Astronomy & Astrophysics最新文献

{"title":"A binary supernova OB-runaway candidate inside Berkeley 97","authors":"B. Dinçel, S. Sheth, L. Specht, S. Hellmund, L. J. Eberle, M. Mugrauer, R. Neuhäuser, K.-U. Michel","doi":"10.1051/0004-6361/202449657","DOIUrl":"https://doi.org/10.1051/0004-6361/202449657","url":null,"abstract":"<i>Aims.<i/> OB-runaway stars ejected by the binary supernova mechanism can be found near young open star clusters. In this paper, we present an OB-runaway candidate as a pre-SN binary companion to the progenitor of the pulsar PSR J2238+5903 inside the young open star cluster Berkeley 97.<i>Methods.<i/> We tried to find a kinematic outlier based on <i>Gaia<i/> DR3 proper motions and parallaxes to be the pre-supernova binary companion to the progenitor of the pulsar. We took the spectra of two bright early B-type stars of the cluster, determined their effective temperature and surface gravity, and updated the parameters of the cluster. Through isochrone fitting of the color-magnitude diagram of the star cluster, we identified the members and determined the stellar parameters of the runaway star.<i>Results.<i/> Two bright members of the cluster, HD 240015 and HD 240016, are massive stars with spectral types of B0.5II and B1.5II and effective temperatures of <i>T<i/><sub>eff<sub/> = 21 000 ± 1000 K and <i>T<i/><sub>eff<sub/> = 24 000 ± 2000 K, respectively, as well as surface gravities of . We find that Berkeley 97 is a star cluster with an age of , an uncertainty of < 0.1 dex, and an interstellar extinction of <i>A<i/><sub>V<sub/> = 3.1 ± 0.1 mag. The runaway star has an effective temperature of <i>T<i/><sub>eff<sub/> = 12 250 ± 1750 K with a surface gravity of (B8V type star). By tracing back the proper motion of the runaway star, the explosion center was found for different possible pulsar ages of 10, 20, and 26.6 kyr. The pulsar moving out from the 20 kyr position must have a space velocity of ∼340 km s<sup>−1<sup/>, which is consistent with the general pulsar velocity distribution. This supports the idea that the pulsar originated from the cluster as a result of a binary supernova. Despite its young age, <i>τ<i/> < 26.6 kyr, the supernova remnant is not visible.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541810","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":"Alcock–Paczyński effect on void-finding","authors":"Slađana Radinović, Hans A. Winther, Seshadri Nadathur, Will J. Percival, Enrique Paillas, Tristan Sohrab Fraser, Elena Massara, Alex Woodfinden","doi":"10.1051/0004-6361/202451358","DOIUrl":"https://doi.org/10.1051/0004-6361/202451358","url":null,"abstract":"Under the assumption of statistical isotropy, and in the absence of directional selection effects, a stack of voids is expected to be spherically symmetric, which makes it an excellent object to use for an Alcock–Paczyński (AP) test. This test is commonly carried out using the void-galaxy cross-correlation function (CCF), which has emerged as a competitive probe, especially in combination with the galaxy-galaxy auto-correlation function. Current studies of the AP effect around voids assume that void-centre positions are influenced by the choice of fiducial cosmology in the same way as galaxy positions. We show that this assumption, though prevalent in the literature, is complicated by the response of void-finding algorithms to shifts in tracer positions. Using stretched simulation boxes to emulate the AP effect, we investigate how the void-galaxy CCF changes due to its presence, revealing an additional effect imprinted in the CCF that must be accounted for. The effect originates from the response of void finders to the distorted tracer field – which leads to reduction of the amplitude of the AP signal in the CCF – and thus depends on the specific void-finding algorithm used. We present results for four different void-finding packages, namely REVOLVER, VIDE, voxel, and the spherical void finder in the Pylians3 library, demonstrating how incorrect treatment of the AP effect results in biases in the recovered parameters, regardless of the technique used. Finally, we propose a method to alleviate this issue without resorting to complex and finder-specific modelling of the void-finder response to AP.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"87 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541759","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":"Polarization of active galactic nuclei with significant VLBI-Gaia displacements","authors":"Dmitry Blinov, Arina Arshinova","doi":"10.1051/0004-6361/202451186","DOIUrl":"https://doi.org/10.1051/0004-6361/202451186","url":null,"abstract":"<i>Context.<i/> Numerous studies have reported significant displacements in the coordinates of active galactic nuclei (AGNs) between measurements using the very-long-baseline-interferometry (VLBI) technique and those obtained by the <i>Gaia<i/> space observatory. There is consensus that these discrepancies do indeed manifest astrometrically resolved sub-components of AGNs rather than random measurement noise. Among other evidence, it has been reported that AGNs with VLBI-to-<i>Gaia<i/> displacements (VGDs) pointing downstream of their parsec-scale radio jets exhibit higher optical polarization compared to sources with the opposite (upstream) VGD orientation.<i>Aims.<i/> We aim to verify the previously reported connection between optical polarization and a VGD-jet angle using a larger dataset of polarimetric measurements and updated <i>Gaia<i/> DR3 positions. We also seek further evidence supporting the disk-jet dichotomy as an explanation of such a connection by using millimeter-wave polarization and multiband optical polarization measurements.<i>Methods.<i/> We performed optical polarimetric observations of 152 AGNs using three telescopes. These data are complemented by other publicly available polarimetric measurements of AGNs. We cross-matched public astrometric data from VLBI and <i>Gaia<i/> experiments, obtained corresponding positional displacements, and combined this catalog with the polarimetric and jet direction data.<i>Results.<i/> Active galactic nuclei with downstream VGDs are confirmed to have significantly higher optical fractional polarization than the upstream sample. At the same time, the millimeter-wavelength polarization of the two samples shows very similar distributions.<i>Conclusions.<i/> Our results support the hypothesis that the VGDs pointing down the radio jet are likely caused by a component in the jet emitting highly polarized synchrotron radiation and dominating in the overall optical emission. The upstream-oriented VGDs are likely to be produced by the low-polarization emission of the central engine’s subcomponents, which dominate in the optical.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541811","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":"Merging galaxies in isolated environments","authors":"Paula Calderón-Castillo, Rory Smith","doi":"10.1051/0004-6361/202450473","DOIUrl":"https://doi.org/10.1051/0004-6361/202450473","url":null,"abstract":"<i>Context.<i/> It is now well known that certain massive galaxies undergo enormous enhancements in their star formation rate (SFR) when they undergo major mergers. These enhancements can be as high as 100 times the SFR of unperturbed galaxies of the same stellar mass. Previous works have found that the size of this boost in star formation (SF) is related to the morphology of and the proximity to the companion. The same trend has also been observed for the fraction of active galactic nuclei (AGN), where galaxies that are closer together tend to have higher AGN fractions.<i>Aims.<i/> We aim to analyse the SF enhancement and AGN fraction evolution during the merger process by using a more timeline-like merger sequence. Additionally, we aim to determine the relation between the SF enhancement in mergers and the morphology of the galaxies involved.<i>Methods.<i/> Taking advantage of the stellar masses (<i>M<i/><sub>*<sub/>) and SFRs of the ∼600 nearby isolated mergers obtained in our previous study, we calculated the distance of each of our galaxies from the star-forming main sequence (MS; specific SFR (sSFR)/sSFR<sub>MS<sub/>), which werefer to as the SF mode. We then analysed how the SF mode varies during the merger process as a function of morphology and <i>M<i/><sub>*<sub/>. Additionally, we analysed the AGN content of our mergers, using multiple diagnostics based on emission line ratios and WISE colours.<i>Results.<i/> We observed that, overall, merging galaxies show an SF mode that is governed by their morphology. Spirals typically show high SF mode values, while highly disturbed (HD) galaxies are generally even more enhanced (median values of +0.8 dex and +1.08 dex above the MS, respectively). In contrast, elliptical and lenticular galaxies show the lowest SF modes, as expected. However, even they show SF enhancement compared to their unperturbed counterparts. For example, their median SF mode is just within the 1-sigma scatter of the MS, and this can occur even before the galaxies have coalesced. We observed a trend for the SF mode to gradually increase with increasing merger stage. We did not find a clear dependency of the observed AGN fraction on the merger stage for the majority of our classification methods.<i>Conclusions.<i/> We find mergers can significantly enhance SF in galaxies of all morphologies. For early-type galaxies, this could suggest that some gas was present prior to the merger, which may be triggered to form stars by the tidal interaction. As the SF enhancement continues throughout the merger process, this suggests that the enhancement may be a long-lived event, contrary to the short starbursts seen in some models.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541809","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":"Hidden by a star: The redshift and the offset broad line of the flat-spectrum radio quasar PKS 0903–57⋆","authors":"P. Goldoni, C. Boisson, S. Pita, F. D’Ammando, E. Kasai, W. Max-Moerbeck, M. Backes, G. Cotter","doi":"10.1051/0004-6361/202451609","DOIUrl":"https://doi.org/10.1051/0004-6361/202451609","url":null,"abstract":"<i>Context.<i/> PKS 0903−57 is a little-studied <i>γ<i/>-ray blazar that has recently attracted considerable interest due to the strong flaring episodes observed since 2020 in high energy (HE; 100 MeV ≤ <i>E<i/> ≤ 100 GeV) and very high-energy (VHE; 100 GeV ≤ <i>E<i/> ≤ 10 TeV) <i>γ<i/>-rays. Its nature and properties are still not well determined. In particular, it is unclear whether PKS 0903−57 is a BL Lac or a flat-spectrum radio quasar (FSRQ), while its redshift estimation relies on a possibly misassociated low signal-to-noise ratio spectrum.<i>Aims.<i/> Our aims were to reliably measure the redshift of the blazar, and to determine its spectral type and luminosity in the optical range.<i>Methods.<i/> We performed spectroscopy of the optical counterpart of the blazar using the South African Large Telescope (SALT) and the Very Large Telescope (VLT), and monitored it photometrically with the Rapid Eye Mount (REM) telescope.<i>Results.<i/> We firmly measured the redshift of the blazar as <i>z<i/> = 0.2621 ± 0.0006 thanks to the detection of five narrow optical lines. The detection of a symmetric broad H<i>α<i/> line with full width at half maximum (FWHM) of 4020 ± 30 km/s together with a jet-dominated continuum leads us to classify it as a FSRQ. Finally, we detected with high significance a redshift offset (∼1500 km/s) between the broad line and the host. This is the first time that such an offset has been unequivocally detected in a VHE blazar, possibly pointing to a very peculiar accretion configuration, a merging system, or a recoiling black hole.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"209 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541756","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":"Diffuse interstellar bands as dust indicators: The contribution from 3D maps","authors":"R. Lallement, J. L. Vergely, N. L. J. Cox","doi":"10.1051/0004-6361/202451657","DOIUrl":"https://doi.org/10.1051/0004-6361/202451657","url":null,"abstract":"&lt;i&gt;Context.&lt;i/&gt; Three-dimensional (3D) distributions of the 862 nm diffuse interstellar band (DIB) carrier have been computed based on &lt;i&gt;Gaia&lt;i/&gt; parallaxes and DIB catalogues, in parallel with 3D maps of dust extinction density. Three-dimensional maps provide local diagnostics and information on the distribution of structures in addition to line-of-sight (LOS) integrated quantities, and allow us to focus on poorly studied low-extinction areas. They make cross-matching with other catalogues possible through estimates of the DIB and extinction along any given path.&lt;i&gt;Aims.&lt;i/&gt; We re-examined the relationships between the density of DIB carriers and the absorption and emission properties of spatially co-located dust. Along with laboratory identifications of carriers, these properties may shed light on the formation and evolution of this organic matter. They may also help to model dust emission and absorption properties in a more detailed way.&lt;i&gt;Methods.&lt;i/&gt; We used the 3D maps of 862 nm DIBs and of dust extinction, as well as available DIB equivalent width (EW) catalogues and published measurements of parameters characterizing the dust extinction law and the dust emission. We studied the relationships between the extinction-normalized 862 nm DIB EW and the extinction level, the total-to-selective extinction ratio &lt;i&gt;R&lt;sub&gt;V&lt;sub/&gt;&lt;i/&gt;, and the dust far-IR emission spectral index &lt;i&gt;β.&lt;i/&gt; We re-visited the link between several DIBs and the UV absorption bump at 220 nm.&lt;i&gt;Results.&lt;i/&gt; The ratio of the 862 nm DIB carrier density to the optical extinction density (DIB&lt;sub&gt;norm&lt;sub/&gt;&lt;sup&gt;862&lt;sup/&gt;) is increasing in low-density clouds, confirming with local values the trend seen in the LOS data. In both cases, the coefficients of a fitted power law fall within the range of those measured towards SDSS high-latitude targets for 20 different bands, ranking this DIB among those with a high increase, above that of the broad 4430 Å DIB. This is consistent with the recent measurement of a larger scale height above the Plane for the 862 nm DIB compared to that of the 4430 Å DIB. Using map-integrated 862 nm DIB EWs and extinctions along the paths to APOGEE targets with published proxies &lt;i&gt;R&lt;i/&gt;′&lt;sub&gt;V&lt;sub/&gt; for the total-to-selective extinction ratio, we found that, despite a large scatter, DIB&lt;sub&gt;norm&lt;sub/&gt;&lt;sup&gt;862&lt;sup/&gt; is positively correlated with &lt;i&gt;R&lt;i/&gt;′&lt;sub&gt;V&lt;sub/&gt; for those stars with low to moderate extinctions (&lt;i&gt;A&lt;sub&gt;V&lt;sub/&gt;&lt;i/&gt; = 0.2 to 2–3 mag). Independently, using stars from the 862 nm DIB catalogue located outside the disk and for the same regime of extinction, DIB&lt;sub&gt;norm&lt;sub/&gt;&lt;sup&gt;862&lt;sup/&gt; is found to be globally anti-correlated with the Planck opacity spectral index &lt;i&gt;β.&lt;i/&gt; This is consistent with the observed anti-correlation between &lt;i&gt;β&lt;i/&gt; and &lt;i&gt;R&lt;i/&gt;′&lt;sub&gt;V&lt;sub/&gt;. In the light of a recent result on the variability of the carbon/silicate ratio in dust grains as a source of this anti-correlation, it suggests that DIB&lt;sub&gt;norm&lt;sub/","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"19 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541808","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":"Investigating the consistency of the shape and flux of X-ray reflection spectra in the hard state with an accretion disk reaching close to the black hole","authors":"Sudeb Ranjan Datta, Michal Dovčiak, Michal Bursa, Wenda Zhang, Jiří Horák, Vladimír Karas","doi":"10.1051/0004-6361/202450352","DOIUrl":"https://doi.org/10.1051/0004-6361/202450352","url":null,"abstract":"<i>Context.<i/> The observed spectra from black hole (BH) X-ray binaries (XRBs) typically consist of two primary components. A multitemperature blackbody originating from the accretion disk in the soft X-ray, and a power law-like component in the hard X-ray, due to the Comptonization of soft photons by the hot corona. The illumination of the disk by the corona gives rise to another key component known as reflection. A fraction of the incident hard X-ray radiation is naturally absorbed and re-emitted as a blackbody at lower energies and referred to as the “reprocessed blackbody”.<i>Aims.<i/> For densities relevant to XRBs and typical ionization values, the reprocessed blackbody may become significant in the soft X-ray region (approximately 0.1–1.0 keV) and should be noticeable in the observed spectra as a consequence of reflection. The absence of any blackbody component in the low/hard state of a BH XRB may not be consistent with the reflection of highly irradiating flux, observed as a power law from an appropriately dense disk of XRB.<i>Methods.<i/> We focus on the low/hard state of the BH XRB MAXI J1820+070. In contrast to previous works, we simultaneously fit the shape and flux of the reflection spectra. This allowed us to estimate the correct density and ionization of the slab as well as the corresponding reprocessed blackbody.<i>Results.<i/> Our fitting of the representative observation of the BH XRB low/hard state suggests that the disk may, in principle, extend very close to the BH, even though the reprocessed thermal emission (due to disk illumination) remains cold (and thus low) enough to be consistent with the data in contrast to the results of a previous study. The inner reflection component is highly ionized and its fit is primarily driven by its contribution to the continuum, rather than by the shape of the relativistic iron line.<i>Conclusions.<i/> The reprocessed blackbody cannot help determine whether the disk extends close to the BH or not in the hard state. For this specific observation, the flux in inner reflection component turns out to be quite low with respect to the outer reflection or power law. The outflowing slab corona covering the inner region of the disk could be the plausible geometry of the source, with the underlying disk approaching near to the BH.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541807","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 persistent Be enigma: The case of HD 212044","authors":"Alan W. Pereira, Eduardo Janot-Pacheco, Laerte Andrade, Marcelo Emilio","doi":"10.1051/0004-6361/202452215","DOIUrl":"https://doi.org/10.1051/0004-6361/202452215","url":null,"abstract":"We present an analysis of the Be star HD 212044 that reveals intriguing correlations between photometric variations, circumstellar disk emission, and frequencies. Our findings, based on data from the Transiting Exoplanet Survey Satellite (TESS) mission, show an unexpectedly strong negative correlation between photometric brightness and H<i>α<i/> equivalent width, challenging the established understanding of the behavior of Be star seen at low inclination angles. Notably, beating episodes precede brightening events. This study suggests that the variability of HD 212044 may be due to additional mechanisms.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"107 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541758","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 census of the Sun’s ancestors and their contributions to the Solar System chemical composition","authors":"F. Fiore, F. Matteucci, E. Spitoni, M. Molero, P. Salucci, D. Romano, A. Vasini","doi":"10.1051/0004-6361/202451076","DOIUrl":"https://doi.org/10.1051/0004-6361/202451076","url":null,"abstract":"In this work, we compute the rates and numbers of different types of stars and phenomena (supernovae, novae, white dwarfs, merging neutron stars, black holes) that contributed to the chemical composition of the Solar System. During the Big Bang, only light elements formed, while all the heavy ones, from carbon to uranium and beyond, have since been created inside stars. Stars die and release the newly formed elements into the interstellar gas. This process is called ‘chemical evolution’. In particular, we analyse the death rates of stars of all masses, whether they die quiescently or explosively. These rates and total star numbers are computed in the context of a revised version of the two-infall model for the chemical evolution of the Milky Way, which reproduces the observed abundance patterns of several chemical species, the global solar metallicity, and the current gas, stellar, and total surface mass densities relatively well. We also compute the total number of stars ever born and still alive as well as the number of stars born up to the formation of the Solar System with mass and metallicity like those of the Sun. This latter number accounts for all the possible existing Solar systems that can host life in the solar vicinity. We conclude that, among all the stars (from 0.8 to 100 M<sub>⊙<sub/>) that were born and died from the Big Bang up until the Solar System formation epoch and that contributed to its chemical composition, 93.00% were stars that died as single white dwarfs (without interacting significantly with a companion star) and originated in the mass range of 0.8–8 M<sub>⊙<sub/>, while 5.24% were neutron stars and 0.73% were black holes, both originating from core-collapse supernovae (M > 8 M<sub>⊙<sub/>); 0.64% were Type Ia supernovae and 0.40% were nova systems, both originating from the same mass range as the white dwarfs. The number of stars similar to the Sun born from the Big Bang up until the formation of the Solar System, with metallicity in the range 12+log(Fe/H)= 7.50 ± 0.04 dex, is ~31•10<sup>7<sup/>, and in particular our Sun is the ~2.61• 10<sup>7<sup/>-th star of this kind.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541761","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":"Deciphering the JWST spectrum of a ‘little red dot’ at z ∼ 4.53: An obscured AGN and its star-forming host","authors":"Meghana Killi, Darach Watson, Gabriel Brammer, Conor McPartland, Jacqueline Antwi-Danso, Rosa Newshore, Dan Coe, Natalie Allen, Johan P. U. Fynbo, Katriona Gould, Kasper E. Heintz, Vadim Rusakov, Simone Vejlgaard","doi":"10.1051/0004-6361/202348857","DOIUrl":"https://doi.org/10.1051/0004-6361/202348857","url":null,"abstract":"JWST has revealed a class of numerous, extremely compact sources with rest-frame red optical/near-infrared (NIR) and blue ultraviolet (UV) colours nicknamed ‘little red dots’. We present one of the highest signal-to-noise ratio JWST NIRSpec prism spectra of a little red dot, J0647_1045 at <i>z<i/> = 4.5319 ± 0.0001, and examine its NIRCam morphology to differentiate the origin of the UV and optical/NIR emission and elucidate the nature of the little red dot phenomenon. J0647_1045 is unresolved (<i>r<i/><sub>e<sub/> ≲ 0.17 kpc) in the three NIRCam long-wavelength filters but significantly extended (<i>r<i/><sub>e<sub/> = 0.45 ± 0.06 kpc) in the three short-wavelength filters, indicating a red compact source in a blue star-forming galaxy. The spectral continuum shows a clear change in slope, from blue in the optical/UV to red in the rest-frame optical/NIR, which is consistent with two distinct components fit by power laws with different attenuations: <i>A<i/><sub><i>V<i/><sub/> = 0.38 ± 0.01 (UV) and <i>A<i/><sub><i>V<i/><sub/> = 5.61 ± 0.04 (optical/NIR). Fitting the H<i>α<i/> line requires both broad (full width at half maximum of ∼4300 ± 100 km s<sup>−1<sup/>) and narrow components, but none of the other emission lines, including H<i>β<i/>, show evidence of broadness. We calculated <i>A<i/><sub><i>V<i/><sub/> = 0.9 ± 0.4 from the Balmer decrement using narrow H<i>α<i/> and H<i>β<i/> and <i>A<i/><sub><i>V<i/><sub/> > 4.1 ± 0.1 from broad H<i>α<i/> and an upper limit on broad H<i>β<i/>, which is consistent with blue and red continuum attenuation, respectively. Based on a single-epoch H<i>α<i/> line width, the mass of the central black hole is 8 M<sub>⊙<sub/>. Our findings are consistent with a multi-component model, in which the optical/NIR and broad lines arise from a highly obscured, spatially unresolved region, likely a relatively massive active galactic nucleus, while the less obscured UV continuum and narrow lines arise, at least partly, from a small but spatially resolved star-forming host galaxy.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"9 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519514","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}