Pub Date : 2025-10-24eCollection Date: 2025-12-01DOI: 10.1093/mnras/staf1847
José A Benavides, Laura V Sales, Andrew Wetzel, Jorge Moreno, Robert Feldmann, Francisco J Mercado, James S Bullock, Philip F Hopkins, Claude-André Faucher-Giguère, Jonathan Stern, Coral Wheeler, Dušan Kereš
We study the morphology of hundreds of simulated central galaxies in the stellar mass range [Formula: see text] 107.5-1011 [Formula: see text] from the FIREbox cosmological volume. We demonstrate that FIREbox is able to predict a wide variety of morphologies, spanning from disc-dominated objects to spheroidal galaxies supported by stellar velocity dispersion. However, the simulations predict a strong relation between morphology (degree of rotational support) and stellar mass: galaxies comparable to the Milky Way are often disc-dominated while the presence of stellar discs mostly vanishes for dwarfs with [Formula: see text][Formula: see text]. This defines a 'morphology transition' regime for galaxies with [Formula: see text] in which discs become increasingly common, but below which discs are rare. We show that burstiness in the star formation history and the deepening of the gravitational potential strongly correlate in our simulations with this transition regime, with discs forming in objects with lower levels of burstiness in the last [Formula: see text] Gyr and haloes with mass [Formula: see text] and above. While observations support a transition towards thicker discs in the regime of dwarfs, our results are in partial disagreement with observations of at least some largely rotationally supported gas discs in dwarfs with [Formula: see text][Formula: see text]. This study highlights dwarf morphology as a fundamental benchmark for testing future galaxy formation models.
{"title":"Discs no more: the morphology of low-mass simulated galaxies in FIREbox.","authors":"José A Benavides, Laura V Sales, Andrew Wetzel, Jorge Moreno, Robert Feldmann, Francisco J Mercado, James S Bullock, Philip F Hopkins, Claude-André Faucher-Giguère, Jonathan Stern, Coral Wheeler, Dušan Kereš","doi":"10.1093/mnras/staf1847","DOIUrl":"10.1093/mnras/staf1847","url":null,"abstract":"<p><p>We study the morphology of hundreds of simulated central galaxies in the stellar mass range [Formula: see text] 10<sup>7.5</sup>-10<sup>11</sup> [Formula: see text] from the FIREbox cosmological volume. We demonstrate that FIREbox is able to predict a wide variety of morphologies, spanning from disc-dominated objects to spheroidal galaxies supported by stellar velocity dispersion. However, the simulations predict a strong relation between morphology (degree of rotational support) and stellar mass: galaxies comparable to the Milky Way are often disc-dominated while the presence of stellar discs mostly vanishes for dwarfs with [Formula: see text][Formula: see text]. This defines a 'morphology transition' regime for galaxies with [Formula: see text] in which discs become increasingly common, but below which discs are rare. We show that burstiness in the star formation history and the deepening of the gravitational potential strongly correlate in our simulations with this transition regime, with discs forming in objects with lower levels of burstiness in the last [Formula: see text] Gyr and haloes with mass [Formula: see text] and above. While observations support a transition towards thicker discs in the regime of dwarfs, our results are in partial disagreement with observations of at least some largely rotationally supported gas discs in dwarfs with [Formula: see text][Formula: see text]. This study highlights dwarf morphology as a fundamental benchmark for testing future galaxy formation models.</p>","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"544 4","pages":"4651-4664"},"PeriodicalIF":4.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12680306/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145701393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15eCollection Date: 2024-12-01DOI: 10.1093/mnras/stae2588
Vincent J Esposito, Salma Bejaoui, Brant E Billinghurst, Christiaan Boersma, Ryan C Fortenberry, Farid Salama
Strong anharmonic coupling between vibrational states in polycyclic aromatic hydrocarbons (PAH) produces highly mixed vibrational transitions that challenge the current understanding of the nature of the astronomical mid-infrared PAH emission bands. Traditionally, PAH emission bands have been characterized as either aromatic or aliphatic, and this assignment is used to determine the fraction of aliphatic carbon in astronomical sources. In reality, each of the transitions previously utilized for such an attribution is highly mixed with contributions from both aliphatic and aromatic CH motions as well as non-CH motions such as CC stretches. High-resolution gas-phase IR absorption measurements of the spectra of the aromatic molecules indene and 2-ethynyltoluene at the Canadian Light Source combined with high-level anharmonic quantum chemical computations reveal the complex nature of these transitions, implying that the use of these features as a marker for the aliphatic fraction in astronomical sources is not uniquely true or actually predictive. Further, the presence of aliphatic, aromatic, and ethynyl CH groups in 2-ethynyltoluene provides an internally consistent opportunity to simultaneously study the spectroscopy of all three astronomically important groups. Finally, this study makes an explicit connection between fundamental quantum mechanical principles and macroscopic astronomical chemical physics, an important link necessary to untangle the lifecycle of stellar and planetary systems.
{"title":"Battle of the CH motions: aliphatic versus aromatic contributions to astronomical PAH emission and exploration of the aliphatic, aromatic, and ethynyl CH stretches.","authors":"Vincent J Esposito, Salma Bejaoui, Brant E Billinghurst, Christiaan Boersma, Ryan C Fortenberry, Farid Salama","doi":"10.1093/mnras/stae2588","DOIUrl":"10.1093/mnras/stae2588","url":null,"abstract":"<p><p>Strong anharmonic coupling between vibrational states in polycyclic aromatic hydrocarbons (PAH) produces highly mixed vibrational transitions that challenge the current understanding of the nature of the astronomical mid-infrared PAH emission bands. Traditionally, PAH emission bands have been characterized as either aromatic or aliphatic, and this assignment is used to determine the fraction of aliphatic carbon in astronomical sources. In reality, each of the transitions previously utilized for such an attribution is highly mixed with contributions from both aliphatic and aromatic CH motions as well as non-CH motions such as CC stretches. High-resolution gas-phase IR absorption measurements of the spectra of the aromatic molecules indene and 2-ethynyltoluene at the Canadian Light Source combined with high-level anharmonic quantum chemical computations reveal the complex nature of these transitions, implying that the use of these features as a marker for the aliphatic fraction in astronomical sources is not uniquely true or actually predictive. Further, the presence of aliphatic, aromatic, and ethynyl CH groups in 2-ethynyltoluene provides an internally consistent opportunity to simultaneously study the spectroscopy of all three astronomically important groups. Finally, this study makes an explicit connection between fundamental quantum mechanical principles and macroscopic astronomical chemical physics, an important link necessary to untangle the lifecycle of stellar and planetary systems.</p>","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"535 4","pages":"3239-3251"},"PeriodicalIF":4.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11630826/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142812957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2023-06-27DOI: 10.1177/17585732231185099
Nur Canbolat, Serkan Bayram, Yaşar Samet Gökçeoğlu, Okan Tezgel, Mehmet Kapicioğlu, Ali Erşen, Kerem Bilsel, Mehmet İlke Büget
Background: We aimed to evaluate the predictive determitants in patients with PHF who were treated with reverse shoulder arthroplasty (RSA) by evaluating the patient characteristics and comorbidities and extensive preoperative laboratory parameters.
Methods: With examining the records of elderly patients (over 65 years old) with PHF, who were admitted to our emergency department between 2009 and 2020. For evaluation of the survival, we performed Kaplan-Meirer statistical anaylses. A Cox algorithms (uni and multivariate) were applied to recognize factors (including clinical and laboratory parameters) which are associated with survival.
Results: Sixty-three females and 17 males were included with a mean of 73.5 ± 7.4 years of age. Nineteen (23.83%) patients had decreased after the surgery, with a mean survival of 47.5 ± 32.7 months. There were 61 (76.3%) surviving patients with a mean survival of 67.4 ± 35.4 months. Survival rates in the first 6 months (n: 2 patients), first year (n: 3 patients), and second year (n: 6 patients) after surgery were 97.5%, 96.3%, and 92.3%, respectively.
Conclusion: The age and preoperative hemoglobin level were independently related with poor survival in patients with PHF.
Level of evidence: Level III Retrospective Cohort, Prognosis Study.
{"title":"Predictive prognostic factors in patients with proximal humeral fracture treated with reverse shoulder arthroplasty.","authors":"Nur Canbolat, Serkan Bayram, Yaşar Samet Gökçeoğlu, Okan Tezgel, Mehmet Kapicioğlu, Ali Erşen, Kerem Bilsel, Mehmet İlke Büget","doi":"10.1177/17585732231185099","DOIUrl":"10.1177/17585732231185099","url":null,"abstract":"<p><strong>Background: </strong>We aimed to evaluate the predictive determitants in patients with PHF who were treated with reverse shoulder arthroplasty (RSA) by evaluating the patient characteristics and comorbidities and extensive preoperative laboratory parameters.</p><p><strong>Methods: </strong>With examining the records of elderly patients (over 65 years old) with PHF, who were admitted to our emergency department between 2009 and 2020. For evaluation of the survival, we performed Kaplan-Meirer statistical anaylses. A Cox algorithms (uni and multivariate) were applied to recognize factors (including clinical and laboratory parameters) which are associated with survival.</p><p><strong>Results: </strong>Sixty-three females and 17 males were included with a mean of 73.5 ± 7.4 years of age. Nineteen (23.83%) patients had decreased after the surgery, with a mean survival of 47.5 ± 32.7 months<b>.</b> There were 61 (76.3%) surviving patients with a mean survival of 67.4 ± 35.4 months. Survival rates in the first 6 months (n: 2 patients), first year (n: 3 patients), and second year (n: 6 patients) after surgery were 97.5%, 96.3%, and 92.3%, respectively.</p><p><strong>Conclusion: </strong>The age and preoperative hemoglobin level were independently related with poor survival in patients with PHF.</p><p><strong>Level of evidence: </strong>Level III Retrospective Cohort, Prognosis Study.</p>","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"339 1","pages":"518-526"},"PeriodicalIF":4.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11514117/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79740666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Over the past twenty years, there has been increasing evidence of the existence of sausage waves in the solar atmosphere. These observations make them useful tools in the context of atmospheric seismology. Here, we study sausage magnetohydrodynamic waves in a magnetic flux tube of non-zero plasma beta with a circular cross-section and a radially inhomogeneous plasma density. Solving numerically the equations of motion for an initial value problem, the spatio-temporal evolution of the velocity perturbations is obtained for different sets of parameters. We show that the ratio of the amplitudes of the longitudinal and radial perturbations is determined by the amount of plasma beta. Additionally, the longitudinal component of the velocity perturbation experiences phase-mixing within a layer surrounding the boundary of the flux tube with a rate depending on the amount of plasma beta. The results revealed that in the presence of a non-zero plasma beta, the flux tube exhibits oscillations in both the radial and longitudinal directions, characterized by a combination of two frequencies: one belonging to the slow continuum and the other to the Alfvén continuum. Also, the period of radial oscillation is obtained for different sets of parameters. The dependence of the period of the radial oscillation on the wavenumber confirms the results obtained in previous studies.
{"title":"On the sausage magnetohydrodynamic waves in magnetic flux tubes: finite plasma beta and phase mixing","authors":"Zanyar Ebrahimi","doi":"10.1093/mnras/stae2173","DOIUrl":"https://doi.org/10.1093/mnras/stae2173","url":null,"abstract":"Over the past twenty years, there has been increasing evidence of the existence of sausage waves in the solar atmosphere. These observations make them useful tools in the context of atmospheric seismology. Here, we study sausage magnetohydrodynamic waves in a magnetic flux tube of non-zero plasma beta with a circular cross-section and a radially inhomogeneous plasma density. Solving numerically the equations of motion for an initial value problem, the spatio-temporal evolution of the velocity perturbations is obtained for different sets of parameters. We show that the ratio of the amplitudes of the longitudinal and radial perturbations is determined by the amount of plasma beta. Additionally, the longitudinal component of the velocity perturbation experiences phase-mixing within a layer surrounding the boundary of the flux tube with a rate depending on the amount of plasma beta. The results revealed that in the presence of a non-zero plasma beta, the flux tube exhibits oscillations in both the radial and longitudinal directions, characterized by a combination of two frequencies: one belonging to the slow continuum and the other to the Alfvén continuum. Also, the period of radial oscillation is obtained for different sets of parameters. The dependence of the period of the radial oscillation on the wavenumber confirms the results obtained in previous studies.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"7 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
T M Gaudin, M J Coe, J A Kennea, I M Monageng, D A H Buckley, A Udalski, P A Evans
CXOU J005245.0-722844 is an X-ray source in the Small Magellanic Cloud (SMC) that has long been known as a Be/X-ray binary (BeXRB) star, containing an OBe main sequence star and a compact object. In this paper, we report on a new very fast X-ray outburst from CXOU J005245.0-722844. X-ray observations taken by Swift constrain the duration of the outburst to less than 16 days and find that the source reached super-Eddington X-ray luminosities during the initial phases of the eruption. The XRT spectrum of CXOU J005245.0-722844 during this outburst reveals a super-soft X-ray source, best fit by an absorbed thermal blackbody model. Optical and Ultraviolet follow-up observations from the Optical Gravitational Lensing Experiment (OGLE), Asteroid Terrestrial-impact Last Alert System (ATLAS), and Swift identify a brief ∼0.5 magnitude optical burst coincident with the X-ray outburst that lasted for less than 7 days. Optical photometry additionally identifies the orbital period of the system to be 17.55 days and identifies a shortening of the period to 17.14 days in the years leading up to the outburst. Optical spectroscopy from the Southern African Large Telescope (SALT) confirms that the optical companion is an early-type OBe star. We conclude from our observations that the compact object in this system is a white dwarf (WD), making this the seventh candidate Be/WD X-ray binary. The X-ray outburst is found to be the result of a very-fast, ultra-luminous nova similar to the outburst of MAXI J0158-744.
CXOU J005245.0-722844是小麦哲伦云（SMC）中的一个X射线源，长期以来一直被认为是一颗Be/X射线双星（BeXRB），其中包含一颗OBe主序星和一颗紧凑天体。在本文中，我们报告了来自 CXOU J005245.0-722844 的新的极快 X 射线爆发。由 Swift 拍摄的 X 射线观测数据将爆发持续时间限制在 16 天以内，并发现该星源在爆发初期达到了超爱丁顿 X 射线光度。这次爆发期间 CXOU J005245.0-722844 的 XRT 光谱显示出一个超软 X 射线源，与吸收热黑体模型的拟合效果最佳。来自光学引力透镜实验（OGLE）、小行星地面撞击最后警报系统（ATLAS）和雨燕的光学和紫外线跟踪观测发现，在X射线爆发的同时，还发生了一次持续时间不到7天的∼0.5等的短暂光学爆发。光学测光还确定了该系统的轨道周期为 17.55 天，并确定在爆发前的几年里，该周期缩短到了 17.14 天。南部非洲大型望远镜（SALT）的光学光谱分析证实，这颗光学伴星是一颗早期型 OBe 星。我们通过观测得出结论，这个系统中的紧凑天体是一颗白矮星（WD），这也是第七颗候选的Be/WD X射线双星。我们发现X射线爆发是一个极快的超亮新星爆发的结果，类似于MAXI J0158-744的爆发。
{"title":"CXOU J005245.0-722844: Discovery of a be star / white dwarf binary system in the SMC via a very fast, super-eddington X-ray outburst event","authors":"T M Gaudin, M J Coe, J A Kennea, I M Monageng, D A H Buckley, A Udalski, P A Evans","doi":"10.1093/mnras/stae2176","DOIUrl":"https://doi.org/10.1093/mnras/stae2176","url":null,"abstract":"CXOU J005245.0-722844 is an X-ray source in the Small Magellanic Cloud (SMC) that has long been known as a Be/X-ray binary (BeXRB) star, containing an OBe main sequence star and a compact object. In this paper, we report on a new very fast X-ray outburst from CXOU J005245.0-722844. X-ray observations taken by Swift constrain the duration of the outburst to less than 16 days and find that the source reached super-Eddington X-ray luminosities during the initial phases of the eruption. The XRT spectrum of CXOU J005245.0-722844 during this outburst reveals a super-soft X-ray source, best fit by an absorbed thermal blackbody model. Optical and Ultraviolet follow-up observations from the Optical Gravitational Lensing Experiment (OGLE), Asteroid Terrestrial-impact Last Alert System (ATLAS), and Swift identify a brief ∼0.5 magnitude optical burst coincident with the X-ray outburst that lasted for less than 7 days. Optical photometry additionally identifies the orbital period of the system to be 17.55 days and identifies a shortening of the period to 17.14 days in the years leading up to the outburst. Optical spectroscopy from the Southern African Large Telescope (SALT) confirms that the optical companion is an early-type OBe star. We conclude from our observations that the compact object in this system is a white dwarf (WD), making this the seventh candidate Be/WD X-ray binary. The X-ray outburst is found to be the result of a very-fast, ultra-luminous nova similar to the outburst of MAXI J0158-744.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"28 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Millisecond magnetars are widely suggested as the central engines powering hydrogen-poor superluminous supernovae (SLSNe). These magnetars primarily lose huge rotational energy through gravitational wave radiation (GWR) and magnetic dipole radiation (MDR), with MDR serving as an energy source for SLSNe. We study the evolution of the magnetar spin, magnetic inclination angle, and the resulting thermal radiative luminosity of the SLSNe, where the impacts of the nucleon-nucleon short-range correlation, the mass and initial spin of the magnetar, and the density-dependent symmetry energy of the dense nuclear matter on the evolution are discussed. The relativistic mean-field theory is employed to calculate the nuclear matter properties, and we particularly concentrate on the time- and space-dependent bulk viscosity which is crucial for the magnetic inclination angle evolution. It is found that the nucleon-nucleon short-range correlation weakens the damping of bulk viscosity of dense matter and therefore inhibits the growth of magnetic inclination angle, and it reduces the MDR (GWR) peak luminosity of a canonical magnetar by several times while it raises the peak thermal radiation luminosity of SLSNe by several times. For magnetars with nonrotating mass obviously lower than the $1.4 , rm M_odot$ with slow initial rotation, the magnetic inclination angle is more likely to evolve towards 0 degrees quickly, and these magnetars are not suitable as the central engine for SLSNe. Within the ‘family’ of FSUGarnet interaction, a stiffer symmetry energy gives a lower threshold of direct Urca process and hence gives a much larger bulk viscosity coefficient, and thus it promotes the growth of the magnetic inclination angle and the GWR for canonical stars but reduces the peak brightness of SLSNe significantly.
{"title":"Effects of nucleon-nucleon short-range correlation and symmetry energy on the evolution of newly born magnetars","authors":"C X Liu, T F Feng, J M Dong","doi":"10.1093/mnras/stae2170","DOIUrl":"https://doi.org/10.1093/mnras/stae2170","url":null,"abstract":"Millisecond magnetars are widely suggested as the central engines powering hydrogen-poor superluminous supernovae (SLSNe). These magnetars primarily lose huge rotational energy through gravitational wave radiation (GWR) and magnetic dipole radiation (MDR), with MDR serving as an energy source for SLSNe. We study the evolution of the magnetar spin, magnetic inclination angle, and the resulting thermal radiative luminosity of the SLSNe, where the impacts of the nucleon-nucleon short-range correlation, the mass and initial spin of the magnetar, and the density-dependent symmetry energy of the dense nuclear matter on the evolution are discussed. The relativistic mean-field theory is employed to calculate the nuclear matter properties, and we particularly concentrate on the time- and space-dependent bulk viscosity which is crucial for the magnetic inclination angle evolution. It is found that the nucleon-nucleon short-range correlation weakens the damping of bulk viscosity of dense matter and therefore inhibits the growth of magnetic inclination angle, and it reduces the MDR (GWR) peak luminosity of a canonical magnetar by several times while it raises the peak thermal radiation luminosity of SLSNe by several times. For magnetars with nonrotating mass obviously lower than the $1.4 , rm M_odot$ with slow initial rotation, the magnetic inclination angle is more likely to evolve towards 0 degrees quickly, and these magnetars are not suitable as the central engine for SLSNe. Within the ‘family’ of FSUGarnet interaction, a stiffer symmetry energy gives a lower threshold of direct Urca process and hence gives a much larger bulk viscosity coefficient, and thus it promotes the growth of the magnetic inclination angle and the GWR for canonical stars but reduces the peak brightness of SLSNe significantly.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"1 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Sergio Sánchez-Sanjuán, Jesús Hernández, Ángeles Pérez-Villegas, Carlos Román-Zúñiga, Luis Aguilar, Javier Ballesteros-Paredes, Andrea Bonilla-Barroso
In this work, we analysed young stellar clusters with spatial and kinematic coherence in the Orion star-forming complex. For this study, we selected a sample of pre-main sequence candidates using parallaxes, proper motions and positions on the colour-magnitude diagram. After applying a hierarchical clustering algorithm in the 5D parameter space provided by Gaia DR3, we divided the recovered clusters into two regimes: Big Structures and Small Structures, defined by the number of detected stars per cluster. In the first regime, we found 13 stellar groups distributed along the declination axis in the regions where there is a high density of stars. In the second regime, we recovered 34 clusters classified into two types: 14 as small groups completely independent from the larger structures, including four candidates of new clusters, and 12 classified as sub-structures embedded within five larger clusters. Additionally, radial velocity data from APOGEE-2 and GALAH DR3 was included to study the phase space in some regions of the Orion complex. From the Big Structure regime, we found evidence of a general expansion in the Orion OB1 association over a common centre, giving a clue about the dynamical effects the region is undergoing. Likewise, in the Small Structure regime, the projected kinematics shows the ballistic expansion in the λ Orionis association and the detection of likely events of clusters’ close encounters in the OB1 association.
{"title":"Kinematic study of the orion complex: Analysing the young stellar clusters from big and small structures","authors":"Sergio Sánchez-Sanjuán, Jesús Hernández, Ángeles Pérez-Villegas, Carlos Román-Zúñiga, Luis Aguilar, Javier Ballesteros-Paredes, Andrea Bonilla-Barroso","doi":"10.1093/mnras/stae2157","DOIUrl":"https://doi.org/10.1093/mnras/stae2157","url":null,"abstract":"In this work, we analysed young stellar clusters with spatial and kinematic coherence in the Orion star-forming complex. For this study, we selected a sample of pre-main sequence candidates using parallaxes, proper motions and positions on the colour-magnitude diagram. After applying a hierarchical clustering algorithm in the 5D parameter space provided by Gaia DR3, we divided the recovered clusters into two regimes: Big Structures and Small Structures, defined by the number of detected stars per cluster. In the first regime, we found 13 stellar groups distributed along the declination axis in the regions where there is a high density of stars. In the second regime, we recovered 34 clusters classified into two types: 14 as small groups completely independent from the larger structures, including four candidates of new clusters, and 12 classified as sub-structures embedded within five larger clusters. Additionally, radial velocity data from APOGEE-2 and GALAH DR3 was included to study the phase space in some regions of the Orion complex. From the Big Structure regime, we found evidence of a general expansion in the Orion OB1 association over a common centre, giving a clue about the dynamical effects the region is undergoing. Likewise, in the Small Structure regime, the projected kinematics shows the ballistic expansion in the λ Orionis association and the detection of likely events of clusters’ close encounters in the OB1 association.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"7 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Sahl Rowther, Daniel J Price, Christophe Pinte, Rebecca Nealon, Farzana Meru, Richard Alexander
Irradiation from the central star controls the temperature structure in protoplanetary discs. Yet simulations of gravitational instability typically use models of stellar irradiation with varying complexity, or ignore it altogether, assuming heat generated by spiral shocks is balanced by cooling, leading to a self-regulated state. In this paper, we perform simulations of irradiated, gravitationally unstable protoplanetary discs using 3D hydrodynamics coupled with live Monte-Carlo radiative transfer. We find that the resulting temperature profile is approximately constant in time, since the thermal effects of the star dominate. Hence, the disc cannot regulate gravitational instabilities by adjusting the temperatures in the disc. In a 0.1M⊙ disc, the disc instead adjusts by angular momentum transport induced by the spiral arms, leading to steadily decreasing surface density, and hence quenching of the instability. Thus, strong spiral arms caused by self-gravity would not persist for longer than ten thousand years in the absence of fresh infall, although weak spiral structures remain present over longer timescales. Using synthetic images at 1.3mm, we find that spirals formed in irradiated discs are challenging to detect. In higher mass discs, we find that fragmentation is likely because the dominant stellar irradiation overwhelms the stabilising influence of PdV work and shock heating in the spiral arms.
{"title":"Short-lived gravitational instability in isolated irradiated discs","authors":"Sahl Rowther, Daniel J Price, Christophe Pinte, Rebecca Nealon, Farzana Meru, Richard Alexander","doi":"10.1093/mnras/stae2167","DOIUrl":"https://doi.org/10.1093/mnras/stae2167","url":null,"abstract":"Irradiation from the central star controls the temperature structure in protoplanetary discs. Yet simulations of gravitational instability typically use models of stellar irradiation with varying complexity, or ignore it altogether, assuming heat generated by spiral shocks is balanced by cooling, leading to a self-regulated state. In this paper, we perform simulations of irradiated, gravitationally unstable protoplanetary discs using 3D hydrodynamics coupled with live Monte-Carlo radiative transfer. We find that the resulting temperature profile is approximately constant in time, since the thermal effects of the star dominate. Hence, the disc cannot regulate gravitational instabilities by adjusting the temperatures in the disc. In a 0.1M⊙ disc, the disc instead adjusts by angular momentum transport induced by the spiral arms, leading to steadily decreasing surface density, and hence quenching of the instability. Thus, strong spiral arms caused by self-gravity would not persist for longer than ten thousand years in the absence of fresh infall, although weak spiral structures remain present over longer timescales. Using synthetic images at 1.3mm, we find that spirals formed in irradiated discs are challenging to detect. In higher mass discs, we find that fragmentation is likely because the dominant stellar irradiation overwhelms the stabilising influence of PdV work and shock heating in the spiral arms.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"44 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Phosphorous species are of great interest in interstellar chemistry since they are the basic blocks for building life here on Earth. Modelling the abundance and environment of recently detected PO+ under non Local Thermodynamic Equilibrium (LTE) requires rotational spectra of the molecule along with accurate collisional rates with the most abundant species, hydrogen and helium. A new 4D ab initio potential energy surface (PES) of PO+ - H2 collision is calculated using CCSD(T)/CBS(DTQ) methodology considering rigid rotor approximation. The region containing the minima of the PES is augmented using neural networks (NN) model while very high potentials (>2500 cm−1) and asymptotic region have been approximated using Slater and R−4 functions respectively. The close coupling calculations have been performed using MOLSCAT software for both ortho and para-H2. The rate coefficients have been reported for transitions j − j′ = 1 − 0, 2 − 1, 3 − 2 and 5 − 4 through which PO+ has been experimentally detected in ISM. The rate coefficients for even and odd transitions of PO+ with para-H2 are compared with that of helium and are found to be 1.1-2.0 times higher. For even transitions (Δj = 2), the ortho-H2 rates are 10% higher than para-H2 rates. However, the trend reverses in the case of odd transitions (Δj = 1) when higher J transitions are considered at low temperatures. At higher temperatures, the ortho rates cross the para-H2 rates and become larger than the latter. The new rate coefficients with both ortho and para-H2 will enable accurate modelling of the PO+ abundance in the interstellar medium under non-LTE conditions.
{"title":"Inelastic scattering of PO+ by H2 at interstellar temperatures","authors":"Pooja Chahal, Apoorv Kushwaha, T J Dhilip Kumar","doi":"10.1093/mnras/stae2166","DOIUrl":"https://doi.org/10.1093/mnras/stae2166","url":null,"abstract":"Phosphorous species are of great interest in interstellar chemistry since they are the basic blocks for building life here on Earth. Modelling the abundance and environment of recently detected PO+ under non Local Thermodynamic Equilibrium (LTE) requires rotational spectra of the molecule along with accurate collisional rates with the most abundant species, hydrogen and helium. A new 4D ab initio potential energy surface (PES) of PO+ - H2 collision is calculated using CCSD(T)/CBS(DTQ) methodology considering rigid rotor approximation. The region containing the minima of the PES is augmented using neural networks (NN) model while very high potentials (&gt;2500 cm−1) and asymptotic region have been approximated using Slater and R−4 functions respectively. The close coupling calculations have been performed using MOLSCAT software for both ortho and para-H2. The rate coefficients have been reported for transitions j − j′ = 1 − 0, 2 − 1, 3 − 2 and 5 − 4 through which PO+ has been experimentally detected in ISM. The rate coefficients for even and odd transitions of PO+ with para-H2 are compared with that of helium and are found to be 1.1-2.0 times higher. For even transitions (Δj = 2), the ortho-H2 rates are 10% higher than para-H2 rates. However, the trend reverses in the case of odd transitions (Δj = 1) when higher J transitions are considered at low temperatures. At higher temperatures, the ortho rates cross the para-H2 rates and become larger than the latter. The new rate coefficients with both ortho and para-H2 will enable accurate modelling of the PO+ abundance in the interstellar medium under non-LTE conditions.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"4 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Population III stars are characterized by extremely low metallicities as they are thought to be formed from a pristine gas in the early Universe. Although the existence of Population III stars is widely accepted, the lack of direct observational evidence hampers the study of the nature of the putative stars. In this article, we explore the possibilities of constraining the nature of the oldest stars by using the luminosity function of their remnants – white dwarfs. We study the formation and evolution of white dwarf populations by following star formation in a Milky Way-like galaxy using the semi-analytic model a-sloth. We derive the white dwarf luminosity function by applying a linear Initial-Final Mass Relation and Mestel’s cooling model. The obtained luminosity function is generally in agreement with available observations and theoretical predictions – with an exponential increase to a maximum of Mabs = 16 and a sudden drop for Mabs > 16. We explore the uncertainties of our model and compare them to the observational estimates. We adopt two different models of the initial mass function of Population III stars to show that the faint end of the luminosity function imprints the signature of Population III remnants. If the feature is detected in future observations, it would provide a clue to Population III stars and would also be an indirect evidence of low- to intermediate-mass Population III stars. We discuss the challenges and prospects for detecting the signatures.
{"title":"The imprint of the first stars on the faint end of the white dwarf luminosity function","authors":"Bartosz Dzięcioł, Tilman Hartwig, Naoki Yoshida","doi":"10.1093/mnras/stae2172","DOIUrl":"https://doi.org/10.1093/mnras/stae2172","url":null,"abstract":"Population III stars are characterized by extremely low metallicities as they are thought to be formed from a pristine gas in the early Universe. Although the existence of Population III stars is widely accepted, the lack of direct observational evidence hampers the study of the nature of the putative stars. In this article, we explore the possibilities of constraining the nature of the oldest stars by using the luminosity function of their remnants – white dwarfs. We study the formation and evolution of white dwarf populations by following star formation in a Milky Way-like galaxy using the semi-analytic model a-sloth. We derive the white dwarf luminosity function by applying a linear Initial-Final Mass Relation and Mestel’s cooling model. The obtained luminosity function is generally in agreement with available observations and theoretical predictions – with an exponential increase to a maximum of Mabs = 16 and a sudden drop for Mabs &gt; 16. We explore the uncertainties of our model and compare them to the observational estimates. We adopt two different models of the initial mass function of Population III stars to show that the faint end of the luminosity function imprints the signature of Population III remnants. If the feature is detected in future observations, it would provide a clue to Population III stars and would also be an indirect evidence of low- to intermediate-mass Population III stars. We discuss the challenges and prospects for detecting the signatures.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"32 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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