Astronomy & Astrophysics最新文献

{"title":"Size and kinematics of the low-ionization broad emission line region from microlensing-induced line profile distortions in gravitationally lensed quasars","authors":"Damien Hutsemékers, Dominique Sluse, Đorđe Savić","doi":"10.1051/0004-6361/202452240","DOIUrl":"https://doi.org/10.1051/0004-6361/202452240","url":null,"abstract":"Microlensing-induced distortions of broad emission line profiles observed in the spectra of gravitationally lensed quasars can be used to probe the size, geometry, and kinematics of the broad-line region (BLR). To this end, single-epoch Mg II or H<i>α<i/> line profile distortions observed in five gravitationally lensed quasars, J1131-1231, J1226-0006, J1355-2257, J1339+1310, and HE0435-1223, have been compared with simulated ones. The simulations are based on three BLR models, a Keplerian disk (KD), an equatorial wind (EW), and a polar wind (PW), with different sizes, inclinations, and emissivities. The models that best reproduce the observed line profile distortions were identified using a Bayesian probabilistic approach. We find that the wide variety of observed line profile distortions can be reproduced with microlensing-induced distortions of line profiles generated by our BLR models. For J1131, J1226, and HE0435, the most likely model for the Mg II and H<i>α<i/> BLRs is either KD or EW, depending on the orientation of the magnification map with respect to the BLR axis. This shows that the line profile distortions depend on the position and orientation of the isovelocity parts of the BLR with respect to the caustic network, and not only on their different effective sizes. For the Mg II BLRs in J1355 and J1339, the EW model is preferred. For all objects, the PW model has a lower probability. As for the high-ionization C IV BLR, we conclude that disk geometries with kinematics dominated by either Keplerian rotation or equatorial outflow best reproduce the microlensing effects on the low-ionization Mg II and H<i>α<i/> emission line profiles. The half-light radii of the Mg II and H<i>α<i/> BLRs are measured in the range of 3 to 25 light-days. We also confirm that the size of the region emitting the low-ionization lines is larger than the region emitting the high-ionization lines, with a factor of four measured between the sizes of the Mg II and C IV emitting regions in J1339. Unexpectedly, the microlensing BLR radii of the Mg II and H<i>α<i/> BLRs are found to be systematically below the radius-luminosity (<i>R<i/> − <i>L<i/>) relations derived from reverberation mapping, confirming that the intrinsic dispersion of the BLR radii with respect to the <i>R<i/> − <i>L<i/> relations is large, but also revealing a selection bias that affects microlensing-based BLR size measurements. This bias arises from the fact that, if microlensing-induced line profile distortions are observed in a lensed quasar, the BLR radius should be comparable to the microlensing Einstein radius, which varies only weakly with typical lens and source redshifts.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678567","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}

{"title":"Hints of auroral and magnetospheric polarized radio emission from the scallop-shell star 2MASS J05082729–2101444","authors":"Simranpreet Kaur, Daniele Viganò, Víctor J. S. Béjar, Álvaro Sánchez Monge, Òscar Morata, Devojyoti Kansabanik, Josep Miquel Girart, Juan Carlos Morales, Guillem Anglada-Escudé, Felipe Murgas, Yutong Shan, Ekaterina Ilin, Miguel Pérez-Torres, María Rosa Zapatero Osorio, Pedro J. Amado, José A. Caballero, Fabio Del Sordo, Enric Palle, Andreas Quirrenbach, Ansgar Reiners, Ignasi Ribas","doi":"10.1051/0004-6361/202452037","DOIUrl":"https://doi.org/10.1051/0004-6361/202452037","url":null,"abstract":"Scallop-shell stars, a recently discovered class of young M dwarfs, show complex optical light curves that are characterized by periodic dips as well as other features that are stable over tens to hundreds of rotation cycles. The origin of these features is not well-understood. 2MASS J05082729−2101444 is a ∼25 Myr old scallop-shell star that was identified using TESS data; it has a photometric period of 6.73 h that has been attributed to rotation. Of the ∼50 recently confirmed scallop-shell stars, it is one of the few detected at radio frequencies between 1 and 8 GHz. We observed this rare system with the upgraded Giant Meterwave Radio Telescope at 575–720 MHz, covering 88% of the photometric period in each of the two observations scheduled almost a month apart in 2023. We detected approximately millijansky emission from the target in both epochs, with a significant circular polarization fraction: |<i>V<i/>/<i>I<i/>|∼20 − 50%. The 3.5-minute phase-folded light curves show unique variability in circular polarization. We detected an approximately hour-long helicity reversal during both epochs, and the reversals had similar amplitudes, lengths, and (possibly) occured at similar phases. These results suggest two emission components: The first is a persistent, moderately polarized component possibly ascribable to gyro-synchrotron emission driven by centrifugal breakout events. The second is a highly polarized, short burst-like component that is likely due to an electron cyclotron maser (ECM); it is indicative of auroral emission and is potentially responsible for the helicity reversal. To explain this, we discuss the different origins of the plasma responsible for the radio emission, including the possibility that the occulting material is acting as a plasma source. Future coordinated multifrequency radio and optical observations can further constrain the underlying scenario, as well as the magnetic geometry of the system, if we assume an ECM-like auroral emission.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678536","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}

{"title":"Infrared spectra of solid-state ethanolamine: Laboratory data in support of JWST observations","authors":"T. Suhasaria, S. M. Wee, R. Basalgète, S. A. Krasnokutski, C. Jäger, G. Perotti, Th. Henning","doi":"10.1051/0004-6361/202450097","DOIUrl":"https://doi.org/10.1051/0004-6361/202450097","url":null,"abstract":"<i>Context.<i/> Ethanolamine (NH<sub>2<sub/>CH<sub>2<sub/>CH<sub>2<sub/>OH; EA) has been identified in the gas phase of the interstellar medium within molecular clouds. Although EA has not been directly observed in the molecular ice phase, a solid-state formation mechanism has been proposed. However, the current literature lacks an estimation of the infrared band strengths of EA ices, which are crucial data for quantifying potential astronomical observations and laboratory findings related to their formation or destruction via energetic processing.<i>Aims.<i/> We conducted an experimental investigation of solid EA ice at low temperatures to ascertain its infrared band strengths, phase transition temperature, and multilayer binding energy. Since the refractive index and the density of EA ice are unknown, the commonly used laser interferometry method was not applied. Infrared band strengths were determined using three distinct methods. In addition to evaluating EA band strengths, we also tested the advantages and disadvantages of different approaches used for this purpose. The obtained lab spectrum of EA was compared with the publicly available MIRI MRS James Webb Space Telescope observations towards a low-mass protostar.<i>Methods.<i/> We used a combination of Fourier-transform transmission infrared spectroscopy and quadrupole mass spectrometry.<i>Results.<i/> The phase transition temperature for EA ice falls within the range of 175 to 185 K. Among the discussed methods, the simple pressure gauge method provides a reasonable estimate of band strength. We derived a band strength value of about 1 × 10<sup>−17<sup/> cm molecule<sup>−1<sup/> for the NH<sub>2<sub/> bending mode in the EA molecules. Additionally, temperature-programmed desorption analysis yielded a multilayer desorption energy of 0.61±0.01 eV. By comparing the laboratory data documented in this study with the JWST spectrum of the low-mass protostar IRAS 2A, an upper-limit for the EA ice abundances was derived.<i>Conclusions.<i/> This study addresses the lack of quantitative infrared measurements of EA at low temperatures, crucial for understanding EA’s astronomical and laboratory presence and formation routes. Our approach presents a simple yet effective method for determining the infrared band strengths of molecules with a reasonable level of accuracy.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"197 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678630","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}

{"title":"Multi-epoch jet outbursts in Abell 496: Synchrotron ageing and buoyant X-ray cavities draped by warm gas filaments","authors":"F. Ubertosi, S. Giacintucci, T. Clarke, M. Markevitch, T. Venturi, E. O’Sullivan, M. Gitti","doi":"10.1051/0004-6361/202451766","DOIUrl":"https://doi.org/10.1051/0004-6361/202451766","url":null,"abstract":"<i>Aims.<i/> The galaxy cluster Abell 496 has been extensively studied in the past for the clear sloshing motion of its hot intracluster medium (ICM) on large scales, but the interplay between the central radio galaxy and the surrounding cluster atmosphere is mostly unexplored. We present a dedicated radio, X-ray, and optical study of Abell 496 with the aim being to investigate this connection.<i>Methods.<i/> We use deep radio images obtained with the Giant Metrewave Radio Telescope (GMRT) at 150, 330, and 617 MHz, the Very Large Array (VLA) at 1.4 and 4.8 GHz, and the VLA Low Band Ionosphere and Transient Experiment (VLITE) at 340 MHz, with angular resolutions ranging from 0.​″5 to 25″. Additionally, we use archival <i>Chandra<i/> and Very Large Telescope (VLT) MUSE observations.<i>Results.<i/> The radio images reveal three distinct periods of jet activity: an ongoing episode on subkiloparsec scales with an inverted radio spectrum; an older episode that produced lobes on scales of ∼20 kpc, which now have a steep spectral index (<i>α<i/> = 2.0 ± 0.1); and an even older episode that produced lobes on scales of ∼50 − 100 kpc with an ultrasteep spectrum (<i>α<i/> = 2.7 ± 0.2). Archival <i>Chandra<i/> X-ray observations show that the older and oldest episodes excavated two generations of cavities in the hot gas of the cluster. The outermost X-ray cavity has a clear mushroom-head shape, likely caused by its buoyant rise in the cluster’s potential. Cooling of the hot gas is ongoing in the innermost 20 kpc, where warm, H<i>α<i/>-bright filaments are visible in VLT-MUSE data. The H<i>α<i/>-filaments are stretched toward the mushroom-head cavity, which may have stimulated ICM cooling in its wake. We conclude by discussing our nondetection of a radio mini-halo in this vigorously sloshing but low-mass galaxy cluster.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"231 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679144","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}

{"title":"A survey of extremely metal-poor gas at cosmic noon","authors":"Louise Welsh, Ryan Cooke, Michele Fumagalli, Max Pettini, Gwen C. Rudie","doi":"10.1051/0004-6361/202451147","DOIUrl":"https://doi.org/10.1051/0004-6361/202451147","url":null,"abstract":"<i>Aims.<i/> We aim to study the high-precision chemical abundances of metal-poor gas clouds at cosmic noon (2 < <i>z<i/> < 4) and investigate the associated enrichment histories.<i>Methods.<i/> We analyze the abundances of four newly discovered metal-poor gas clouds utilizing observations conducted with Keck/HIRES and VLT/UVES. These systems are classified as very metal-poor (VMP), with [Fe/H] < −2.57, and one system qualifies as an extremely metal-poor (EMP) Damped Lyman-<i>α<i/> (DLA) system with [Fe/H] = −3.13 ± 0.06. In combination with new high-resolution data of two previously known EMP DLAs and 2 systems reported in the literature, we conduct a comprehensive analysis of eight of the most metal-poor gas clouds currently known. We focus on high-precision abundance measurements using the elements: C, N, O, Al, Si, and Fe.<i>Results.<i/> Our findings indicate increasing evidence of elevated [O/Fe] abundances when [Fe/H] < −3. EMP DLAs are well-modeled with a mean value of [O/Fe]<sub>cen<sub/> = +0.50 ± 0.04 and an intrinsic scatter of σ<sub>int[O/Fe]<sub/> = 0.13<sub>-0.04<sub/><sup>+0.06<sup/>. While VMP DLAs are well-modeled with [O/Fe]<sub>cen<sub/> = +0.40 ± 0.02 and <i>σ<i/><sub>int, [O/Fe]<sub/> = 0.06 ± 0.02. We further find tentative evidence of a redshift evolution of [C/O] across these most metal-poor DLAs with lower redshift systems showing elevated [C/O] ratios. Using the measured abundances, combined with a stochastic chemical enrichment model, we investigate the properties of the stellar population responsible for enriching EMP gas at cosmic noon. We find that the chemistry of these systems is best explained via the enrichment of just two massive progenitors, <i>N<i/><sub>⋆<sub/> = 2 ± 1, that ended their lives as core collapse SNe with a typical explosion energy <i>E<i/><sub>exp<sub/> = (1.6 ± 0.6)×10<sup>51<sup/> erg. These progenitors formed obeying a Salpeter-like power-law IMF, where all stars of mass greater than <i>M<i/><sub>max<sub/> = 32<sub>-4<sub/><sup>+10<sup/>M<sub>⊙<sub/> collapse directly to black holes and do not contribute to the metal enrichment.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"191 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678535","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}

{"title":"Connecting integrated red giant branch mass loss from asteroseismology and globular clusters","authors":"K. Brogaard, A. Miglio, W. E. van Rossem, E. Willett, J. S. Thomsen","doi":"10.1051/0004-6361/202452033","DOIUrl":"https://doi.org/10.1051/0004-6361/202452033","url":null,"abstract":"<i>Context.<i/> Asteroseismic investigations of solar-like oscillations in giant stars enable the derivation of their masses and radii. For mono-age mono-metallicity populations of stars, this allows the integrated red giant branch (RGB) mass loss to be estimated by comparing the median mass of the low-luminosity RGB stars to that of the helium-core-burning (HeCB) stars.<i>Aims.<i/> We aim to exploit quasi-mono-age mono-metallicity populations of field stars in the <i>α<i/>-rich sequence of the Milky Way (MW) to derive the integrated mass loss and its dependence on metallicity. By comparison to metal-rich globular clusters (GCs), we wish to determine whether the RGB mass loss differs in the two environments.<i>Methods.<i/> We used catalogues of asteroseismic parameters based on time-series photometry from the <i>Kepler<i/> and K2 missions cross-matched to spectroscopic information from APOGEE-DR17, photometry from 2MASS, parallaxes from Gaia DR3, and reddening maps. We determined the RGB mass loss by comparing mass distributions of RGB and HeCB stars in three metallicity bins. For two GCs, the mass loss is derived from colour–magnitude diagrams.<i>Results.<i/> We find the integrated RGB mass loss to increase with decreasing metallicity and/or mass in the [Fe/H] range from −0.9 to +0.0. At [Fe/H] = −0.50, the RGB mass loss of MW <i>α<i/>-rich field stars is compatible with that in GCs of the same metallicity.<i>Conclusions.<i/> We provide novel empirical determinations of the integrated mass loss connecting field stars and GC stars at comparable metallicities. These show that mass loss cannot be accurately described by a Reimers mass-loss law with a single value of <i>η<i/>. This should encourage further development of the theory underlying processes involved in mass loss.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678537","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}

{"title":"JADES: Balmer decrement measurements at redshifts 4 < z < 7","authors":"Lester Sandles, Francesco D’Eugenio, Roberto Maiolino, Tobias J. Looser, Santiago Arribas, William M. Baker, Nina Bonaventura, Andrew J. Bunker, Alex J. Cameron, Stefano Carniani, Stephane Charlot, Jacopo Chevallard, Mirko Curti, Emma Curtis-Lake, Anna de Graaff, Daniel J. Eisenstein, Kevin Hainline, Zhiyuan Ji, Benjamin D. Johnson, Gareth C. Jones, Nimisha Kumari, Erica Nelson, Michele Perna, Tim Rawle, Hans-Walter Rix, Brant Robertson, Bruno Rodríguez Del Pino, Jan Scholtz, Irene Shivaei, Renske Smit, Fengwu Sun, Sandro Tacchella, Hannah Übler, Christina C. Williams, Chris Willott, Joris Witstok","doi":"10.1051/0004-6361/202347119","DOIUrl":"https://doi.org/10.1051/0004-6361/202347119","url":null,"abstract":"We present Balmer decrement, H<i>α<i/>/H<i>β<i/>, measurements for a sample of 51 galaxies at redshifts <i>z<i/> = 4 − 7 observed with the JWST/NIRSpec micro-shutter assembly (MSA), as part of the JWST Advanced Deep Extragalactic Survey (JADES). Leveraging 28-hour long exposures and the efficiency of the prism/clear configuration (but also using information from the medium-resolution gratings), we were able to directly probe the low-mass end of the galaxy population, reaching stellar masses, <i>M<i/><sub>⋆<sub/>, as low as 10<sup>7<sup/> M<sub>⊙<sub/>. We find that the correlation between the Balmer decrement and <i>M<i/><sub>⋆<sub/> is already established at these high redshifts, indicating a rapid buildup of dust in moderately massive galaxies at such early epochs. The lowest-mass galaxies in our sample (<i>M<i/><sub>⋆<sub/> = 1 − 3 × 10<sup>7<sup/> M<sub>⊙<sub/>) display a remarkably low Balmer decrement of 2.88 ± 0.08, consistent with Case B, suggesting very little dust content. However, we warn that such a low observed Balmer decrement may also partly be a consequence of an intrinsically lower H<i>α<i/>/H<i>β<i/> resulting from the extreme conditions of the ionised gas in these primeval and unevolved systems. We further compare the Balmer decrement to continuum-derived star formation rates (SFRs), finding tentative evidence of a correlation, which likely traces the underlying connection between the SFR and the mass of cold gas. However, we note that larger samples are required to distinguish between direct and primary correlations from indirect and secondary dependences at such high redshifts.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"76 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679048","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}

{"title":"Collisional damping in debris discs: Only significant if collision velocities are low","authors":"Marija R. Jankovic, Mark C. Wyatt, Torsten Löhne","doi":"10.1051/0004-6361/202451080","DOIUrl":"https://doi.org/10.1051/0004-6361/202451080","url":null,"abstract":"<i>Context<i/>. Dusty debris discs around main sequence stars are observed to vary widely in terms of their vertical thickness. Their vertical structure may be affected by damping in inelastic collisions. Although kinetic models have often been used to study the collisional evolution of debris discs, these models have not yet been used to study the evolution of their vertical structure.<i>Aims<i/>. We extend an existing implementation of a kinetic model of collisional evolution to include the evolution of orbital inclinations and we use this model to study the effects of collisional damping in pre-stirred discs.<i>Methods<i/>. We evolved the number of particles of different masses, eccentricities, and inclinations using the kinetic model and used Monte Carlo simulations to calculate collision rates between particles in the disc. We considered all relevant collisional outcomes including fragmentation, cratering, and growth.<i>Results<i/>. Collisional damping is inefficient if particles can be destroyed by projectiles that are of much lower mass. If that is the case, catastrophic disruptions shape the distributions of eccentricities and inclinations, and their average values evolve slowly and at the same rate for all particle sizes.<i>Conclusions<i/>. The critical projectile-to-target mass ratio (<i>Y<i/><sub>c<sub/>) and the collisional timescale jointly determine the level of collisional damping in debris discs. If <i>Y<i/><sub>c<sub/> is much smaller than unity, a debris disc retains the inclination distribution that it is born with for much longer than the collisional timescale of the largest bodies in the disc. Such a disc should exhibit a vertical thickness that is independent of wavelength even in the absence of other physical processes. Collisional damping is efficient if <i>Y<i/><sub>c<sub/> is of order unity or larger. For millimetre-sized dust grains and common material strength assumptions, this requires collision velocities of lower than ~40 m s<sup>−1<sup/>. We discuss the implications of our findings for exo-Kuiper belts, discs around white dwarfs, and planetary rings.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"197 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678533","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}

{"title":"High-resolution transmission spectroscopy of the hot-Saturn HD 149026b","authors":"Federico Biassoni, Francesco Borsa, Francesco Haardt, Monica Rainer","doi":"10.1051/0004-6361/202451750","DOIUrl":"https://doi.org/10.1051/0004-6361/202451750","url":null,"abstract":"Advances in modern technology have enabled the characterization of exoplanetary atmospheres, which can be achieved by exploitation of the transmission spectroscopy technique. We performed visible (VIS) and near-infrared (NIR) high-resolution spectroscopic observations of one transit of HD 149026b, a close-in orbit sub-Saturn exoplanet by using the GIARPS configuration at the Telescopio Nazionale <i>Galileo<i/> (TNG). We first analyzed the radial-velocity data, refining the value of the projected spin-orbit obliquity (<i>λ<i/>). We then performed transmission spectroscopy, looking for absorption signals from the planetary atmosphere. We find no evidence for H<i>α<i/>, Na I D2-D1, Mg I, or Li I in the VIS and metastable helium triplet He I(2<sup>3<sup/>S) in the NIR using a line-by-line approach. The non-detection of HeI is also supported by theoretical simulations. With the use of the cross-correlation technique (CCF), we do not detect Ti I, V I, Cr I, Fe I, or VO in the visible, or indeed CH<sub>4<sub/>, CO<sub>2<sub/>, H<sub>2<sub/>O, HCN, NH<sub>3<sub/>, or VO in the NIR. Our non-detection of Ti I in the planetary atmosphere is in contrast with a previous detection. We performed injection-retrieval tests, finding that our dataset is sensitive to our Ti I model. The non-detection supports the Ti I cold-trap theory, which is valid for planets with <i>T<i/><sub>eq<sub/> < 2200 K, such as HD 149026b. Although we do not attribute it directly to the planet, we find a possibly significant Ti I signal that is highly redshifted (≃+20 km s<sup>−1<sup/> ) with respect to the planetary rest frame. Redshifted signals are also found in the Fe I and Cr I maps. While we can exclude an eccentric orbit as the cause of this redshifted Ti I signal, we investigated the possibility of material accretion falling onto the star – which is possibly supported by the presence of strong Li I in the stellar spectrum - but obtained inconclusive results. The analysis of multiple transits datasets could shed more light on this target.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"252 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678568","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}

{"title":"CHANG-ES","authors":"V. Heesen, T. Wiegert, J. Irwin, R. Crocker, A. Kiehn, J.-T. Li, Q. D. Wang, M. Stein, R.-J. Dettmar, M. Soida, R. Henriksen, L. Gajović, Y. Yang, M. Brüggen","doi":"10.1051/0004-6361/202451569","DOIUrl":"https://doi.org/10.1051/0004-6361/202451569","url":null,"abstract":"<i>Context.<i/> Cosmic rays may be dynamically very important in driving large-scale galactic winds. Edge-on galaxies give us an outsider’s view of radio haloes, and of their extra-planar cosmic-ray electrons and magnetic fields.<i>Aims.<i/> We present a new radio continuum imaging study of the nearby edge-on galaxy NGC 4217. We examine the distribution of extra-planar cosmic rays and magnetic fields. We observed it with both the <i>Jansky<i/> Very Large Array (JVLA) in the <i>S<i/> band (2–4 GHz) and the LOw Frequency ARray (LOFAR) at 144 MHz.<i>Methods.<i/> We measured vertical intensity profiles and exponential scale heights. We re-imaged both the JVLA and LOFAR data at matched angular resolution in order to measure radio spectral indices between 144 MHz and 3 GHz. Confusing point-like sources were subtracted prior to imaging. We then fitted intensity profiles with cosmic-ray electron advection models, using an isothermal wind model that is driven by a combination of pressure from the hot gas and cosmic rays.<i>Results.<i/> We discover a large-scale radio halo on the north-western side of the galactic disc. The morphology is reminiscent of a bubble extending up to 20 kpc from the disc. We find spectral ageing in the bubble, which allowed us to measure the advection speeds of the cosmic-ray electrons, which accelerate from 300 to 600 km s<sup>−1<sup/>. Assuming energy equipartition between the cosmic rays and the magnetic field, we estimate the bubble may have been inflated by a modest 10% of the kinetic energy injected by supernovae over its dynamical timescale of 35 Myr. While no active galactic nucleus (AGN) has been detected, such activity in the recent past cannot be ruled out.<i>Conclusions.<i/> Non-thermal bubbles with sizes of tens of kiloparsecs may be a ubiquitous feature of star-forming galaxies, and if so this would demonstrate the influence of feedback. Determining possible contributions by AGN feedback will require deeper observations.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142673923","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}