days. The planets have radii of 0.65, 0.96, and 0.94 RJ, making them the largest known trio of transiting planets. The system architecture lies near a 4:2:1 mean motion resonant chain, inducing large transit timing variations for all three planets. Photodynamical modeling gives mass estimates of 0.057, 0.41, and 0.60 MJ and favors low eccentricities and mutual inclinations. TOI-7510 is an interesting system for investigating the dynamical interactions and formation histories of compact systems of giant planets.
{"title":"TOI-7510: A solar-analog system of three transiting giant planets near a Laplace resonance chain★","authors":"J. M. Almenara, A. Leleu, T. Guillot, R. Mardling, F. Bouchy, T. Forveille, J. Winn, L. Abe, M. Beltrame, P. Bendjoya, X. Bonfils, A. Deline, J.-B. Delisle, R. F. Díaz, E. Fridén, M. Hobson, R. M. Hoogenboom, J. M. Jenkins, J. Korth, M. Lendl, D. Mékarnia, A. C. Petit, M. Rosenqvist, O. Suárez, A. H. M. J. Triaud, S. Udry","doi":"10.1051/0004-6361/202557359","DOIUrl":"https://doi.org/10.1051/0004-6361/202557359","url":null,"abstract":"We report the confirmation and initial characterization of a compact and dynamically rich multiple giant planet system orbiting the solar analog TOI-7510. The system was recently identified as a candidate two-planet system in a machine-learning search of the TESS light curves. Using TESS data and photometric follow-up observations with ASTEP, CHEOPS, and EulerCam, we show that one transit was initially misattributed and that the system consists of three transiting giant planets with orbital periods of 11.5, 22.6, and 48.9 days. The planets have radii of 0.65, 0.96, and 0.94 R<sub>J<sub/>, making them the largest known trio of transiting planets. The system architecture lies near a 4:2:1 mean motion resonant chain, inducing large transit timing variations for all three planets. Photodynamical modeling gives mass estimates of 0.057, 0.41, and 0.60 M<sub>J<sub/> and favors low eccentricities and mutual inclinations. TOI-7510 is an interesting system for investigating the dynamical interactions and formation histories of compact systems of giant planets.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753262","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 : 2025-12-12DOI: 10.1051/0004-6361/202557567
L. Briganti, W. E. van Rossem, A. Miglio, A. Bragaglia, M. Matteuzzi
Blue straggler stars (BSSs) are exotic objects, which, being the results of processes such as mass transfer, mergers, or collisions, are considered key objects in the study of their host clusters’ dynamics. While many studies on astrometric, spectroscopic, and photometric properties of BSSs in clusters have been conducted, there are few works in the literature regarding their pulsations and internal structure, which can indeed retain traces of their origin. In this work we computed and analysed a grid of collisional BSSs at low metallicity (Z = 0.01 Z⊙), finding that collision products present a peculiar chemical stratification that leads to periodicities in the period-spacing pattern of high-order gravity modes. These seismic fingerprints provide a unique opportunity to constrain the formation pathways of BSSs in globular clusters.
{"title":"Predictions of gravity mode pulsations of collisional blue straggler stars in globular clusters","authors":"L. Briganti, W. E. van Rossem, A. Miglio, A. Bragaglia, M. Matteuzzi","doi":"10.1051/0004-6361/202557567","DOIUrl":"https://doi.org/10.1051/0004-6361/202557567","url":null,"abstract":"Blue straggler stars (BSSs) are exotic objects, which, being the results of processes such as mass transfer, mergers, or collisions, are considered key objects in the study of their host clusters’ dynamics. While many studies on astrometric, spectroscopic, and photometric properties of BSSs in clusters have been conducted, there are few works in the literature regarding their pulsations and internal structure, which can indeed retain traces of their origin. In this work we computed and analysed a grid of collisional BSSs at low metallicity (<i>Z<i/> = 0.01 <i>Z<i/><sub>⊙<sub/>), finding that collision products present a peculiar chemical stratification that leads to periodicities in the period-spacing pattern of high-order gravity modes. These seismic fingerprints provide a unique opportunity to constrain the formation pathways of BSSs in globular clusters.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"68 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753244","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 : 2025-12-12DOI: 10.1051/0004-6361/202556041
M. van Noort, J. Hölken, H.-P. Doerr, J. Chae, W. Cao, N. Gorceix, J. Kang, K. Ahn, S. K. Solanki
Context. Small-scale events measuring only tens of kilometres can have significant implications for the overall energy state of various layers of the solar atmosphere. Current spectro-polarimetric observations lack either spatial or spectral resolution for a comprehensive study of these small-scale events.Aims. The slit-scanning spectro-polarimetric instrument described here is designed for spectral image reconstruction and, in combination with the excellent optical performance of the 1.6 metre Goode Solar Telescope, yields spectral hypercubes of the highest spatial and spectral resolution. Additionally, the instrument offers a huge spectral window of more than 30 Å, allowing many solar absorption lines to be observed simultaneously.Methods. We extended the existing Fast Imaging Solar Spectrograph (FISS) instrument with polarimetric capabilities, new customized cameras, and a context imager. We applied numerical methods to measure and correct for field-dependent instrumental and atmospheric degradations, to obtain diffraction-limited spectro-polarimetric scans.Results. In this work we present the instrument design, the data reduction workflow, and the first-light results. Compared to a typical HINODE/SP dataset, we find a higher signal-to-noise ratio in our data within the resolution limits of the respective telescopes when utilizing the signal of all simultaneously observed spectral lines.Conclusions. We have obtained the first diffraction-limited full Stokes spectro-polarimetric datasets recorded with a slit-scanning spectrograph on a telescope with an aperture exceeding 1.5 metres.
{"title":"Large-aperture diffraction-limited spectro-polarimetry with FISS-SP","authors":"M. van Noort, J. Hölken, H.-P. Doerr, J. Chae, W. Cao, N. Gorceix, J. Kang, K. Ahn, S. K. Solanki","doi":"10.1051/0004-6361/202556041","DOIUrl":"https://doi.org/10.1051/0004-6361/202556041","url":null,"abstract":"<i>Context.<i/> Small-scale events measuring only tens of kilometres can have significant implications for the overall energy state of various layers of the solar atmosphere. Current spectro-polarimetric observations lack either spatial or spectral resolution for a comprehensive study of these small-scale events.<i>Aims.<i/> The slit-scanning spectro-polarimetric instrument described here is designed for spectral image reconstruction and, in combination with the excellent optical performance of the 1.6 metre Goode Solar Telescope, yields spectral hypercubes of the highest spatial and spectral resolution. Additionally, the instrument offers a huge spectral window of more than 30 Å, allowing many solar absorption lines to be observed simultaneously.<i>Methods.<i/> We extended the existing Fast Imaging Solar Spectrograph (FISS) instrument with polarimetric capabilities, new customized cameras, and a context imager. We applied numerical methods to measure and correct for field-dependent instrumental and atmospheric degradations, to obtain diffraction-limited spectro-polarimetric scans.<i>Results.<i/> In this work we present the instrument design, the data reduction workflow, and the first-light results. Compared to a typical HINODE/SP dataset, we find a higher signal-to-noise ratio in our data within the resolution limits of the respective telescopes when utilizing the signal of all simultaneously observed spectral lines.<i>Conclusions.<i/> We have obtained the first diffraction-limited full Stokes spectro-polarimetric datasets recorded with a slit-scanning spectrograph on a telescope with an aperture exceeding 1.5 metres.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753249","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 : 2025-12-12DOI: 10.1051/0004-6361/202556850
Jelle Vandersnickt, Vincent Vanlaer, Mathijs Vanrespaille, Conny Aerts
Context. Internal magnetic fields are an elusive component of stellar structure. However, they can play an important role in stellar structure and evolution models through efficient angular momentum transport and through their impact on internal mixing.Aims. We strive to explain the nine components of one frequency multiplet identified as a low-order quadrupole gravity mode detected in the light curve of the β Cep pulsator HD 192575 assembled by the Transiting Exoplanet Survey Satellite (TESS).Methods. We updated the frequencies of the quadrupole mode under investigation using a standard pre-whitening method applied to the 1951.46 d TESS light curve. This showed that an internal magnetic field is required to simultaneously explain all nine components. We implemented theoretical pulsation computations applicable to the low-order modes of a β Cep pulsator including the Coriolis force as well as a magnetic field that is misaligned with respect to the rotation axis. We applied the theoretical description to perform asteroseismic modelling of the amplitudes and frequencies in the multiplet of the quadrupole g-mode of this evolved β Cep star.Results. Pulsation predictions based on the measured internal rotation frequency of the star cannot explain the observed nine-component frequency splittings of the quadrupole low-order gravity mode. By contrast, we show that the combined effect of the Coriolis force caused by the near-core rotation with a period of ∼5.3 d and the Lorentz force due to an internal inclined magnetic field with a maximum strength of ∼24 kG does provide a proper explanation of the nine multiplet frequencies and their relative amplitudes.Conclusions. Given HD 192575’s stellar mass of about 12 M⊙, this work presents the detection and magneto-gravito-asteroseismic modelling of a stable internal magnetic field buried inside an evolved rotating supernova progenitor.
{"title":"Asteroseismic detection of an internal magnetic field in the B0.5V pulsator HD 192575","authors":"Jelle Vandersnickt, Vincent Vanlaer, Mathijs Vanrespaille, Conny Aerts","doi":"10.1051/0004-6361/202556850","DOIUrl":"https://doi.org/10.1051/0004-6361/202556850","url":null,"abstract":"<i>Context.<i/> Internal magnetic fields are an elusive component of stellar structure. However, they can play an important role in stellar structure and evolution models through efficient angular momentum transport and through their impact on internal mixing.<i>Aims.<i/> We strive to explain the nine components of one frequency multiplet identified as a low-order quadrupole gravity mode detected in the light curve of the <i>β<i/> Cep pulsator HD 192575 assembled by the Transiting Exoplanet Survey Satellite (TESS).<i>Methods.<i/> We updated the frequencies of the quadrupole mode under investigation using a standard pre-whitening method applied to the 1951.46 d TESS light curve. This showed that an internal magnetic field is required to simultaneously explain all nine components. We implemented theoretical pulsation computations applicable to the low-order modes of a <i>β<i/> Cep pulsator including the Coriolis force as well as a magnetic field that is misaligned with respect to the rotation axis. We applied the theoretical description to perform asteroseismic modelling of the amplitudes and frequencies in the multiplet of the quadrupole g-mode of this evolved <i>β<i/> Cep star.<i>Results.<i/> Pulsation predictions based on the measured internal rotation frequency of the star cannot explain the observed nine-component frequency splittings of the quadrupole low-order gravity mode. By contrast, we show that the combined effect of the Coriolis force caused by the near-core rotation with a period of ∼5.3 d and the Lorentz force due to an internal inclined magnetic field with a maximum strength of ∼24 kG does provide a proper explanation of the nine multiplet frequencies and their relative amplitudes.<i>Conclusions.<i/> Given HD 192575’s stellar mass of about 12 M<sub>⊙<sub/>, this work presents the detection and magneto-gravito-asteroseismic modelling of a stable internal magnetic field buried inside an evolved rotating supernova progenitor.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"162 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753246","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 : 2025-12-12DOI: 10.1051/0004-6361/202557622
Daniel Íñiguez-Pascual, Daniele Viganò, Diego F. Torres
Context. The observational efficiency of pulsars, defined as the ratio of the observationally derived isotropic-equivalent luminosity, 4πdobs2Fobs, where Fobs is the average pulsed energy flux of a pulsar and dobs is its estimated distance, to its energy budget, shows a wide range of values. This dispersion is believed to be a combination of beaming effects, different geometries, and case-by-case variability of the emission mechanism efficiency, but it is not clear in what proportion.Aims. In this work we focused on the γ-ray range and analysed the four main ingredients that likely contribute to this dispersion: the geometrical term arising from the anisotropic emission (beaming), viewing and inclination angles, the uncertainty on the pulsar distance, the uncertainty on the moment of inertia, and the intrinsic efficiency of the mechanism producing the γ-ray emission.Methods. Estimating the expected ranges of the moment of inertia and the distance errors, and considering a geometrical and spectral model that we have recently used to fit the light curves and spectra of the entire γ-ray pulsar population, we estimate the a priori distribution of the first three ingredients in order to obtain the a posteriori distribution of the intrinsic efficiency of the mechanism.Results. We found the latter to peak at ∼5 − 15% (depending on the trial distribution) and to have a dispersion of around one order of magnitude. That is, we found the intrinsic efficiency of the mechanism to be the leading factor in the observed dispersion. In addition, we found little sensitivity of these results on different distributions of the estimated pulsar distance errors, and saw that the weak, alleged correlation with the spin-down power can only explain part of the observed dispersion. This methodology can be easily applied to other geometrical models of the emission, to test the sensitivity of these results on the beaming distribution.
{"title":"The dispersion in pulsar γ-ray efficiency","authors":"Daniel Íñiguez-Pascual, Daniele Viganò, Diego F. Torres","doi":"10.1051/0004-6361/202557622","DOIUrl":"https://doi.org/10.1051/0004-6361/202557622","url":null,"abstract":"<i>Context.<i/> The observational efficiency of pulsars, defined as the ratio of the observationally derived isotropic-equivalent luminosity, 4<i>πd<i/><sub>obs<sub/><sup>2<sup/><i>F<i/><sub>obs<sub/>, where <i>F<i/><sub>obs<sub/> is the average pulsed energy flux of a pulsar and <i>d<i/><sub>obs<sub/> is its estimated distance, to its energy budget, shows a wide range of values. This dispersion is believed to be a combination of beaming effects, different geometries, and case-by-case variability of the emission mechanism efficiency, but it is not clear in what proportion.<i>Aims.<i/> In this work we focused on the <i>γ<i/>-ray range and analysed the four main ingredients that likely contribute to this dispersion: the geometrical term arising from the anisotropic emission (beaming), viewing and inclination angles, the uncertainty on the pulsar distance, the uncertainty on the moment of inertia, and the intrinsic efficiency of the mechanism producing the <i>γ<i/>-ray emission.<i>Methods.<i/> Estimating the expected ranges of the moment of inertia and the distance errors, and considering a geometrical and spectral model that we have recently used to fit the light curves and spectra of the entire <i>γ<i/>-ray pulsar population, we estimate the a priori distribution of the first three ingredients in order to obtain the a posteriori distribution of the intrinsic efficiency of the mechanism.<i>Results.<i/> We found the latter to peak at ∼5 − 15% (depending on the trial distribution) and to have a dispersion of around one order of magnitude. That is, we found the intrinsic efficiency of the mechanism to be the leading factor in the observed dispersion. In addition, we found little sensitivity of these results on different distributions of the estimated pulsar distance errors, and saw that the weak, alleged correlation with the spin-down power can only explain part of the observed dispersion. This methodology can be easily applied to other geometrical models of the emission, to test the sensitivity of these results on the beaming distribution.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"20 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753258","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 : 2025-12-11DOI: 10.1051/0004-6361/202556790
F. Namouni
Context. Numerical simulations of the 4.5 Gyr past evolution of high-inclination Centaurs show that they originated from orbits beyond Neptune that were perpendicular to the Solar System’s invariable plane in a region called the polar corridor. The existence of the polar corridor is explained by the Tisserand inclination pathways followed by Neptune-crossing objects in the three-body problem. Recently, a study of Centaur injection in the three-body problem has shown that Neptune-crossing trans-Neptunian objects (TNOs) in the polar corridor with semimajor axes in the range [40:160] au have dynamical times that exceed the Solar System’s age, suggesting the possible presence of long-lived reservoirs that produce high-inclination Centaurs.Aims. We aim to numerically demonstrate the existence of such reservoirs in the Solar System by simulating the TNOs’ time-forward evolution under the gravitational perturbations of the giant planets, the Galactic tide, and passing stars. We also aim to assess the efficiency of Centaur injection as a function of the initial inclination and determine if high-inclination Centaurs can be produced by low-inclination reservoirs.Methods. The motion of the giant planets, TNOs, and passing stars was simulated using the IAS15 N-body numerical integrator of the REBOUND package. The Galactic tide was included using the REBOUNDx package. Two TNO orbit types were considered in the semimajor axis range [40:140] au: cold TNOs with circular orbits and hot TNOs with a perihelion range of [32:50] au. The TNO Tisserand parameters, T, with respect to Neptune were taken in the range [−2:2.8] which corresponds to inclinations far from Neptune in the range [8°:135°], in order to examine Centaur injection at low and high initial inclinations.Results. We find that TNO reservoirs in the semimajor axis range [50:140] au are long-lived and their populations peak at T = 0.5 and T = −1.5. Saturn is found to induce secondary structures in the polar corridor by holding the perihelia of a fraction of high-inclination reservoir material. We find that the Centaur inclination at minimum semimajor axis depends linearly on the Tisserand parameter regardless of the initial semimajor axis. Its amplitude shows that low-inclination reservoirs such as the early protoplanetary disk are unlikely to produce high-inclination Centaurs, in contrast to reservoirs in the polar corridor.Conclusions. We have identified the likely location of the closest reservoirs to Neptune populated by TNOs captured in the early Solar System that produce high-inclination Centaurs. The Legacy Survey of Space and Time of the Vera Rubin Observatory will be able to constrain the reservoirs’ extent and population size.
{"title":"High-inclination Centaur reservoirs beyond Neptune","authors":"F. Namouni","doi":"10.1051/0004-6361/202556790","DOIUrl":"https://doi.org/10.1051/0004-6361/202556790","url":null,"abstract":"<i>Context.<i/> Numerical simulations of the 4.5 Gyr past evolution of high-inclination Centaurs show that they originated from orbits beyond Neptune that were perpendicular to the Solar System’s invariable plane in a region called the polar corridor. The existence of the polar corridor is explained by the Tisserand inclination pathways followed by Neptune-crossing objects in the three-body problem. Recently, a study of Centaur injection in the three-body problem has shown that Neptune-crossing trans-Neptunian objects (TNOs) in the polar corridor with semimajor axes in the range [40:160] au have dynamical times that exceed the Solar System’s age, suggesting the possible presence of long-lived reservoirs that produce high-inclination Centaurs.<i>Aims.<i/> We aim to numerically demonstrate the existence of such reservoirs in the Solar System by simulating the TNOs’ time-forward evolution under the gravitational perturbations of the giant planets, the Galactic tide, and passing stars. We also aim to assess the efficiency of Centaur injection as a function of the initial inclination and determine if high-inclination Centaurs can be produced by low-inclination reservoirs.<i>Methods.<i/> The motion of the giant planets, TNOs, and passing stars was simulated using the IAS15 <i>N<i/>-body numerical integrator of the REBOUND package. The Galactic tide was included using the REBOUNDx package. Two TNO orbit types were considered in the semimajor axis range [40:140] au: cold TNOs with circular orbits and hot TNOs with a perihelion range of [32:50] au. The TNO Tisserand parameters, <i>T<i/>, with respect to Neptune were taken in the range [−2:2.8] which corresponds to inclinations far from Neptune in the range [8<sup>°<sup/>:135<sup>°<sup/>], in order to examine Centaur injection at low and high initial inclinations.<i>Results.<i/> We find that TNO reservoirs in the semimajor axis range [50:140] au are long-lived and their populations peak at <i>T<i/> = 0.5 and <i>T<i/> = −1.5. Saturn is found to induce secondary structures in the polar corridor by holding the perihelia of a fraction of high-inclination reservoir material. We find that the Centaur inclination at minimum semimajor axis depends linearly on the Tisserand parameter regardless of the initial semimajor axis. Its amplitude shows that low-inclination reservoirs such as the early protoplanetary disk are unlikely to produce high-inclination Centaurs, in contrast to reservoirs in the polar corridor.<i>Conclusions.<i/> We have identified the likely location of the closest reservoirs to Neptune populated by TNOs captured in the early Solar System that produce high-inclination Centaurs. The Legacy Survey of Space and Time of the <i>Vera Rubin<i/> Observatory will be able to constrain the reservoirs’ extent and population size.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145718449","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 : 2025-12-10DOI: 10.1051/0004-6361/202555680
Charlotte Gehan
It has been observed that the fraction of low-mass (LM) stars (M ≤ 1.5 M⊙) showing photospheric activity in their light curve is larger on the horizontal branch (HB) than during the prior, red giant branch (RGB) phase, while the opposite trend has been observed for intermediate-mass (IM) stars (M > 1.5 M⊙). One hypothesis is that LM red giants (RGs) engulf more planets than IM RGs, which results in a faster surface rotation and a higher magnetic activity. This hypothesis is based on the fact that LM stars reach a maximum radius at the RGB tip that is much larger than that achieved for IM stars, making them more likely to engulf planets. However, we need to study the evolution of the active star fraction along the RGB to firmly check this hypothesis. I used independent indicators tracing the activity level in the chromosphere based on the Ca II H&K, Hα, Mg I, and infrared Ca II spectral lines from LAMOST data for ∼3000 RGs whose evolutionary stage has been determined by asteroseismology with the Kepler mission. I found that the fraction of active stars shows different trends for LM and IM stars along the RGB, decreasing for IM stars, but unexpectedly increasing for LM stars. Such an increase cannot be explained by models of single-star evolution and it is consistent with the fact that LM stars are more likely than IM stars to engulf planets. Indeed, the data show that IM main sequence stars exhibit a dearth of planets, which is consistent with predictions from planet formation theory. In addition, I observe that the fraction of active stars tends to increase for both LM and IM stars on the HB, which stands in partial contrast with previous findings. Finally, I discovered that the IM RGB star KIC 9780154 might have engulfed one or more planet(s) as its surface rotation from photometry is twice faster than its envelope rotation from asteroseismology. Characterizing planet engulfment by RGs provides insights into the evolution and fate of most planetary systems, since ∼97% of stars pass through the RG evolution stage.
{"title":"Evolution of stellar magnetic activity: Probing planet engulfment by red giants","authors":"Charlotte Gehan","doi":"10.1051/0004-6361/202555680","DOIUrl":"https://doi.org/10.1051/0004-6361/202555680","url":null,"abstract":"It has been observed that the fraction of low-mass (LM) stars (<i>M<i/> ≤ 1.5 <i>M<i/><sub>⊙<sub/>) showing photospheric activity in their light curve is larger on the horizontal branch (HB) than during the prior, red giant branch (RGB) phase, while the opposite trend has been observed for intermediate-mass (IM) stars (<i>M<i/> > 1.5 <i>M<i/><sub>⊙<sub/>). One hypothesis is that LM red giants (RGs) engulf more planets than IM RGs, which results in a faster surface rotation and a higher magnetic activity. This hypothesis is based on the fact that LM stars reach a maximum radius at the RGB tip that is much larger than that achieved for IM stars, making them more likely to engulf planets. However, we need to study the evolution of the active star fraction along the RGB to firmly check this hypothesis. I used independent indicators tracing the activity level in the chromosphere based on the Ca II H&K, H<i>α<i/>, Mg I, and infrared Ca II spectral lines from LAMOST data for ∼3000 RGs whose evolutionary stage has been determined by asteroseismology with the <i>Kepler<i/> mission. I found that the fraction of active stars shows different trends for LM and IM stars along the RGB, decreasing for IM stars, but unexpectedly increasing for LM stars. Such an increase cannot be explained by models of single-star evolution and it is consistent with the fact that LM stars are more likely than IM stars to engulf planets. Indeed, the data show that IM main sequence stars exhibit a dearth of planets, which is consistent with predictions from planet formation theory. In addition, I observe that the fraction of active stars tends to increase for both LM and IM stars on the HB, which stands in partial contrast with previous findings. Finally, I discovered that the IM RGB star KIC 9780154 might have engulfed one or more planet(s) as its surface rotation from photometry is twice faster than its envelope rotation from asteroseismology. Characterizing planet engulfment by RGs provides insights into the evolution and fate of most planetary systems, since ∼97% of stars pass through the RG evolution stage.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"72 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711527","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 : 2025-12-10DOI: 10.1051/0004-6361/202557141
Daniele Manzoni, Andrea Ferrara
Order-unity star formation efficiencies (SFE) in early galaxies may explain the overabundance of bright galaxies observed by JWST at high redshift. Here we show that Lyman-α (Lyα) radiation pressure limits the gas mass converted into stars, particularly in primordial environments. We have developed a shell model including Lyα feedback, and we validate it with one-dimensional hydrodynamical simulations. To account for Lyα resonant scattering, we adopted the most recent force multiplier fits, including the effect of Lyα photon destruction by dust grains. We find that independent of their gas surface density, Σg, clouds are disrupted on a timescale shorter than the free-fall time and even before supernova explosions if . At log(Z/Z⊙) = − 2, which is relevant for high-redshift galaxies, the SFE is for . The SFE is even lower for decreasing metallicity. Bursts of star formation with near-unity SFEs are possible only for extreme surface densities, , and near-solar metallicities. We conclude that Lyα radiation pressure severely limits a possible extremely efficient, feedback-free phase of star formation in dense metal-poor clouds.
{"title":"Lyman-α radiation pressure regulates star formation efficiency","authors":"Daniele Manzoni, Andrea Ferrara","doi":"10.1051/0004-6361/202557141","DOIUrl":"https://doi.org/10.1051/0004-6361/202557141","url":null,"abstract":"Order-unity star formation efficiencies (SFE) in early galaxies may explain the overabundance of bright galaxies observed by JWST at high redshift. Here we show that Lyman-<i>α<i/> (Ly<i>α<i/>) radiation pressure limits the gas mass converted into stars, particularly in primordial environments. We have developed a shell model including Ly<i>α<i/> feedback, and we validate it with one-dimensional hydrodynamical simulations. To account for Ly<i>α<i/> resonant scattering, we adopted the most recent force multiplier fits, including the effect of Ly<i>α<i/> photon destruction by dust grains. We find that independent of their gas surface density, Σ<sub><i>g<i/><sub/>, clouds are disrupted on a timescale shorter than the free-fall time and even before supernova explosions if . At log(<i>Z<i/>/<i>Z<i/><sub>⊙<sub/>) = − 2, which is relevant for high-redshift galaxies, the SFE is for . The SFE is even lower for decreasing metallicity. Bursts of star formation with near-unity SFEs are possible only for extreme surface densities, , and near-solar metallicities. We conclude that Ly<i>α<i/> radiation pressure severely limits a possible extremely efficient, feedback-free phase of star formation in dense metal-poor clouds.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711529","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 : 2025-12-10DOI: 10.1051/0004-6361/202555267
Yongmin Yoon, Yongjung Kim, Dohyeong Kim, Kyungwon Chun, Woowon Byun
We examine the connection between galaxy mergers and the triggering of active galactic nuclei (AGNs) using a sample of 614 type 1 AGNs at z < 0.07, along with a control sample of inactive galaxies matched to the AGNs for comparison. We used tidal features, detected in deep images from the DESI Legacy Imaging Survey, as direct evidence of recent mergers. We find that the fraction of type 1 AGN hosts with tidal features (fT) is higher for AGNs with higher luminosities and (to a lesser extent) more massive black holes. Specifically, fT rapidly increases from 0.05 ± 0.03 to 0.75 ± 0.13 as the luminosity of the [O III] λ5007 emission line (L[O III]), an indicator for bolometric AGN luminosity, increases in the range 1039.5 ≲ L[O III]/(erg s−1) ≲ 1042.5. In addition, fT increases from 0.13 ± 0.03 to 0.43 ± 0.09 as black hole mass (MBH) increases in the range 106.0 ≲ MBH/M⊙ ≲ 108.5. The fraction fT also increases with the Eddington ratio, although the trend is less significant compared to that with L[O III] and MBH. The excess of fT, defined as the ratio of fT for AGNs to that of their matched inactive counterparts, exhibits similar trends, primarily increasing with L[O III] and weakly with MBH. Our results indicate that, in the local Universe, galaxy mergers are the predominant triggering mechanism for high-luminosity AGNs, whereas they play a lesser role in triggering lower-luminosity AGNs. Additionally, strong events, such as galaxy mergers, may be more necessary to activate massive black holes in more massive galaxies due to their lower gas fractions.
{"title":"Direct observational evidence that higher-luminosity type 1 active galactic nuclei are most commonly triggered by galaxy mergers","authors":"Yongmin Yoon, Yongjung Kim, Dohyeong Kim, Kyungwon Chun, Woowon Byun","doi":"10.1051/0004-6361/202555267","DOIUrl":"https://doi.org/10.1051/0004-6361/202555267","url":null,"abstract":"We examine the connection between galaxy mergers and the triggering of active galactic nuclei (AGNs) using a sample of 614 type 1 AGNs at <i>z<i/> < 0.07, along with a control sample of inactive galaxies matched to the AGNs for comparison. We used tidal features, detected in deep images from the DESI Legacy Imaging Survey, as direct evidence of recent mergers. We find that the fraction of type 1 AGN hosts with tidal features (<i>f<i/><sub>T<sub/>) is higher for AGNs with higher luminosities and (to a lesser extent) more massive black holes. Specifically, <i>f<i/><sub>T<sub/> rapidly increases from 0.05 ± 0.03 to 0.75 ± 0.13 as the luminosity of the [O III] <i>λ<i/>5007 emission line (<i>L<i/><sub>[O III]<sub/>), an indicator for bolometric AGN luminosity, increases in the range 10<sup>39.5<sup/> ≲ <i>L<i/><sub>[O III]<sub/>/(erg s<sup>−1<sup/>) ≲ 10<sup>42.5<sup/>. In addition, <i>f<i/><sub>T<sub/> increases from 0.13 ± 0.03 to 0.43 ± 0.09 as black hole mass (<i>M<i/><sub>BH<sub/>) increases in the range 10<sup>6.0<sup/> ≲ <i>M<i/><sub>BH<sub/>/<i>M<i/><sub>⊙<sub/> ≲ 10<sup>8.5<sup/>. The fraction <i>f<i/><sub>T<sub/> also increases with the Eddington ratio, although the trend is less significant compared to that with <i>L<i/><sub>[O III]<sub/> and <i>M<i/><sub>BH<sub/>. The excess of <i>f<i/><sub>T<sub/>, defined as the ratio of <i>f<i/><sub>T<sub/> for AGNs to that of their matched inactive counterparts, exhibits similar trends, primarily increasing with <i>L<i/><sub>[O III]<sub/> and weakly with <i>M<i/><sub>BH<sub/>. Our results indicate that, in the local Universe, galaxy mergers are the predominant triggering mechanism for high-luminosity AGNs, whereas they play a lesser role in triggering lower-luminosity AGNs. Additionally, strong events, such as galaxy mergers, may be more necessary to activate massive black holes in more massive galaxies due to their lower gas fractions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711537","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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