Astronomy & Astrophysics最新文献

{"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}

{"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}

{"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}

{"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}

{"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}

{"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}

{"title":"Ultrasoft state of microquasar Cygnus X-3: X-ray polarimetry reveals the geometry of the astronomical puzzle","authors":"Alexandra Veledina, Juri Poutanen, Anastasiia Bocharova, Alessandro Di Marco, Sofia V. Forsblom, Fabio La Monaca, Jakub Podgorný, Sergey S. Tsygankov, Andrzej A. Zdziarski, Varpu Ahlberg, David A. Green, Fabio Muleri, Lauren Rhodes, Stefano Bianchi, Enrico Costa, Michal Dovčiak, Vladislav Loktev, Michael McCollough, Paolo Soffitta, Rashid Sunyaev","doi":"10.1051/0004-6361/202451356","DOIUrl":"https://doi.org/10.1051/0004-6361/202451356","url":null,"abstract":"Cygnus X-3 is an enigmatic X-ray binary that is both an exceptional accreting system and a cornerstone for population synthesis studies. Prominent X-ray and radio properties follow a well-defined pattern, and yet the physical reasons for the state changes observed in this system are not known. Recently, the presence of an optically thick envelope around the central source in the hard state was revealed using the X-ray polarization data obtained with the Imaging X-ray Polarimetry Explorer (IXPE). In this work we analyse IXPE data obtained in the ultrasoft (radio quenched) state of the source. The average polarization degree (PD) of 11.9 ± 0.5% at a polarization angle (PA) of 94° ±1° is inconsistent with the simple geometry of the accretion disc viewed at an intermediate inclination. The high PD, the blackbody-like spectrum, and the weakness of fluorescent iron line imply that the central source is hidden behind the optically thick outflow, similar to the hard-state geometry, and its beamed radiation is scattered, by the matter located along the funnel axis, towards our line of sight. In this picture the observed PD is directly related to the source inclination, which we conservatively determine to lie in the range 26° < <i>i<i/> < 28°. Using the new polarimetric properties, we propose a scenario that can be responsible for the cyclic behaviour of the state changes in the binary.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986516","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 rich galactic environment of a H2-absorption-selected quasar","authors":"F. Urbina, P. Noterdaeme, T. A. M. Berg, S. Balashev, S. López, F. Bian","doi":"10.1051/0004-6361/202451236","DOIUrl":"https://doi.org/10.1051/0004-6361/202451236","url":null,"abstract":"We present the first Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) observations of a quasar featuring a proximate molecular absorption system, SDSS J125917.31+030922.5. The proximate damped Ly<i>α<i/> absorption acts as a natural coronagraph, removing the quasar emission over ∼40 Å in wavelength, and allows us to detect extended Ly<i>α<i/> emission without the necessity of subtracting the quasar emission. This natural coronagraph permits the investigation of the quasar environment down to its inner regions (<i>r<i/> < 20 kpc), where galaxy interactions or feedback processes should have the most noticeable effects. Our observations reveal a dense environment, with a highly asymmetric Ly<i>α<i/> emission within 2″ (∼15 kpc), possibly shaped by a companion galaxy, and a southern extension of the nebulae to about 50 kpc, with rotation-like kinematic signature. The width of the Ly<i>α<i/> emission is broadest closer to the quasar, indicating perturbed kinematics as expected if interactions and significant gas flows are present. The foreground absorbing system itself is redshifted by ≈400 km/s relative to the background quasar, and therefore is likely arising from gas moving toward the quasar. Finally two additional Ly<i>α<i/> emitters are detected with > 10<i>σ<i/> significance at 96 and 223 kpc from the quasar, making this field overdense relative to other similar observations of quasars at <i>z<i/> ∼ 3. Our results support the hypothesis that quasars with proximate neutral and molecular absorption trace rich environments where galaxy interactions are at play and motivates further studies of H<sub>2<sub/>-selected quasars to shed light on feeding and feedback processes.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986517","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":"Damping wings in the Lyman-α forest: A model-independent measurement of the neutral fraction at 5.4 < z < 6.1","authors":"Benedetta Spina, Sarah E. I. Bosman, Frederick B. Davies, Prakash Gaikwad, Yongda Zhu","doi":"10.1051/0004-6361/202450798","DOIUrl":"https://doi.org/10.1051/0004-6361/202450798","url":null,"abstract":"<i>Context.<i/> Recent observations have positioned the end point of the Epoch of Reionization (EoR) at a redshift of <i>z<i/> ∼ 5.3. However, observations of the Lyman-<i>α<i/> forest have not yet been able to discern whether reionization occurred slowly and late, with substantial neutral hydrogen persisting at a redshift of ∼6, or rapidly and earlier, with the apparent late end driven by the fluctuating ultraviolet background. Gunn-Peterson (GP) absorption troughs are solid indicators that reionization is not complete until <i>z<i/> = 5.3, but whether they contain significantly neutral gas has not yet been proven.<i>Aims.<i/> We aim to answer this question by directly measuring, for the first time, the neutral hydrogen fraction (<i>x<i/><sub>HI<sub/>) at the end of the EoR (5 ≲ <i>z<i/> ≲ 6) in high-redshift quasar spectra.<i>Methods.<i/> For high neutral fractions, <i>x<i/><sub>HI<sub/> ≳ 0.1, GP troughs exhibit damping wing (DW) absorption extending over 1000 km s<sup>−1<sup/> beyond the troughs. While conclusively detected in Lyman-<i>α<i/> emission lines of quasars at <i>z<i/> ≥ 7, DWs are challenging to observe in the general Lyman-<i>α<i/> forest due to absorption complexities and small-scale stochastic transmission features.<i>Results.<i/> We report the first successful identification of the stochastic DW signal adjacent to GP troughs at redshifts of <i>z<i/> = 5.6 through careful stacking of the dark gaps in the Lyman-<i>α<i/> forest (S/N = 6.3). We use the signal to present a measurement of the corresponding global <i>x<i/><sub>HI<sub/> = 0.19 ± 0.07 at 1<i>σ<i/> (2<i>σ<i/>) at <i>z<i/> = 5.6 and a limit of <i>x<i/><sub>HI<sub/> < 0.44 at <i>z<i/> = 5.9.<i>Conclusions.<i/> The detection of this signal demonstrates the existence of substantially neutral islands near the conclusion of the EoR, unequivocally signaling a late-and-slow reionization scenario.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986584","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":"Rotational synchronisation of B-type binaries in 30 Doradus","authors":"D. J. Lennon, P. L. Dufton, J. I. Villaseñor, N. Langer, C. J. Evans, H. Sana, W. D. Taylor","doi":"10.1051/0004-6361/202450583","DOIUrl":"https://doi.org/10.1051/0004-6361/202450583","url":null,"abstract":"The spin evolution of stars in close binary systems can be strongly affected by tides. We investigate the rotational synchronisation of the stellar components for 69 SB1 systems and 14 SB2 B-type systems in the 30 Doradus region of the Large Magellanic Cloud using observations from the VFTS and BBC surveys. Their orbital periods range from a few to a few hundred days, while estimated primary masses for these systems are in the range ∼5−20 <i>M<i/><sub>⊙<sub/> with mass ratio ranges of <i>q<i/> ∼ 0.03 − 0.5 and <i>q<i/> ∼ 0.6 − 1.0 for the SB1 and SB2 systems, respectively. Projected rotational velocities of the stellar components have been compared with their synchronous velocities derived from the orbital periods. We find that effectively all systems with an orbital period of more than 10 days must be asynchronous, whilst all the systems with periods of less than 3 days are likely synchronised. In terms of the stellar fractional radius (<i>r<i/>), our results imply that all systems with <i>r<i/> < 0.1 are asynchronous, with those having <i>r<i/> > 0.2 probably being synchronised. For the apparently synchronised systems, our results are more consistent with synchronisation at the mean orbital angular velocity rather than with that at periastron.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973934","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}