Astronomy & Astrophysics最新文献

{"title":"Determining the statistical significance of meteorite–asteroid pairs using geocentric parameters","authors":"P. M. Shober","doi":"10.1051/0004-6361/202555857","DOIUrl":"https://doi.org/10.1051/0004-6361/202555857","url":null,"abstract":"<i>Context<i/>. Orbital similarity between precisely observed meteorite falls and near-Earth asteroids (NEAs) has been presented for decades as evidence that some meteorites are coming directly from these asteroids. However, analysis of the statistical significance of these pairings is mixed. Based on osculating orbital elements, there is no evidence of statistically significant clustering; however, some analyses that account for secular perturbations suggest that streams are present.<i>Aims<i/>. We tested the statistical significance of meteorite-dropping fireballs and NEA clustering using the <i>D<sub>N<sub/><i/> similarity function based on four geocentric quantities (<i>U, θ, ϕ<i/>, and <i>λ<i/><sub>⊙<sub/>).<i>Methods<i/>. We calculated the cumulative similarity found between 46 meteorite falls, 535 potential meteorite-dropping fireballs, and 20 516 NEAs maintained by NEODyS-2, along with 34 836 NEAs maintained by NASA/JPL HORIZONS. Statistical significance was estimated either by (1) using a kernel density estimation-based method to estimate the sporadic background distribution and thus draw random samples or (2) applying a uniform random solar longitude (<i>λ<i/><sub>⊙<sub/>). Each comparison to the synthetic sporadic population was repeated to estimate the 3<i>σ<i/> region for which the cumulative similarity distribution is consistent with random association levels.<i>Results<i/>. The observed <i>D<sub>N<sub/><i/> cumulative similarity distribution of 46 instrumentally observed meteorite falls, 535 potential meteoritedropping fireballs, and over 30 k NEA radiants (estimated using six different radiant methods) reveals no statistically significant excess of similarity between the populations consistent with streams.<i>Conclusions<i/>. Based on nearly 600 fireball observations and geocentric impact parameters, we find there is no statistically significant clustering between meteorite falls and NEAs. If some meteorites arrive in streams, they make up less than ~0.1% of all falls. Recent asteroid or meteoroid physical processes could still explain features found in meteorites, but this activity is not producing distinguishable orbital streams or pairs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"110 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145209780","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":"Revisiting G29.862–0.0044: A jet cavity disrupted by an outflow in a likely young stellar object wide binary system","authors":"S. Paron, N. C. Martinez, M. E. Ortega, D. Mast, A. Petriella, L. Supán, C. Fariña","doi":"10.1051/0004-6361/202555716","DOIUrl":"https://doi.org/10.1051/0004-6361/202555716","url":null,"abstract":"<i>Aims<i/>. A few years ago, we investigated the massive young stellar object (MYSO) G29.862–0.0044 (YSO-G29), an intriguing star-forming region at a distance of 6.2 kpc. Although the typical disc-jet scenario was proposed to explain the observations, it remained far from conclusive. We wonder if the puzzling observed near-IR features are produced by only one source or if it is due to confusion generated by an unresolved system of YSOs. Unveiling this issue is important for a better understanding of the star-forming processes.<i>Methods<i/>. We analysed YSO-G29 using new observations in the near-IR from Gemini-NIFS, at the radio continuum (10 GHz) from the Jansky Very Large Array (JVLA) and new continuum (1.3 mm) and molecular line data from the Atacama Large Millimeter Array (ALMA).<i>Results<i/>. The near-IR observations allowed us to detect emission of H<sub>2<sub/> 1−0 S(1) and Br<i>γ<i/> lines in YSO-G29, which are compatible with excitation and ionisation from UV radiation propagating in a highly perturbed ambient. In addition, we also found some evidence of H<sub>2<sub/> excitation by collisions. The ALMA data show the presence of a conspicuous and collimated molecular outflow propagating southwards, while to the north, an extended molecular feature perfectly surrounded by the Ks near-IR emission appears. The continuum emission at 1.3 mm allowed us to better resolve the molecular cores, one of which stands out due to its high temperatures and rich chemical composition. From the JVLA observations, we discovered a compact radio continuum source, a likely compact HII region or an ionised jet of a massive protostar, located at ~0.″7 (~0.02 pc) from the main millimetre core. In this way, we propose a YSO wide binary system.<i>Conclusions<i/>. We can explain the nature of the intriguing near-IR features previously observed: Cone-like structures produced by jets or winds of one of the components of the binary system that cleared out the surroundings were disrupted by a molecular outflow probably from the other component. These results complete the picture of what is happening in YSO-G29 and reveal a phenomenon that should be considered when investigating massive star-forming regions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"124 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145203830","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":"The ALMA-QUARKS survey: Extensive detection of acetamide in multiple high-mass star-forming regions","authors":"Chunguo Duan, Xuefang Xu, Qian Gou, Tie Liu, Laurent Pagani, Fengwei Xu, Ke Wang, Xunchuan Liu, Jun Kang, Mingwei He, Jiaxiang Jiao","doi":"10.1051/0004-6361/202556073","DOIUrl":"https://doi.org/10.1051/0004-6361/202556073","url":null,"abstract":"Acetamide (CH<sub>3<sub/>CONH<sub>2<sub/>), a key interstellar amide and a methyl derivative of formamide (NH<sub>2<sub/>CHO), has rarely been detected, limiting insights into its prebiotic relevance. We present the first systematic survey of acetamide toward 52 hot molecular cores using ALMA Band 6 data. We have detected acetamide in ten cores, markedly expanding the inventory of known emitters. The derived column densities of acetamide range from (2.5 ± 0.9) × 10<sup>14<sup/> to (1.5 ± 0.6) × 10<sup>16<sup/> cm<sup>−2<sup/>, compared to formamide’s (1.1 ± 0.1) × 10<sup>15<sup/> to (6.9 ± 0.4) × 10<sup>16<sup/> cm<sup>−2<sup/>. The nearly constant abundance ratios (~3–9) and strong abundance correlation between the two amides across sources suggest a chemically linked formation pathway, likely on grain surfaces. The presence of peptide-like molecules in these regions implies that complex organic species can survive star formation processes, offering a potential pathway toward prebiotic chemistry. These findings constrain the dominant grain-surface formation routes of acetamide, confirm its broader prevalence in high-mass star-forming regions, and underscore the importance of targeted amide surveys in tracing the chemical evolution toward prebiotic complexity.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"56 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145203551","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":"The X-ray statistical properties of dust-obscured galaxies detected by eROSITA","authors":"Akatoki Noboriguchi, Kohei Ichikawa, Yoshiki Toba, Tom Dwelly, Kohei Inayoshi, Toshihiro Kawaguchi, Teng Liu, Yuichi Terashima, Yoshihiro Ueda, Masayuki Akiyama, Marcella Brusa, Johannes Buchner, Kotaro Kohno, Andrea Merloni, Tohru Nagao, Mara Salvato, Hyewon Suh, Tanya Urrutia","doi":"10.1051/0004-6361/202450190","DOIUrl":"https://doi.org/10.1051/0004-6361/202450190","url":null,"abstract":"<i>Context.<i/> The tight correlation between supermassive black hole (SMBH) and host galaxy masses suggests their coevolution. Dust-obscured galaxies (DOGs) are thought to represent this coevolution phase, with active galactic nuclei (AGNs) buried in dust and gas. Despite hosting rapidly growing SMBHs, the X-ray statistical properties of DOGs remain poorly understood due to their rarity and the lack of wide, uniformly sensitive X-ray surveys.<i>Aims.<i/> We construct a sample of X-ray-detected DOGs in the <i>eROSITA<i/> Final Equatorial Depth Survey (eFEDS) field and examine their X-ray statistical properties.<i>Methods.<i/> To construct the DOGs sample, we combined data from the Subaru/HSC SSP (optical), VIKING (near-infrared), and <i>WISE<i/> (mid-infrared) all-sky surveys. We then cross-matched the sample with <i>eROSITA<i/>-detected sources to select X-ray-detected DOGs.<i>Results.<i/> We report the discovery of 5738 IR-bright DOGs within the 60 deg<sup>2<sup/> area covered by both eFEDS and VIKING, including 65 X-ray-detected DOGs (eFEDS-DOGs). Among these, 41 eFEDS-DOGs exhibit a near- to mid-IR power-law slope, indicating dust-obscured AGNs. Hydrogen column densities (<i>N<i/><sub>H<sub/>) of eFEDS-DOGs span 10<sup>20<sup/> < <i>N<i/><sub>H<sub/>/cm<sup>−2<sup/> ≲ 10<sup>23<sup/>, including even unobscured AGNs. Most IR-bright DOGs remain undetected in X-rays, implying heavy obscuration (<i>N<i/><sub>H<sub/>/cm<sup>−2<sup/> > 10<sup>23<sup/>). eFEDS-DOGs, identified via the wide-area <i>eROSITA<i/> survey, represent a less obscured DOG phase, possibly tracing the decline of dust/gas obscuration due to AGN feedback such as gas stripping or outflows. Some eFEDS-DOGs deviate up to ∼1 dex below the <i>L<i/><sub>6 μm<sub/>–<i>L<i/><sub>0.5 − 2 keV<sub/><sup>(abs, corr)<sup/> relation, potentially indicating high Eddington ratios near the Eddington limit. This suggests that eFEDS-DOGs are promising candidates for rapidly growing black holes in an early AGN feedback phase.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145203504","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":"Analysis of the isotopologues of CS, CCS, CCCS, HCS+, HCCS+, and H2CS in TMC-1 with the QUIJOTE line survey★","authors":"R. Fuentetaja, C. Cabezas, Y. Endo, M. Agúndez, A. Godard Palluet, F. Lique, B. Tercero, N. Marcelino, P. de Vicente, J. Cernicharo","doi":"10.1051/0004-6361/202554035","DOIUrl":"https://doi.org/10.1051/0004-6361/202554035","url":null,"abstract":"We performed a detailed analysis of the isotopologues with <sup>13<sup/>C, <sup>34<sup/>S, <sup>33<sup/>S, and <sup>36<sup/>S of the sulphur-bearing molecules CS, CCS, CCCS, HCS<sup>+<sup/>, HCCS<sup>+<sup/>, and H<sub>2<sub/>CS towards the starless core TMC-1 using the QUIJOTE<sup>1<sup/> line survey. The observations were obtained with the Yebes 40 m radio telescope, and the sensitivity of the data varied between 0.08 and 0.2 mK in the 31–50 GHz range. Observations with the IRAM 30 m radio telescope of the most abundant isotopologues of these species are also presented and used to estimate volume densities and to constrain the excitation conditions of these molecules. Among these species, we report the first detection in space of C<sup>13<sup/>C<sup>34<sup/>S, CC<sup>33<sup/>S, CCC<sup>33<sup/>S, HC<sup>33<sup/>S<sup>+<sup/>, and HCC<sup>34<sup/>S<sup>+<sup/>. C<sup>36<sup/>S is also detected for the first time in a cold starless object. These data were complemented with sensitive maps that provide the spatial distribution of most of these species. Using the available collisional rate coefficients for each species, we modeled the observed line intensities using the large velocity gradient method for the radiative transfer. The results allowed us to report the most complete analysis of the column densities of the C<sub><i>n<i/><sub/>S family and to compare the abundance ratios of all detected isotopologues. Adopting a kinetic temperature for TMC-1 of 9 K, we found that n(H<sub>2<sub/>)=0.9–1.5×10<sup>4<sup/> cm<sup>−3<sup/> can explain the observed decline in intensity with increasing rotational levels <i>J<i/> for all observed molecules. We derived the rotational constants for the C<sup>13<sup/>C<sup>34<sup/>S, CC<sup>33<sup/>S, CCC<sup>33<sup/>S, HC<sup>33<sup/>S<sup>+<sup/>, and HCC<sup>34<sup/>S<sup>+<sup/> isotopologues from new laboratory data and complemented them with the frequencies of the observed lines. We find that all sulphur isotopologues are consistent with solar isotopic abundance ratios. Accurate <sup>12<sup/>C/<sup>13<sup/>C abundances were derived and, as previously suggested, the <sup>13<sup/>C isotopologues of CCS and CCCS show strong abundance anomalies depending on the position of the substituted carbon. Nevertheless, the <sup>12<sup/>C/<sup>13<sup/>C abundance ratio is practically identical to the solar value for CS, HCS<sup>+<sup/>, and H<sub>2<sub/>CS. We also searched for the isotopologues of other S-bearing molecules in the 31–50 GHz domain (HCS, HSC, NCS, H<sub>2<sub/>CCS, HCSCN, HCCCS<sup>+<sup/>, C<sub>4<sub/>S, and C<sub>5<sub/>S). The expected intensities for their <sup>34<sup/>S and <sup>13<sup/>C isotopologues are too low to be detected with the present sensitivity of the QUIJOTE line survey, however. The results presented in this work provide new insights into the molecular composition, isotopic abundances, and physical conditions of the cold starless core TMC-1.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188719","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":"Gamma radiation from cosmic rays escaping a young supernova remnant: The case of Cas A","authors":"Pasquale Blasi","doi":"10.1051/0004-6361/202555995","DOIUrl":"https://doi.org/10.1051/0004-6361/202555995","url":null,"abstract":"The escape of accelerated particles from supernova remnants remains one of the central and yet least understood aspects of the origin of cosmic rays. Here we use the results of the recent LHAASO observation of gamma rays from a region of ∼2 degrees around the Cassiopeia A (Cas A) supernova remnant to constrain the process of particle escape from this remnant. We dedicate special attention to discuss the impact of shock evolution and particle propagation in the near source region on the gamma ray emission. This is very important to assess the possibility that very high-energy protons may have been accelerated in past activity of Cas A. Given the core collapse nature of Cas A and its young age (∼340 years), the non detection of ≳100 TeV gamma rays from this remnant allows us to draw some conclusions on the role of supernova explosions for the origin of cosmic rays at the knee. In particular we calculate the spectrum of cosmic rays that may have escaped this remnant to make a clear distinction between the instantaneous maximum energy and the one that appears as a flux suppression in the time integrated spectrum from an individual supernova. LHAASO observation of the region around Cas A as well as gamma ray observations of the remnant itself confirm that this remnant is not operating as a PeVatron and that, although in the early stages the maximum energy may have reached ∼Peta-electronVolt, the number of such particles in the surroundings of Cas A is exceedingly small.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188684","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":"Dissociation and destruction of PAHs and PAH clusters induced by absorption of X-rays in protoplanetary discs around T Tauri stars","authors":"K. Lange, C. Dominik, A. G. G. M. Tielens","doi":"10.1051/0004-6361/202347722","DOIUrl":"https://doi.org/10.1051/0004-6361/202347722","url":null,"abstract":"<i>Context<i/>. Only 8% of the protoplanetary discs orbiting a T Tauri star show emission features of polycyclic aromatic hydrocarbons (PAHs). Their abundance is therefore little known. As PAHs are strong absorbers of UV radiation, they contribute to the heating of the disc photosphere, shielding of UV radiation that drives photo-chemistry in the disc, and their abundance is a key parameter for determining the strength of photo-evaporative disc winds. Soon, high-quality data obtained with the James Webb Space Telescope (JWST) will become available with new data to interpret.<i>Aims<i/>. We want to understand the photochemical evolution of PAHs in protoplanetary discs around T Tauri stars, and thus explain the absence of PAH features. We want to determine whether PAHs are destroyed because of the X-ray emission from their host stars or whether PAHs can withstand these conditions.<i>Methods<i/>. We developed a model for the absorption of X-rays by PAHs. X-rays with more energy than the K edge of carbon doubly ionise PAHs and vibrationally excite them by ≈15–35 eV. With a Monte Carlo model, we modelled the dissociation of H, H<sub>2<sub/>, and C<sub>2<sub/>H<sub>2<sub/> from PAH monomers. Furthermore, we modelled the dissociation of PAH clusters and the desorption of PAH clusters from dust grains caused by X-ray excitation.<i>Results<i/>. We find that small PAH clusters quickly desorb and dissociate into individual molecules. PAH molecules experience rapid loss of H and acetylene C<sub>2<sub/>H<sub>2<sub/> by the high excitation and lose C<sub>2<sub/>H<sub>2<sub/> on average after three X-ray excitations. However, large PAH clusters (coronene C<sub>24<sub/>H<sub>12<sub/>: 50 cluster members, circumcoronene C<sub>54<sub/>H<sub>18<sub/>: 3 cluster members) can stay intact and frozen out on dust grains.<i>Conclusions<i/>. Based on our results, we expect a gas-phase PAH abundance that is lower than 0.01 times the ISM abundance and that rapidly decreases over time due to the dissociation of small clusters that are subsequently destroyed. To maintain a higher abundance, replenishment processes such as vertical mixing must exist. Large PAH clusters remain in the disc, frozen out on dust grains, but barely emit PAH features because of their strong thermal coupling to dust grains.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"321 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188718","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":"Scale-invariant vacuum guided resolution of the 7Li BBN problem","authors":"V. G. Gueorguiev","doi":"10.1051/0004-6361/202556334","DOIUrl":"https://doi.org/10.1051/0004-6361/202556334","url":null,"abstract":"A possible resolution of the <sup>7<sup/>Li problem within the scenario of the standard model big bang nucleosynthesis (BNN) is presented. The key idea originates from the application of the scale-invariant vacuum (SIV) paradigm to the BBN. However, here we arrive at the conclusion that reparametrization-invariant symmetry scaling (RISS) is the more appropriate framework for the epoch of the BBN and use the SIV only as a guidance framework. The outcome is a <i>χ<i/><sup>2<sup/> < 0.04 fit to the observed primordial abundances of <sup>4<sup/>He, D/H, <sup>3<sup/>He/D, and a fit of <i>χ<i/><sup>2<sup/> ≈ 1 when including <sup>7<sup/>Li/H observations. The results are obtained and compared to the known standard BBN values by utilizing the publicly available PRIMAT code. The resolution of the <sup>7<sup/>Li problem requires a SIV-guided deviation from the local thermal equilibrium during BBN, such that the thermal energy of matter and radiation scale differently with respect to the SIV-conformal factor <i>λ<i/> during the BBN epoch. This may be viewed as conformal symmetry breaking due to cooling of plasma and the properties of matter, which means that the framework may be of relevance to the problem of nuclear fusion as well. The deduced baryon matter content is Ω<sub><i>b<i/><sub/> ≈ 12% for unbroken SIV and Ω<sub><i>b<i/><sub/> ≈ 38% for partially broken SIV, but with <i>λ<i/> < 1 in both cases, which signals preference for RISS over the conventional SIV viewpoint. Applying the RISS paradigm results in <i>λ<i/> > 1 and Ω<sub><i>b<i/><sub/> ≈ 10% with a clear departure of <i>n<i/><sub><i>T<i/><sub/> from the naive SIV suggested value. In all the cases where the <sup>7<sup/>Li problem is resolved, the baryon content is significantly higher than the usually accepted value of Ω<sub><i>b<i/><sub/> ≈ 4.9% within the Lambda cold dark matter (ΛCDM) model.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"70 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188716","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":"Magnetic reconnection sustains the mass budget of the solar wind","authors":"Yajie Chen, Hardi Peter, Damien Przybylski, Haruhisa Iijima, Lakshmi Pradeep Chitta","doi":"10.1051/0004-6361/202556696","DOIUrl":"https://doi.org/10.1051/0004-6361/202556696","url":null,"abstract":"The solar wind originates from open magnetic field regions on the Sun, but the processes relevant to its origin remain unsolved. We present a self-consistent numerical model of the source region of the wind, in which jets similar to those observed on the Sun naturally emerge due to magnetic reconnection between closed and open magnetic fields. In this process, material is transferred from closed to open field lines and fed into the solar wind. We quantified the mass flux through the magnetic field connected to the heliosphere and found that it greatly exceeds the amount required to sustain the wind. This supports a decades-old suspicion based on spectroscopic observations, indicating that magnetic reconnection in the low solar atmosphere could sustain the solar wind.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"70 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188723","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":"Discovery of the pre-main-sequence eclipsing binary MML 48","authors":"Y. Gómez Maqueo Chew, L. Hebb, H. C. Stempels, F. M. Walter, D. J. James, G. A. Feiden, R. Petrucci, T. Lister, I. Baraffe, M. Brodheim, F. Faedi, D. R. Anderson, R. A. Street, C. Hellier, K. G. Stassun","doi":"10.1051/0004-6361/202555622","DOIUrl":"https://doi.org/10.1051/0004-6361/202555622","url":null,"abstract":"<i>Aims.<i/> We present the discovery of the eclipsing binary MML 48, which is a member of Upper Centaurus Lupus, has an associated age of 16 Myr, and is composed of two young, low-mass stars.<i>Methods.<i/> We used space- and ground-based observations to characterize the system with both time-series photometry and spectroscopy. Given the extreme mass ratio between the stars, <i>q<i/><sub>EB<sub/> = 0.209 ± 0.014, we modeled a single-lined spectroscopic and eclipsing binary system.<i>Results.<i/> The orbital period, 2.0171068 ± 0.0000004 d, is measured from the highest precision light curves. We derive a primary mass of 1.2 ± 0.07 M<sub>⊙<sub/> using stellar models, and with radial velocities we measured a secondary mass of 0.2509 ± 0.0078 M<sub>⊙<sub/>. The radii are large, as expected for pre-main-sequence stars, and are measured as 1.574 ± 0.026 ± 0.050 R<sub>⊙<sub/> and 0.587 ± 0.0095 ± 0.050 R<sub>⊙<sub/>, for the primary and secondary stars, respectively.<i>Conclusions.<i/> MML 48 joins the short list of known low-mass, pre-main-sequence eclipsing binaries (EBs), being one of only five systems with intermediate ages (15−25 Myr), and the system with the most extreme mass ratio. The primary star is currently at the “fusion bump”, undergoing an over-production of energy in the core due to the build-up of <sup>3<sup/>He before reaching its equilibrium abundance set by the proton-proton (p-p) I chain. MML 48 A is the first young star in an eclipsing system that has been found during its fusion bump. MML 48 is thus an important benchmark for low-mass stellar evolution at a time when the stars are rapidly changing, which allows for a tight constraint on the corresponding isochrone given the uneven mass ratio.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"155 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145182867","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}