Pub Date : 2024-08-27DOI: 10.1051/0004-6361/202449762
S. A. Tyul’bashev, M. A. Kitaeva, D. V. Pervoukhin, G. E. Tyul’basheva, E. A. Brylyakova, A. V. Chernosov, I. L. Ovchinnikov
The search for rotating radio transients (RRATs) was carried out at a frequency of 111 MHz, as daily observations carried out on the Large Phased Array (LPA) radio telescope at declinations of −9° < δ < +42°. Overall, 19 new RRATs were discovered for dispersion measures (DMs) from 2.5 to 72.6 pc cm−3. Estimates of the periods were obtained for three RRATs, with two of them (J0408+28; J0440+35) located at distances of 134 and 136 pc from Sun, placing them among the closest of all known RRATs.
{"title":"Search for rotating radio transients in three years of monitoring data","authors":"S. A. Tyul’bashev, M. A. Kitaeva, D. V. Pervoukhin, G. E. Tyul’basheva, E. A. Brylyakova, A. V. Chernosov, I. L. Ovchinnikov","doi":"10.1051/0004-6361/202449762","DOIUrl":"https://doi.org/10.1051/0004-6361/202449762","url":null,"abstract":"The search for rotating radio transients (RRATs) was carried out at a frequency of 111 MHz, as daily observations carried out on the Large Phased Array (LPA) radio telescope at declinations of −9° < <i>δ <<i/> +42°. Overall, 19 new RRATs were discovered for dispersion measures (DMs) from 2.5 to 72.6 pc cm<sup>−3<sup/>. Estimates of the periods were obtained for three RRATs, with two of them (J0408+28; J0440+35) located at distances of 134 and 136 pc from Sun, placing them among the closest of all known RRATs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142085009","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 : 2024-08-23DOI: 10.1051/0004-6361/202451370
Bert Vander Meulen, Peter Camps, Masahiro Tsujimoto, Keiichi Wada
Context. X-ray microcalorimeter instruments are expected to spectrally resolve the intrinsic line shapes of the strongest fluorescent lines. X-ray models should therefore incorporate these intrinsic line profiles to obtain meaningful constraints from observational data.Aims. We included the intrinsic line profiles of the strongest fluorescent lines in the X-ray radiative transfer code SKIRT to model the cold-gas structure and kinematics based on high-resolution line observations from XRISM/Resolve and Athena/X-IFU.Methods. The intrinsic line profiles of the Kα and Kβ lines of Cr, Mn, Fe, Co, Ni, and Cu were implemented based on a multi-Lorentzian parameterisation. Line energies are sampled from these Lorentzian components during the radiative transfer routine.Results. In the optically thin regime, the SKIRT results match the intrinsic line profiles as measured in the laboratory. With a more complex 3D model that also includes kinematics, we find that the intrinsic line profiles are broadened and shifted to an extent that will be detectable with XRISM/Resolve; this model also demonstrates the importance of the intrinsic line shapes for constraining kinematics. We find that observed line profiles directly trace the cold-gas kinematics, without any additional radiative transfer effects.Conclusions. With the advent of the first XRISM/Resolve data, this update to the X-ray radiative transfer framework of SKIRT is timely and provides a unique tool for constraining the velocity structure of cold gas from X-ray microcalorimeter spectra.
背景X 射线微量热计仪器有望从光谱上解析最强荧光线的固有线形。因此，X 射线模型应包含这些固有线剖面，以便从观测数据中获得有意义的约束。我们根据 XRISM/Resolve 和 Athena/X-IFU 的高分辨率线观测数据，将最强荧光线的本征线剖面纳入 X 射线辐射传递代码 SKIRT，以建立冷气体结构和运动学模型。铬、锰、铁、钴、镍和铜的 Kα 和 Kβ 线的固有线剖面是在多洛伦兹参数化的基础上实现的。在辐射传递过程中，从这些洛伦兹成分中采样线能量。在光学稀薄区，SKIRT 的结果与实验室测量的固有线剖面相吻合。通过一个更复杂的三维模型（也包括运动学），我们发现固有线剖面被拓宽和偏移，其程度可以用 XRISM/Resolve 检测到；这个模型也证明了固有线形状对于约束运动学的重要性。我们发现，观测到的线剖面可以直接追踪冷气体运动学，而不需要任何额外的辐射传递效应。随着第一批 XRISM/Resolve 数据的出现，对 SKIRT 的 X 射线辐射传递框架的更新非常及时，它为从 X 射线微量热计光谱中约束冷气体的速度结构提供了一个独特的工具。
{"title":"Intrinsic line profiles for X-ray fluorescent lines in SKIRT","authors":"Bert Vander Meulen, Peter Camps, Masahiro Tsujimoto, Keiichi Wada","doi":"10.1051/0004-6361/202451370","DOIUrl":"https://doi.org/10.1051/0004-6361/202451370","url":null,"abstract":"<i>Context.<i/> X-ray microcalorimeter instruments are expected to spectrally resolve the intrinsic line shapes of the strongest fluorescent lines. X-ray models should therefore incorporate these intrinsic line profiles to obtain meaningful constraints from observational data.<i>Aims.<i/> We included the intrinsic line profiles of the strongest fluorescent lines in the X-ray radiative transfer code SKIRT to model the cold-gas structure and kinematics based on high-resolution line observations from XRISM/Resolve and <i>Athena<i/>/X-IFU.<i>Methods.<i/> The intrinsic line profiles of the K<i>α<i/> and K<i>β<i/> lines of Cr, Mn, Fe, Co, Ni, and Cu were implemented based on a multi-Lorentzian parameterisation. Line energies are sampled from these Lorentzian components during the radiative transfer routine.<i>Results.<i/> In the optically thin regime, the SKIRT results match the intrinsic line profiles as measured in the laboratory. With a more complex 3D model that also includes kinematics, we find that the intrinsic line profiles are broadened and shifted to an extent that will be detectable with XRISM/Resolve; this model also demonstrates the importance of the intrinsic line shapes for constraining kinematics. We find that observed line profiles directly trace the cold-gas kinematics, without any additional radiative transfer effects.<i>Conclusions.<i/> With the advent of the first XRISM/Resolve data, this update to the X-ray radiative transfer framework of SKIRT is timely and provides a unique tool for constraining the velocity structure of cold gas from X-ray microcalorimeter spectra.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142200045","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 : 2024-08-23DOI: 10.1051/0004-6361/202451332
E. Gaidos, H. Parviainen, E. Esparza-Borges, A. Fukui, K. Isogai, K. Kawauchi, J. de Leon, M. Mori, F. Murgas, N. Narita, E. Palle, N. Watanabe
Context. Rocky planets on ultra-short period orbits can have surface magma oceans and rock-vapour atmospheres in which dust can condense. Observations of that dust can inform us about the composition and surface conditions on these objects.Aims. We constrained the properties and long-term (decade) behaviour of the transiting dust cloud from the evaporating planet K2-22b.Methods.We observed K2-22b around 40 predicted transits with MuSCAT ground-based multi-optical channel imagers, and complemented these data with long-term monitoring by the ground-based ATLAS (2018-2024) and space-based TESS (2021–2023) surveys.Results. We detected signals during 7 transits, none of which showed significant wavelength dependence. The expected number of MuSCAT-detected transits is ≥22, indicating a decline in mean transit depth since the K2 discovery observations in 2014.Conclusions. The lack of a significant wavelength dependence indicates that dust grains are large or the cloud is optically thick. Long-term trends of depth could be due to a magnetic cycle on the host star or to overturn of the planet’s dayside surface magma ocean. The possibility that K2-22b is disappearing altogether is ruled out by the stability of the transit ephemeris against non-gravitational forces, which constrains the mass to be at least comparable to Ceres.
{"title":"Climate change in hell: Long-term variation in transits of the evaporating planet K2-22b","authors":"E. Gaidos, H. Parviainen, E. Esparza-Borges, A. Fukui, K. Isogai, K. Kawauchi, J. de Leon, M. Mori, F. Murgas, N. Narita, E. Palle, N. Watanabe","doi":"10.1051/0004-6361/202451332","DOIUrl":"https://doi.org/10.1051/0004-6361/202451332","url":null,"abstract":"<i>Context.<i/> Rocky planets on ultra-short period orbits can have surface magma oceans and rock-vapour atmospheres in which dust can condense. Observations of that dust can inform us about the composition and surface conditions on these objects.<i>Aims.<i/> We constrained the properties and long-term (decade) behaviour of the transiting dust cloud from the evaporating planet K2-22b.<i>Methods.<i/>We observed K2-22b around 40 predicted transits with MuSCAT ground-based multi-optical channel imagers, and complemented these data with long-term monitoring by the ground-based ATLAS (2018-2024) and space-based TESS (2021–2023) surveys.<i>Results.<i/> We detected signals during 7 transits, none of which showed significant wavelength dependence. The expected number of MuSCAT-detected transits is ≥22, indicating a decline in mean transit depth since the <i>K2<i/> discovery observations in 2014.<i>Conclusions.<i/> The lack of a significant wavelength dependence indicates that dust grains are large or the cloud is optically thick. Long-term trends of depth could be due to a magnetic cycle on the host star or to overturn of the planet’s dayside surface magma ocean. The possibility that K2-22b is disappearing altogether is ruled out by the stability of the transit ephemeris against non-gravitational forces, which constrains the mass to be at least comparable to Ceres.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225753","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 : 2024-08-22DOI: 10.1051/0004-6361/202451267
Ismo Tähtinen, Timo Asikainen, Kalevi Mursula
Context. The open solar flux, that is, the total magnetic flux escaping the Sun, is one of the most important parameters connecting solar activity to the Earth. The open solar flux is commonly estimated from photospheric magnetic field measurements by making model assumptions about the solar corona. However, the question in which way the open solar flux is directly related to the distribution of the photospheric magnetic field is still partly unknown.Aims. We aim to reconstruct the open solar flux directly from the photospheric magnetic fields without making any assumptions about the corona and without using coronal hole observations, for instance.Methods. We modified an earlier vector sum method by taking magnetic field polarities into account and applied the method to the synoptic magnetograms of six instruments to determine the open solar flux from solar cycles 21–24.Results. The modified vector sum method produces a vector of the global solar magnetic field whose magnitude closely matches the open solar flux from the potential field source surface (PFSS) model both by the absolute scale and the overall time evolution for each of the six magnetograms. The latitude of this vector follows the Hale cycle by always pointing toward the dominantly positive-polarity hemisphere, and its longitude coincides with the location of the main coronal holes of the McIntosh Archive. We find multi-year periods during which the longitude of the vector slowly drifts or stays rather stationary in the Carrington frame. These periods are punctuated by times when the longitude moves rapidly in the Carrington frame. By comparing the magnitude of this vector to the open solar flux calculated from the PFSS model with different source surface heights, we find that the best match is produced with a source surface height Rss = 2.4 − 2.5 R⊙.
{"title":"Straight outta photosphere: Open solar flux without coronal modeling","authors":"Ismo Tähtinen, Timo Asikainen, Kalevi Mursula","doi":"10.1051/0004-6361/202451267","DOIUrl":"https://doi.org/10.1051/0004-6361/202451267","url":null,"abstract":"<i>Context.<i/> The open solar flux, that is, the total magnetic flux escaping the Sun, is one of the most important parameters connecting solar activity to the Earth. The open solar flux is commonly estimated from photospheric magnetic field measurements by making model assumptions about the solar corona. However, the question in which way the open solar flux is directly related to the distribution of the photospheric magnetic field is still partly unknown.<i>Aims.<i/> We aim to reconstruct the open solar flux directly from the photospheric magnetic fields without making any assumptions about the corona and without using coronal hole observations, for instance.<i>Methods.<i/> We modified an earlier vector sum method by taking magnetic field polarities into account and applied the method to the synoptic magnetograms of six instruments to determine the open solar flux from solar cycles 21–24.<i>Results.<i/> The modified vector sum method produces a vector of the global solar magnetic field whose magnitude closely matches the open solar flux from the potential field source surface (PFSS) model both by the absolute scale and the overall time evolution for each of the six magnetograms. The latitude of this vector follows the Hale cycle by always pointing toward the dominantly positive-polarity hemisphere, and its longitude coincides with the location of the main coronal holes of the McIntosh Archive. We find multi-year periods during which the longitude of the vector slowly drifts or stays rather stationary in the Carrington frame. These periods are punctuated by times when the longitude moves rapidly in the Carrington frame. By comparing the magnitude of this vector to the open solar flux calculated from the PFSS model with different source surface heights, we find that the best match is produced with a source surface height <i>R<i/><sub><i>ss<i/><sub/> = 2.4 − 2.5 <i>R<i/><sub>⊙<sub/>.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142042655","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 : 2024-08-22DOI: 10.1051/0004-6361/202348595
R. Ballhausen, P. Thalhammer, P. Pradhan, E. Sokolova-Lapa, J. Stierhof, K. Pottschmidt, J. Wilms, J. B. Coley, P. Kretschmar, F. Fürst, P. Becker, B. West, C. Malacaria, M. T. Wolff, R. Rothschild, R. Staubert
In 2021, the high-mass X-ray binary EXO 2030+375 underwent a giant X-ray outburst, the first since 2006, that reached a peak flux of ∼600 mCrab (3–50 keV). The goal of this work is to study the spectral evolution over the course of the outburst, search for possible cyclotron resonance scattering features (CRSFs), and to associate spectral components with the emission pattern of the accretion column. We used broadband spectra taken with the Nuclear Spectroscopic Telescope Array (NuSTAR), the Neutron Star Interior Composition Explorer (NICER), and Chandra near the peak and during the decline phase of the outburst. We describe the data with established empirical continuum models and perform pulse-phase-resolved spectroscopy. We compare the spectral evolution with pulse phase using a proposed geometrical emission model. We find a significant spectral hardening toward lower luminosity, a behavior that is expected for super-critical sources. The continuum shape and evolution cannot be described by a simple power-law model with exponential cutoff; it requires additional absorption or emission components. We can confirm the presence of a narrow absorption feature at ∼10 keV in both NuSTAR observations. The absence of harmonics puts into question the interpretation of this feature as a CRSF. The empirical spectral components cannot be directly associated with identified emission components from the accretion column.
{"title":"The giant outburst of EXO 2030+375","authors":"R. Ballhausen, P. Thalhammer, P. Pradhan, E. Sokolova-Lapa, J. Stierhof, K. Pottschmidt, J. Wilms, J. B. Coley, P. Kretschmar, F. Fürst, P. Becker, B. West, C. Malacaria, M. T. Wolff, R. Rothschild, R. Staubert","doi":"10.1051/0004-6361/202348595","DOIUrl":"https://doi.org/10.1051/0004-6361/202348595","url":null,"abstract":"In 2021, the high-mass X-ray binary EXO 2030+375 underwent a giant X-ray outburst, the first since 2006, that reached a peak flux of ∼600 mCrab (3–50 keV). The goal of this work is to study the spectral evolution over the course of the outburst, search for possible cyclotron resonance scattering features (CRSFs), and to associate spectral components with the emission pattern of the accretion column. We used broadband spectra taken with the Nuclear Spectroscopic Telescope Array (<i>NuSTAR<i/>), the Neutron Star Interior Composition Explorer (NICER), and <i>Chandra<i/> near the peak and during the decline phase of the outburst. We describe the data with established empirical continuum models and perform pulse-phase-resolved spectroscopy. We compare the spectral evolution with pulse phase using a proposed geometrical emission model. We find a significant spectral hardening toward lower luminosity, a behavior that is expected for super-critical sources. The continuum shape and evolution cannot be described by a simple power-law model with exponential cutoff; it requires additional absorption or emission components. We can confirm the presence of a narrow absorption feature at ∼10 keV in both <i>NuSTAR<i/> observations. The absence of harmonics puts into question the interpretation of this feature as a CRSF. The empirical spectral components cannot be directly associated with identified emission components from the accretion column.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142042661","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 : 2024-08-22DOI: 10.1051/0004-6361/202348594
P. Thalhammer, R. Ballhausen, E. Sokolova-Lapa, J. Stierhof, A. Zainab, R. Staubert, K. Pottschmidt, J. B. Coley, R. E. Rothschild, G. K. Jaisawal, B. West, P. A. Becker, P. Pradhan, P. Kretschmar, J. Wilms
The Be X-ray binary EXO 2030+375 went through its third recorded giant outburst from June 2021 to early 2022. We present the results of both spectral and timing analysis based on NICER monitoring, covering the 2−10 keV flux range from 20 to 310 mCrab. Dense monitoring with observations carried out about every second day and a total exposure time of ∼160 ks allowed us to closely track the source evolution over the outburst. Changes in the spectral shape and pulse profiles showed a stable luminosity dependence during the rise and decline. The same type of dependence has been seen in past outbursts. The pulse profile is characterized by several distinct peaks and dips. The profiles show a clear dependence on luminosity with a stark transition at a luminosity of ∼2 × 1036 erg s−1, indicating a change in the emission pattern. Using relativistic raytracing, we demonstrate how anisotropic beaming of emission from an accretion channel with a constant geometrical configuration can give rise to the observed pulse profiles over a range of luminosities.
{"title":"The giant outburst of EXO 2030+375","authors":"P. Thalhammer, R. Ballhausen, E. Sokolova-Lapa, J. Stierhof, A. Zainab, R. Staubert, K. Pottschmidt, J. B. Coley, R. E. Rothschild, G. K. Jaisawal, B. West, P. A. Becker, P. Pradhan, P. Kretschmar, J. Wilms","doi":"10.1051/0004-6361/202348594","DOIUrl":"https://doi.org/10.1051/0004-6361/202348594","url":null,"abstract":"The Be X-ray binary EXO 2030+375 went through its third recorded giant outburst from June 2021 to early 2022. We present the results of both spectral and timing analysis based on NICER monitoring, covering the 2−10 keV flux range from 20 to 310 mCrab. Dense monitoring with observations carried out about every second day and a total exposure time of ∼160 ks allowed us to closely track the source evolution over the outburst. Changes in the spectral shape and pulse profiles showed a stable luminosity dependence during the rise and decline. The same type of dependence has been seen in past outbursts. The pulse profile is characterized by several distinct peaks and dips. The profiles show a clear dependence on luminosity with a stark transition at a luminosity of ∼2 × 10<sup>36<sup/> erg s<sup>−1<sup/>, indicating a change in the emission pattern. Using relativistic raytracing, we demonstrate how anisotropic beaming of emission from an accretion channel with a constant geometrical configuration can give rise to the observed pulse profiles over a range of luminosities.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142042686","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 : 2024-08-22DOI: 10.1051/0004-6361/202451525
M. Agúndez, C. Bermúdez, C. Cabezas, G. Molpeceres, Y. Endo, N. Marcelino, B. Tercero, J.-C. Guillemin, P. de Vicente, J. Cernicharo
While the nitrile group is by far the most prevalent one among interstellar molecules, the existence of interstellar dinitriles (molecules containing two −CN groups) has recently been proven. Here we report the discovery of two new dinitriles in the cold dense cloud TMC-1. These newly identified species are malononitrile, CH2(CN)2, and maleonitrile, the Z isomer of NC−CH=CH−CN, which can be seen as the result of substituting two H atoms with two −CN groups in methane and ethylene, respectively. These two molecules were detected using data from the ongoing QUIJOTE line survey of TMC-1 that is being carried out with the Yebes 40 m telescope. We derive column densities of 1.8 × 1011 cm−2 and 5.1 × 1010 cm−2 for malononitrile and maleonitrile, respectively. This means that they are eight and three times less abundant than HCC−CH2−CN and (E)-HCC−CH=CH−CN, respectively, which are analog molecules detected in TMC-1 in which one −CN group is converted into a −CCH group. This is in line with previous findings in which −CCH derivatives are more abundant than the −CN counterparts in TMC-1. We examined the potential chemical pathways to these two dinitriles, and we find that while maleonitrile can be efficiently formed through the reaction of CN with CH2CHCN, the formation of malononitrile is not clear because the neutral-neutral reactions that could potentially form it are not feasible under the physical conditions of TMC-1.
{"title":"The rich interstellar reservoir of dinitriles: Detection of malononitrile and maleonitrile in TMC-1⋆","authors":"M. Agúndez, C. Bermúdez, C. Cabezas, G. Molpeceres, Y. Endo, N. Marcelino, B. Tercero, J.-C. Guillemin, P. de Vicente, J. Cernicharo","doi":"10.1051/0004-6361/202451525","DOIUrl":"https://doi.org/10.1051/0004-6361/202451525","url":null,"abstract":"While the nitrile group is by far the most prevalent one among interstellar molecules, the existence of interstellar dinitriles (molecules containing two −CN groups) has recently been proven. Here we report the discovery of two new dinitriles in the cold dense cloud TMC-1. These newly identified species are malononitrile, CH<sub>2<sub/>(CN)<sub>2<sub/>, and maleonitrile, the <i>Z<i/> isomer of NC−CH=CH−CN, which can be seen as the result of substituting two H atoms with two −CN groups in methane and ethylene, respectively. These two molecules were detected using data from the ongoing QUIJOTE line survey of TMC-1 that is being carried out with the Yebes 40 m telescope. We derive column densities of 1.8 × 10<sup>11<sup/> cm<sup>−2<sup/> and 5.1 × 10<sup>10<sup/> cm<sup>−2<sup/> for malononitrile and maleonitrile, respectively. This means that they are eight and three times less abundant than HCC−CH<sub>2<sub/>−CN and (<i>E<i/>)-HCC−CH=CH−CN, respectively, which are analog molecules detected in TMC-1 in which one −CN group is converted into a −CCH group. This is in line with previous findings in which −CCH derivatives are more abundant than the −CN counterparts in TMC-1. We examined the potential chemical pathways to these two dinitriles, and we find that while maleonitrile can be efficiently formed through the reaction of CN with CH<sub>2<sub/>CHCN, the formation of malononitrile is not clear because the neutral-neutral reactions that could potentially form it are not feasible under the physical conditions of TMC-1.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142042687","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 : 2024-08-20DOI: 10.1051/0004-6361/202449908
M. Mattern, Ph. André, A. Zavagno, D. Russeil, H. Roussel, N. Peretto, F. Schuller, Y. Shimajiri, J. Di Francesco, D. Arzoumanian, V. Revéret, C. De Breuck
Context. Despite recent progress, the question of what regulates the star formation efficiency (SFE) in galaxies remains one of the most debated problems in astrophysics. According to the dominant picture, star formation (SF) is regulated by turbulence and feedback, and the SFE is ~1–2% or less per local free-fall time on all scales from Galactic clouds to high-redshift galaxies. In an alternate scenario, the star formation rate (SFR) in galactic disks is linearly proportional to the mass of dense gas above some critical density threshold ~104 cm–3.Aims. We aim to discriminate between these two pictures thanks to high-resolution submillimeter and mid-infrared imaging observations, which trace both dense gas and young stellar objects (YSOs) for a comprehensive sample of 49 nearby massive SF complexes out to a distance of d ~ 3 kpc in the Galactic disk.Methods. We used data from CAFFEINE, a complete 350/450 µm survey with APEX/ArTéMiS of the densest portions of all southern molecular clouds at d ≲ 3 kpc, in combination with Herschel data to produce column density maps at a factor of ~4 higher resolution (8") than standard Herschel column density maps (36″). Our maps are free of any saturation effect around luminous high-mass pro-tostellar objects and resolve the structure of dense gas and the typical ~0.1 pc width of molecular filaments out to 3 kpc, which is the most important asset of the present study and is impossible to achieve with Herschel data alone. Coupled with SFR estimates derived from Spitzer mid-infrared observations of the YSO content of the same clouds, this allowed us to study the dependence of the SFE on density in the CAFFEINE clouds. We also combine our findings with existing SF efficiency measurements in nearby clouds to extend our analysis down to lower column densities.Results. Our results suggest that the SFE does not increase with density above the critical threshold and support a scenario in which the SFE in dense gas is approximately constant (independent of free-fall time). However, the SF efficiency measurements traced by Class I YSOs in nearby clouds are more inconclusive, since they are consistent with both the presence of a density threshold and a dependence on density above the threshold. Overall, we suggest that the SF efficiency in dense gas is primarily governed by the physics of filament fragmentation into protostellar cores.
背景。尽管最近取得了一些进展，但星系中恒星形成效率（SFE）的调节因素仍然是天体物理学中争论最多的问题之一。主流观点认为，恒星形成（SF）受湍流和反馈的调节，从银河系云到高红移星系，在所有尺度上，每局部自由落体时间的恒星形成率（SFE）约为1-2%或更低。在另一种情况下，星系盘中的恒星形成率（SFR）与超过某个临界密度阈值~104 cm-3的致密气体质量成线性比例。我们利用高分辨率的亚毫米波和中红外成像观测，对银河系盘中距离 d ~ 3 kpc 的 49 个邻近大质量 SF 复合体样本进行了高密度气体和年轻恒星天体（YSO）的综合跟踪观测，旨在区分这两种情况。CAFFEINE是利用APEX/ArTéMiS对d ≲ 3 kpc处所有南方分子云最稠密的部分进行的一次完整的350/450 µm巡天，我们利用CAFFEINE的数据，结合Herschel的数据绘制了柱密度图，其分辨率（8"）比标准的Herschel柱密度图（36″）高出约4倍。我们的地图在高亮度高质原恒星天体周围不存在任何饱和效应，并能解析稠密气体的结构和典型的 ~0.1 pc 宽度的分子细丝，最远可达 3 kpc，这是本研究最重要的资产，也是仅靠赫歇耳数据无法实现的。结合斯皮策（Spitzer）中红外观测对同一云中的 YSO 含量得出的 SFR 估计值，我们可以研究 CAFFEINE 云中的 SFE 与密度的关系。我们还将我们的发现与附近云层中现有的SF效率测量结果相结合，将我们的分析扩展到更低的柱密度。我们的结果表明，在临界阈值以上，SFE并不随密度的增加而增加，并支持稠密气体中的SFE近似恒定（与自由落体时间无关）的设想。然而，I类YSO在附近云层中追踪到的SF效率测量结果却并不确定，因为它们既符合密度临界值的存在，也符合临界值以上密度的依赖性。总之，我们认为稠密气体中的SF效率主要受长丝碎裂成原恒星核心的物理过程的制约。
{"title":"Understanding the star formation efficiency in dense gas: Initial results from the CAFFEINE survey with ArTéMiS★","authors":"M. Mattern, Ph. André, A. Zavagno, D. Russeil, H. Roussel, N. Peretto, F. Schuller, Y. Shimajiri, J. Di Francesco, D. Arzoumanian, V. Revéret, C. De Breuck","doi":"10.1051/0004-6361/202449908","DOIUrl":"https://doi.org/10.1051/0004-6361/202449908","url":null,"abstract":"<i>Context.<i/> Despite recent progress, the question of what regulates the star formation efficiency (SFE) in galaxies remains one of the most debated problems in astrophysics. According to the dominant picture, star formation (SF) is regulated by turbulence and feedback, and the SFE is ~1–2% or less per local free-fall time on all scales from Galactic clouds to high-redshift galaxies. In an alternate scenario, the star formation rate (SFR) in galactic disks is linearly proportional to the mass of dense gas above some critical density threshold ~10<sup>4<sup/> cm<sup>–3<sup/>.<i>Aims.<i/> We aim to discriminate between these two pictures thanks to high-resolution submillimeter and mid-infrared imaging observations, which trace both dense gas and young stellar objects (YSOs) for a comprehensive sample of 49 nearby massive SF complexes out to a distance of <i>d ~<i/> 3 kpc in the Galactic disk.<i>Methods.<i/> We used data from CAFFEINE, a complete 350/450 µm survey with APEX/ArTéMiS of the densest portions of all southern molecular clouds at <i>d<i/> ≲ 3 kpc, in combination with <i>Herschel<i/> data to produce column density maps at a factor of ~4 higher resolution (8\") than standard <i>Herschel<i/> column density maps (36″). Our maps are free of any saturation effect around luminous high-mass pro-tostellar objects and resolve the structure of dense gas and the typical ~0.1 pc width of molecular filaments out to 3 kpc, which is the most important asset of the present study and is impossible to achieve with <i>Herschel<i/> data alone. Coupled with SFR estimates derived from <i>Spitzer<i/> mid-infrared observations of the YSO content of the same clouds, this allowed us to study the dependence of the SFE on density in the CAFFEINE clouds. We also combine our findings with existing SF efficiency measurements in nearby clouds to extend our analysis down to lower column densities.<i>Results.<i/> Our results suggest that the SFE does not increase with density above the critical threshold and support a scenario in which the SFE in dense gas is approximately constant (independent of free-fall time). However, the SF efficiency measurements traced by Class I YSOs in nearby clouds are more inconclusive, since they are consistent with both the presence of a density threshold and a dependence on density above the threshold. Overall, we suggest that the SF efficiency in dense gas is primarily governed by the physics of filament fragmentation into protostellar cores.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142013796","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 : 2024-08-15DOI: 10.1051/0004-6361/202451319
R. Fuentetaja, C. Cabezas, Y. Endo, M. Agúndez, B. Tercero, N. Marcelino, P. de Vicente, J. Cernicharo
We report the discovery of HNC5 in TMC-1. Six lines have been found in harmonic relation, with quantum numbers J = 12−11 up to J = 17−16. The lines can be reproduced with the standard frequency relation for linear molecules with B = 1361.75034 ± 0.00033 MHz and D = 32.2 ± 0.7 Hz. The assignment of the carrier to iminopentadienylidene was achieved through examining the possible candidates at a high level of theoretical ab initio calculations. Motivated by the good agreement between the observed B and the calculated value for HNC5, we searched for it in the laboratory and observed the transitions J = 5−4 to 7−6. The derived rotational and distortion constants are 1361.74998 ± 0.00040 MHz and 26.5 ± 5.5 Hz, respectively. Hence, we solidly conclude that the carrier of the lines found in TMC-1 is HNC5. The calculated dipole moment for this species is 7.7 D and the derived column density is (1.3 ± 0.2) × 1010 cm−2. We used the new QUIJOTE data to improve previous observations of HC4NC and found that the abundance ratio HC4NC/HNC5 is 10 ± 2. The abundance ratio of HC5N and its two isomers HC4NC and HNC5 is 500 ± 80 and 5100 ± 800, respectively. These abundance ratios are higher by a factor of ∼10 than those of the equivalent isomers of HC3N. Chemical models reproduce the observed abundances reasonably well when a chemistry similar to that of the smaller species C3HN isomers is adopted. The formation of HNC5 and HC4NC arises from the dissociative recombination with electrons of the cations HC5NH+ and HC4NCH+.
{"title":"Space and laboratory discovery of iminopentadienylidene, HNC5⋆","authors":"R. Fuentetaja, C. Cabezas, Y. Endo, M. Agúndez, B. Tercero, N. Marcelino, P. de Vicente, J. Cernicharo","doi":"10.1051/0004-6361/202451319","DOIUrl":"https://doi.org/10.1051/0004-6361/202451319","url":null,"abstract":"We report the discovery of HNC<sub>5<sub/> in TMC-1. Six lines have been found in harmonic relation, with quantum numbers <i>J<i/> = 12−11 up to <i>J<i/> = 17−16. The lines can be reproduced with the standard frequency relation for linear molecules with <i>B<i/> = 1361.75034 ± 0.00033 MHz and <i>D<i/> = 32.2 ± 0.7 Hz. The assignment of the carrier to iminopentadienylidene was achieved through examining the possible candidates at a high level of theoretical ab initio calculations. Motivated by the good agreement between the observed <i>B<i/> and the calculated value for HNC<sub>5<sub/>, we searched for it in the laboratory and observed the transitions <i>J<i/> = 5−4 to 7−6. The derived rotational and distortion constants are 1361.74998 ± 0.00040 MHz and 26.5 ± 5.5 Hz, respectively. Hence, we solidly conclude that the carrier of the lines found in TMC-1 is HNC<sub>5<sub/>. The calculated dipole moment for this species is 7.7 D and the derived column density is (1.3 ± 0.2) × 10<sup>10<sup/> cm<sup>−2<sup/>. We used the new QUIJOTE data to improve previous observations of HC<sub>4<sub/>NC and found that the abundance ratio HC<sub>4<sub/>NC/HNC<sub>5<sub/> is 10 ± 2. The abundance ratio of HC<sub>5<sub/>N and its two isomers HC<sub>4<sub/>NC and HNC<sub>5<sub/> is 500 ± 80 and 5100 ± 800, respectively. These abundance ratios are higher by a factor of ∼10 than those of the equivalent isomers of HC<sub>3<sub/>N. Chemical models reproduce the observed abundances reasonably well when a chemistry similar to that of the smaller species C<sub>3<sub/>HN isomers is adopted. The formation of HNC<sub>5<sub/> and HC<sub>4<sub/>NC arises from the dissociative recombination with electrons of the cations HC<sub>5<sub/>NH<sup>+<sup/> and HC<sub>4<sub/>NCH<sup>+<sup/>.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141992008","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 : 2024-08-15DOI: 10.1051/0004-6361/202450608
Thallis Pessi, Régis Cartier, Emilio Hueichapan, Danielle de Brito Silva, Jose L. Prieto, Ricardo R. Muñoz, Gustavo E. Medina, Paula Diaz, Ting S. Li
Context. We present an analysis of very early high-resolution spectroscopic observations of the Type II supernova (SN) 2024ggi, a nearby SN that occurred in the galaxy NGC 3621 at a distance of 7.24 Mpc (z ≈ 0.002435). These observations represent the earliest high-resolution spectra of a Type II SN ever made.Aims. We analyzed the very early-phase spectroscopic evolution of SN 2024ggi obtained in a short interval at 20.6 and 27.8 h after its discovery, or 26.6 and 33.8 h after the SN first light. Observations were obtained with the high-resolution spectrograph MIKE (R ≈ 22 600 − 28 000) at the 6.5 m Magellan Clay Telescope, located at the Las Campanas Observatory, on the night of April 12, 2024 UT.Methods. The emission lines were identified and studied in detail during the first hours of SN 2024ggi. We analyzed the evolution of ions of H I, He I, He II, N III, C III, Si IV, N IV, and C IV detected across the spectra. We modeled these features with multiple Gaussian and Lorentzian profiles, and estimated their velocities and full widths at half maximum (FWHMs).Results. The spectra show asymmetric emission lines of H I, He II, C IV, and N IV that can be described by narrow Gaussian cores (FWHM ≤ 200 km s−1) with broader Lorentzian wings, and symmetric narrow emission lines of He I, N III, and C III. The emission lines of He I are detected only in the first spectrum, indicating the rapid ionization of He I to He II. The narrow components of the emission lines show a systematic blueshift relative to their zero-velocity position, with an increase of ∼18 km s−1 in the average velocity between the two epochs. The broad Lorentzian components show a blueshift in velocity relative to the narrow components, and a significant increase in the average velocity of ∼103 km s−1. Such a rapid evolution and significant ionization changes in a short period of time were never observed before, and are probably a consequence of the radiative acceleration generated in the SN explosion.
背景我们对 2024ggi 这颗发生在距离 7.24 Mpc（z ≈ 0.002435）的 NGC 3621 星系附近的 II 型超新星（SN）的早期高分辨率光谱观测结果进行了分析。这些观测数据是迄今为止获得的最早的II型SN高分辨率光谱。我们分析了SN 2024ggi在被发现后20.6和27.8小时，或SN首次点亮后26.6和33.8小时的极早期阶段的光谱演变。观测是在美国东部时间 2024 年 4 月 12 日晚，利用位于拉斯坎帕纳斯天文台的 6.5 米麦哲伦粘土望远镜的高分辨率光谱仪 MIKE（R ≈ 22 600 - 28 000）进行的。在 SN 2024ggi 发生的最初几个小时里，我们对发射线进行了详细的识别和研究。我们分析了光谱中检测到的 H I、He I、He II、N III、C III、Si IV、N IV 和 C IV 离子的演变。我们用多个高斯和洛伦兹剖面对这些特征进行了建模，并估算了它们的速度和半最大全宽（FWHM）。光谱显示了 H I、He II、C IV 和 N IV 的非对称发射线，这些发射线可以用带较宽洛伦兹翼的窄高斯核心（全宽≤ 200 km s-1）来描述；还显示了 He I、N III 和 C III 的对称窄发射线。He I 的发射线仅在第一条光谱中被探测到，表明 He I 被快速电离为 He II。发射线的窄分量显示出相对于其零速度位置的系统蓝移，两个纪元之间的平均速度增加了∼18 km s-1。相对于窄分量，宽洛伦兹分量的速度出现了蓝移，平均速度显著增加了 ∼103 km s-1。在短时间内发生如此快速的演化和显著的电离变化是以前从未观测到的，这可能是SN爆炸产生的辐射加速的结果。
{"title":"Early emission lines in SN 2024ggi revealed by high-resolution spectroscopy","authors":"Thallis Pessi, Régis Cartier, Emilio Hueichapan, Danielle de Brito Silva, Jose L. Prieto, Ricardo R. Muñoz, Gustavo E. Medina, Paula Diaz, Ting S. Li","doi":"10.1051/0004-6361/202450608","DOIUrl":"https://doi.org/10.1051/0004-6361/202450608","url":null,"abstract":"<i>Context.<i/> We present an analysis of very early high-resolution spectroscopic observations of the Type II supernova (SN) 2024ggi, a nearby SN that occurred in the galaxy NGC 3621 at a distance of 7.24 Mpc (<i>z<i/> ≈ 0.002435). These observations represent the earliest high-resolution spectra of a Type II SN ever made.<i>Aims.<i/> We analyzed the very early-phase spectroscopic evolution of SN 2024ggi obtained in a short interval at 20.6 and 27.8 h after its discovery, or 26.6 and 33.8 h after the SN first light. Observations were obtained with the high-resolution spectrograph MIKE (<i>R<i/> ≈ 22 600 − 28 000) at the 6.5 m <i>Magellan Clay<i/> Telescope, located at the Las Campanas Observatory, on the night of April 12, 2024 UT.<i>Methods.<i/> The emission lines were identified and studied in detail during the first hours of SN 2024ggi. We analyzed the evolution of ions of H I, He I, He II, N III, C III, Si IV, N IV, and C IV detected across the spectra. We modeled these features with multiple Gaussian and Lorentzian profiles, and estimated their velocities and full widths at half maximum (FWHMs).<i>Results.<i/> The spectra show asymmetric emission lines of H I, He II, C IV, and N IV that can be described by narrow Gaussian cores (FWHM ≤ 200 km s<sup>−1<sup/>) with broader Lorentzian wings, and symmetric narrow emission lines of He I, N III, and C III. The emission lines of He I are detected only in the first spectrum, indicating the rapid ionization of He I to He II. The narrow components of the emission lines show a systematic blueshift relative to their zero-velocity position, with an increase of ∼18 km s<sup>−1<sup/> in the average velocity between the two epochs. The broad Lorentzian components show a blueshift in velocity relative to the narrow components, and a significant increase in the average velocity of ∼103 km s<sup>−1<sup/>. Such a rapid evolution and significant ionization changes in a short period of time were never observed before, and are probably a consequence of the radiative acceleration generated in the SN explosion.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141992017","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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