Astronomy & Astrophysics最新文献

{"title":"ESPRESSO reveals blueshifted neutral iron emission lines on the dayside of WASP-76 b★","authors":"A. R. Costa Silva, O. D. S. Demangeon, N. C. Santos, D. Ehrenreich, C. Lovis, H. Chakraborty, M. Lendl, F. Pepe, S. Cristiani, R. Rebolo, M. R. Zapatero-Osorio, V. Adibekyan, Y. Alibert, R. Allart, C. Allende Prieto, T. Azevedo Silva, F. Borsa, V. Bourrier, E. Cristo, P. Di Marcantonio, E. Esparza-Borges, P. Figueira, J. I. González Hernández, E. Herrero-Cisneros, G. Lo Curto, C. J. A. P. Martins, A. Mehner, N. J. Nunes, E. Palle, S. Pelletier, J. V. Seidel, A. M. Silva, S. G. Sousa, A. Sozzetti, M. Steiner, A. Suárez Mascareño, S. Udry","doi":"10.1051/0004-6361/202449935","DOIUrl":"https://doi.org/10.1051/0004-6361/202449935","url":null,"abstract":"<i>Context.<i/> Ultra hot Jupiters (gas giants with <i>T<i/><sub>eq<sub/> > 2000 K) are intriguing exoplanets due to the extreme physics and chemistry present in their atmospheres. Their torrid daysides can be characterised using ground-based high-resolution emission spectroscopy.<i>Aims.<i/> We search for signatures of neutral and singly ionised iron (Fe I and Fe II, respectively) in the dayside of the ultra hot Jupiter WASP-76 b, as these species were detected via transmission spectroscopy in this exoplanet. Furthermore, we aim to confirm the existence of a thermal inversion layer, which has been reported in previous studies, and attempt to constrain its properties.<i>Methods.<i/> We observed WASP-76 b on four epochs with ESPRESSO at the VLT, at orbital phases shortly before and after the secondary transit, when the dayside is in view. We present the first analysis of high-resolution optical emission spectra for this exoplanet. We compare the data to synthetic templates created with petitRADTRANS, using cross-correlation function techniques.<i>Results.<i/> We detect a blueshifted (−4.7 ± 0.3 km s<sup>−1<sup/>) Fe I emission signature on the dayside of WASP-76 b at 6.0<i>σ<i/>. The signal is detected independently both before and after the eclipse, and it is blueshifted in both cases. The presence of iron emission features confirms the existence of a thermal inversion layer. Fe II was not detected, possibly because this species is located in the upper layers of the atmosphere, which are more optically thin. Thus the Fe II signature on the dayside of WASP-76 b is too weak to be detected with emission spectroscopy.<i>Conclusions.<i/> We propose that the blueshifted Fe I signature is created by material rising from the hot spot to the upper layers of the atmosphere, and discuss possible scenarios related to the position of the hotspot. This work unveils some of the dynamic processes ongoing on the dayside of the ultra hot Jupiter WASP-76 b through the analysis of the Fe I signature from its atmosphere, and complements previous knowledge obtained from transmission studies. It also highlights the ability of ESPRESSO to probe the dayside of this class of exoplanets.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142142407","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":"Exocomet orbital distribution around β Pictoris","authors":"René Heller","doi":"10.1051/0004-6361/202244087","DOIUrl":"https://doi.org/10.1051/0004-6361/202244087","url":null,"abstract":"The ~23 Myr young star <i>β<i/> Pictoris (<i>β<i/> Pic) is a laboratory for planet formation studies because of its observed debris disk, its directly imaged super-Jovian planets <i>β<i/> Pic b and c, and the evidence of extrasolar comets that regularly transit in front of the star. The most recent evidence of exocometary transits around <i>β<i/> Pic came from stellar photometric time series obtained with the TESS space mission. Previous analyses of these transits constrained the orbital distribution of the underlying exocomet population to a range between about 0.03 and 1.3 AU assuming a fixed transit impact parameter. We examine the distribution of the observed transit durations (Δ<i>t<i/>) to infer the orbital surface density distribution (<i>δ<i/>) of the underlying exocomet sample. The effect of the geometric transit probability for circular orbits was properly taken into account, but we assumed that the radius of the transiting comets and their possible clouds of evaporating material are much smaller than the stellar radius. We show that a narrow belt of exocomets around <i>β<i/> Pic, in which the transit impact parameters are randomized but the orbital semimajor axes are equal, results in a pile-up of long transit durations. This is in contrast to observations, which reveal a pile-up of short transit durations (Δ<i>t<i/> ≈ 0.1 d) and a tail of only a few transits with Δ<i>t<i/> > 0.4 d. A flat density distribution of exocomets between about 0.03 and 2.5 AU results in a better match between the resulting Δ<i>t<i/> distribution and the observations, but the slope of the predicted Δ<i>t<i/> histogram is not sufficiently steep. An even better match to the observations can be produced with a <i>δ ∝ a<sup>β<sup/><i/> power law. Our modeling reveals a best fit between the observed and predicted Δ<i>t<i/> distribution for <i>β<i/> = −0.15<sub>−0.10<sub/><sup>+0.05<sup/>. A more reasonable scenario in which the exocometary trajectories are modeled as hyperbolic orbits can also reproduce the observed Δ<i>t<i/> distribution to some extent. Future studies might reproduce the observed Δ<i>t<i/> distribution with a full exploration of the four-dimensional parameter space of highly eccentric orbits, and they might need to relax our assumption that the transiting objects are smaller than the stellar disk. The number of observed exocometary transits around <i>β<i/> Pic is currently too small to validate the previously reported distinction of two distinct exocomet families, but this might be possible with future TESS observations of this star. Our results nevertheless imply that cometary material exists on highly eccentric orbits with a more extended range of semimajor axes than suggested by previous spectroscopic observations.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142142408","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":"Into the depths: Unveiling ELAIS-N1 with LOFAR’s deepest sub-arcsecond wide-field images","authors":"J. M. G. H. J. de Jong, R. J. van Weeren, F. Sweijen, J. B. R. Oonk, T. W. Shimwell, A. R. Offringa, L. K. Morabito, H. J. A. Röttgering, R. Kondapally, E. L. Escott, P. N. Best, M. Bondi, H. Ye, J. W. Petley","doi":"10.1051/0004-6361/202450595","DOIUrl":"https://doi.org/10.1051/0004-6361/202450595","url":null,"abstract":"We present the deepest wide-field 115–166 MHz image at sub-arcsecond resolution spanning an area of 2.5° × 2.5° centred at the ELAIS-N1 deep field. To achieve this, we improved the direction-independent (DI) and direction-dependent (DD) calibrations for the International LOw Frequency ARray (LOFAR) Telescope. This enhancement enabled us to efficiently process 32 h of data from four different 8-h observations using the high-band antennas (HBAs) of all 52 stations, covering baselines up to approximately 2000 km across Europe. The DI calibration was improved by using an accurate sky model and refining the series of calibration steps on the in-field calibrator, while the DD calibration was improved by adopting a more automated approach for selecting the DD calibrators and inspecting the self-calibration on these sources. For our brightest calibrators, we also added an additional round of self-calibration for the Dutch core and remote stations in order to refine the solutions for shorter baselines. To complement our highest resolution at 0.3″, we also made intermediate resolution wide-field images at 0.6″ and 1.2″. Our resulting wide-field images achieve a central noise level of 14 μJy beam<sup>−1<sup/> at 0.3″, doubling the depth and uncovering four times more objects than the Lockman Hole deep field image at comparable resolution but with only 8 h of data. Compared to LOFAR imaging without the international stations, we note that due to the increased collecting area and the absence of confusion noise, we reached a point-source sensitivity comparable to a 500-h ELAIS-N1 6″ image with 16 times less observing time. Importantly, we have found that the computing costs for the same amount of data are almost halved (to about 139 000 CPU h per 8 h of data) compared to previous efforts, though they remain high. Our work underscores the value and feasibility of exploiting all Dutch and international LOFAR stations to make deep wide-field images at sub-arcsecond resolution.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142131017","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":"Symbiotic stars in X-rays","authors":"I. J. Lima, G. J. M. Luna, K. Mukai, A. S. Oliveira, J. L. Sokoloski, F. M. Walter, N. Palivanas, N. E. Nuñez, R. R. Souza, R. A. N. Araujo","doi":"10.1051/0004-6361/202449913","DOIUrl":"https://doi.org/10.1051/0004-6361/202449913","url":null,"abstract":"White dwarf symbiotic binaries are detected in X-rays with luminosities in the range of 10<sup>30<sup/>–10<sup>34<sup/> ergs s<sup>−1<sup/>. Their X-ray emission arises either from the accretion disk boundary layer, from a region where the winds from both components collide, or from nuclear burning on the surface of the white dwarf (WD). In our continuous effort to identify X-ray-emitting symbiotic stars, we studied four systems using observations from the <i>Neil Gehrels Swift<i/> Observatory and <i>XMM-Newton<i/> satellites in X-rays and from Transiting Exoplanet Survey Satellite (TESS) in the optical. The X-ray spectra were fit with absorbed optically thin thermal plasma models that are either single- or multitemperature with <i>kT<i/> < 8 keV for all targets. Based on the characteristics of their X-ray spectra, we classified BD Cam as possible <i>β<i/>-type, V1261 Ori and CD −27 8661 as <i>δ<i/>-type, and confirmed NQ Gem as <i>β<i/>/<i>δ<i/>-type. The <i>δ<i/>-type X-ray emission most likely arises from the boundary layer of the accretion disk, while in the case of BD Cam, its mostly soft emission originates from shocks, possibly between the red giant and WD and disk winds. In general, we find that the observed X-ray emission is powered by accretion at a low accretion rate of about 10<sup>−11<sup/> M<sub>⊙<sub/> yr<sup>−1<sup/>. The low ratio of X-ray to optical luminosities, however indicates that the accretion-disk boundary layer is mostly optically thick and tends to emit in the far or extreme UV. The detection of flickering in optical data provides evidence of the existence of an accretion disk.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142131071","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 𝒯ℛ𝒪𝒴 project","authors":"O. Balsalobre-Ruza, J. Lillo-Box, D. Barrado, A. C. M. Correia, J. P. Faria, P. Figueira, A. Leleu, P. Robutel, N. Santos, E. Herrero-Cisneros","doi":"10.1051/0004-6361/202450717","DOIUrl":"https://doi.org/10.1051/0004-6361/202450717","url":null,"abstract":"<i>Context.<i/> Co-orbital objects, also known as trojans, are frequently found in simulations of planetary system formation. In these configurations, a planet shares its orbit with other massive bodies. It is still unclear why there have not been any co-orbitals discovered thus far in exoplanetary systems (exotrojans) or even pairs of planets found in such a 1:1 mean motion resonance. Reconciling observations and theory is an open subject in the field.<i>Aims.<i/> The main objective of the 𝒯ℛ𝒪𝒴 project is to conduct an exhaustive search for exotrojans using diverse observational techniques. In this work, we analyze the radial velocity time series informed by transits, focusing the search around low-mass stars.<i>Methods.<i/> We employed the <i>α<i/>-test method on confirmed planets searching for shifts between spectral and photometric mid-transit times. This technique is sensitive to mass imbalances within the planetary orbit, allowing us to identify non-negligible co-orbital masses.<i>Results.<i/> Among the 95 transiting planets examined, we find one robust exotrojan candidate with a significant 3-σ detection. Additionally, 25 exoplanets show compatibility with the presence of exotrojan companions at a 1-<i>σ<i/> level, requiring further observations to better constrain their presence. For two of those weak candidates, we find dimmings in their light curves within the predicted Lagrangian region. We established upper limits on the co-orbital masses for either the candidates and null detections.<i>Conclusions.<i/> Our analysis reveals that current high-resolution spectrographs effectively rule out co-orbitals more massive than Saturn around low-mass stars. This work points out to dozens of targets that have the potential to better constraint their exotrojan upper mass limit with dedicated radial velocity observations. We also explored the potential of observing the secondary eclipses of the confirmed exoplanets in our sample to enhance the exotrojan search, ultimately leading to a more accurate estimation of the occurrence rate of exotrojans.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142131016","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":"Weighing Milky Way and Andromeda in an expanding ΛCDM Universe","authors":"David Benisty","doi":"10.1051/0004-6361/202449884","DOIUrl":"https://doi.org/10.1051/0004-6361/202449884","url":null,"abstract":"The dynamics of the Local Group (LG), especially the contribution of the Milky Way (MW) and Andromeda (M 31) galaxies, is sensitive to the presence of dark energy. This work analyzes the evolution of the LG by considering it as a two-body problem in a homogeneous and isotropic expanding spacetime in a full Λcold dark matter (ΛCDM) background. Using the timing argument (TA), which links LG dynamics to LG mass, we find that the full ΛCDM background predicts a ∼10% lower mass for the LG; whereas Λ alone predicts a ∼10% higher mass. The TA mass is modified by (i) simulations and (ii) the effect of the Large Magellanic Cloud (LMC) to alleviate the poorly constrained internal mass distributions of M 31 and the MW, their time evolution, and the unknown distribution of dark matter between them. First, using IllustrisTNG simulations, we accounted for the effects of two extended halos and their environment (rather than point particles) and predicted their mass (3.89 ± 0.62)×10<sup>12<sup/> <i>M<i/><sub>⊙<sub/>. Second, the LMC effectively changes the separation and velocities of M 31 towards the MW and reduces the predicted mass to (2.33 ± 0.72)×10<sup>12<sup/> <i>M<i/><sub>⊙<sub/>. Despite the uncertainties around dark matter between these galaxies, the overall estimated mass is compatible with the mere sum of the MW and M 31 masses. The total mass of the TA is compatible with other estimates, such as the Hubble flow and the Virial Theorem with other dwarf galaxies. The combined result shows, for the first time, that a lower mass estimate can be obtained from the TA, with a consistent embedding and other systematic effects, and without an additional dark matter halo around the galaxies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118129","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":"Gas-rich “ultra-diffuse” galaxies are consistent with the baryonic Tully–Fisher relation and with Milgromian dynamics","authors":"F. Lelli","doi":"10.1051/0004-6361/202451289","DOIUrl":"https://doi.org/10.1051/0004-6361/202451289","url":null,"abstract":"Some gas-rich “ultra-diffuse” galaxies (UDGs), which are extreme examples of low surface brightness (LSB) dwarf galaxies, have been reported to lack dark matter and to be offset from the baryonic Tully–Fisher relation (BTFR). If confirmed, these UDGs would represent a serious challenge for both ΛCDM galaxy-formation models and Milgromian dynamics. Here I demonstrate that these conclusions are very dubious due to underestimated uncertainties on inclinations and/or distances. First, I show that UDGs are offset from the BTFR in the same way as usual face-on LSB dwarfs due to systematic biases at low inclinations. Next, I analyze the two UDGs with the best available rotation-curve data. The first (AGC 242019) is ideally inclined for kinematic studies; MOND can fit the observed rotation curve with a distance of 12.5 ± 0.6 Mpc, which is consistent with Virgocentric flow models. The second UDG (AGC 114905) is close to face-on, so not ideal for kinematic studies; MOND can fit the observed rotation curve with a distance of 68 ± 13 Mpc and inclination of 15° ±2°, which are consistent with existing data. In particular, I show that the disk inclination is more uncertain than previously estimated due to significant asymmetries (lopsidedness) in the stellar distribution. In conclusion, there is no strong evidence that gas-rich UDGs and gas-rich LSB dwarfs are distinct galaxy populations with different dynamical properties; instead, UDGs seem to be a subset of LSB dwarf galaxies biased toward face-on systems.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118094","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":"FAUST","authors":"M. J. Maureira, J. E. Pineda, H. B. Liu, L. Testi, D. Segura-Cox, C. Chandler, D. Johnstone, P. Caselli, G. Sabatini, Y. Aikawa, E. Bianchi, C. Codella, N. Cuello, D. Fedele, R. Friesen, L. Loinard, L. Podio, C. Ceccarelli, N. Sakai, S. Yamamoto","doi":"10.1051/0004-6361/202451166","DOIUrl":"https://doi.org/10.1051/0004-6361/202451166","url":null,"abstract":"<i>Context.<i/> Planets form in the disks surrounding young stars. The time at which the planet formation process begins is still an open question. Annular substructures such as rings and gaps in disks are intertwined with planet formation, and thus their presence or absence is commonly used to investigate the onset of this process.<i>Aims.<i/> Current observations show that a limited number of disks surrounding protostars exhibit annular substructures, all of them in the Class I stage. The lack of observed features in most of these sources may indicate a late emergence of substructures, but it could also be an artifact of these disks being optically thick. To mitigate the problem of optical depth, we investigated substructures within a very young Class 0 disk characterized by low inclination using observations at longer wavelengths.<i>Methods.<i/> We used 3 mm ALMA observations tracing dust emission at a resolution of 7 au to search for evidence of annular substructures in the disk around the deeply embedded Class 0 protostar Oph A SM1.<i>Results.<i/> The observations reveal a nearly face-on disk (inclination ∼ 16°) extending up to 40 au. The radial intensity profile shows a clear deviation from a smooth profile near 30 au, which we interpret as the presence of either a gap at 28 au or a ring at 34 au with Gaussian widths of au and au, respectively. Crucially, the 3 mm emission at the location of the possible gap or ring is determined to be optically thin, precluding the possibility that this feature in the intensity profile is due to the emission being optically thick.<i>Conclusions.<i/> Annular substructures resembling those in the more evolved Class I and II disks could indeed be present in the Class 0 stage, which is earlier than suggested by previous observations. Similar observations of embedded disks in which the high-optical-depth problem can be mitigated are clearly needed to better constrain the onset of substructures in the embedded stages.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118095","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":"X-Shooting ULLYSES: Massive stars at low metallicity","authors":"A. A. C. Sander, J.-C. Bouret, M. Bernini-Peron, J. Puls, F. Backs, S. R. Berlanas, J. M. Bestenlehner, S. A. Brands, A. Herrero, F. Martins, O. Maryeva, D. Pauli, V. Ramachandran, P. A. Crowther, V. M. A. Gómez-González, A. C. Gormaz-Matamala, W.-R. Hamann, D. J. Hillier, R. Kuiper, C. J. K. Larkin, R. R. Lefever, A. Mehner, F. Najarro, L. M. Oskinova, E. C. Schösser, T. Shenar, H. Todt, A. ud-Doula, J. S. Vink","doi":"10.1051/0004-6361/202449829","DOIUrl":"https://doi.org/10.1051/0004-6361/202449829","url":null,"abstract":"<i>Context.<i/> The spectral analysis of hot, massive stars is a fundamental astrophysical method of determining their intrinsic properties and feedback. With their inherent, radiation-driven winds, the quantitative spectroscopy for hot, massive stars requires detailed numerical modeling of the atmosphere and an iterative treatment in order to obtain the best solution within a given framework.<i>Aims.<i/> We present an overview of different techniques for the quantitative spectroscopy of hot stars employed within the X-Shooting ULLYSES collaboration, ranging from grid-based approaches to tailored spectral fits. By performing a blind test for selected targets, we gain an overview of the similarities and differences between the resulting stellar and wind parameters. Our study is not a systematic benchmark between different codes or methods; our aim is to provide an overview of the parameter spread caused by different approaches.<i>Methods.<i/> For three different stars from the XShooting ULLYSES sample (SMC O5 star AzV 377, LMC O7 star Sk -69° 50, and LMC O9 star Sk-66° 171), we employ different stellar atmosphere codes (CMFGEN, Fastwind, PoWR) and different strategies to determine their best-fitting model solutions. For our analyses, UV and optical spectroscopy are used to derive the stellar and wind properties with some methods relying purely on optical data for comparison. To determine the overall spectral energy distribution, we further employ additional photometry from the literature.<i>Results.<i/> The effective temperatures found for each of the three different sample stars agree within 3 kK, while the differences in log <i>g<i/> can be up to 0.2 dex. Luminosity differences of up to 0.1 dex result from different reddening assumptions, which seem to be systematically larger for the methods employing a genetic algorithm. All sample stars are found to be enriched in nitrogen. The terminal wind velocities are surprisingly similar and do not strictly follow the <i>u<i/><sub>∞<sub/>−<i>T<i/><sub>eff<sub/> relation.<i>Conclusions.<i/> We find reasonable agreement in terms of the derived stellar and wind parameters between the different methods. Tailored fitting methods tend to be able to minimize or avoid discrepancies obtained with coarser or increasingly automatized treatments. The inclusion of UV spectral data is essential for the determination of realistic wind parameters. For one target (Sk -69° 50), we find clear indications of an evolved status.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118096","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":"Impediments to the cosmic growth of galaxies: The outflow budget from Star Formation and Active Galactic Nuclei","authors":"Johannes Buchner","doi":"10.1051/0004-6361/202451170","DOIUrl":"https://doi.org/10.1051/0004-6361/202451170","url":null,"abstract":"The gas reservoir of galaxies can be altered by outflows that are driven by star formation and luminous active galactic nuclei. Jets heating the surroundings of host galaxies can also prevent the gas from cooling and prevent inflows. Spectacular examples for these three mass-displacement channels have been observed, but their importance in transforming the galaxy population depends on the occurrence rates of the outflow triggers. We investigate the absolute and relative importance of these three channels. In an observation-driven approach, we combined distribution functions and scaling relations to empirically compare average outflow rates across the total stellar mass spectrum of the galaxy and across cosmic time. This hinges on local outflow studies, which should be extended to systematic, large, and diverse samples, and we did not consider a halo-heating effect by radiation-driven outflows so far. Independent of simulations, our results show the dominance of star formation-driven outflows in low-mass galaxies. Massive galaxies today are predominately prevented from growing further by jet heating, while at <i>z<i/> = 1 − 3, all three processes are approximately similarly important. Over the full mass spectrum and cosmic history, outflows driven by the radiation from active galactic nuclei are never the dominant process.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118090","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}