The Astronomy and Astrophysics Review最新文献

{"title":"An internal heating mechanism operating in ultra-short-period planets orbiting magnetically active stars","authors":"Antonino Francesco Lanza","doi":"10.1051/0004-6361/202140284","DOIUrl":"https://doi.org/10.1051/0004-6361/202140284","url":null,"abstract":"A new mechanism for the internal heating of ultra-short-period planets is proposed based on the gravitational perturbation by a non-axisymmetric quadrupole moment of their host stars. Such a quadrupole is due to the magnetic flux tubes in the stellar convection zone, unevenly distributed in longitude and persisting for many stellar rotations as observed in young late-type stars. The rotation period of the host star evolves from its shortest value on the zero-age main sequence to longer periods due to the loss of angular momentum through a magnetized wind. If the stellar rotation period comes close to twice the orbital period of the planet, the quadrupole leads to a spin-orbit resonance that excites oscillations of the star-planet separation. As a consequence, a strong tidal dissipation is produced inside the planet. We illustrate the operation of the mechanism by modeling the evolution of the stellar rotation and of the innermost planetary orbit in the cases of CoRoT-7, Kepler-78, and K2-141 whose present orbital periods range between 0.28 and 0.85 days. If the spin-orbit resonance occurs, the maximum power dissipated inside the planets ranges between $10^{18}$ and $10^{19}$ W, while the total dissipated energy is of the order of $10^{30}-10^{32}$ J over a time interval as short as $(1-4.5) times 10^{4}$ yr. Such a huge heating over a so short time interval produces a complete melting of the planetary interiors and may shut off their hydromagnetic dynamos. These may initiate a successive phase of intense internal heating owing to unipolar magnetic star-planet interactions and affect the composition and the escape of their atmospheres, producing effects that could be observable during the entire lifetime of the planets [abridged abstract].","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"84 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73112959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Polarised emission from aligned dust grains in nearby galaxies: Predictions from the Auriga simulations","authors":"B. Vandenbroucke, M. Baes, P. Camps, A. U. Kapoor, D. Barrientos, J. Bernard","doi":"10.1051/0004-6361/202141333","DOIUrl":"https://doi.org/10.1051/0004-6361/202141333","url":null,"abstract":"(Aims) In this work, we predict the far-infrared polarisation signal emitted by non-spherical dust grains in nearby galaxies. We determine the angular resolution and sensitivity required to study the magnetic field configuration in these galaxies. (Methods) We post-process a set of Milky Way like galaxies from the Auriga project, assuming a dust mix consisting of spheroidal dust grains that are partially aligned with the model magnetic field. We constrain our dust model using Planck 353 GHz observations of the Milky Way. This model is then extrapolated to shorter wavelengths that cover the peak of interstellar dust emission and to observations of arbitrarily oriented nearby Milky Way like galaxies. (Results) Assuming an intrinsic linear polarisation fraction that does not vary significantly with wavelength for wavelengths longer than 50 micron, we predict a linear polarisation fraction with a maximum of $10-15%$ and a median value of $approx{}7%$ for face-on galaxies and $approx{}3%$ for edge-on galaxies. The polarisation fraction anti-correlates with the line of sight density and with the angular dispersion function which expresses the large scale order of the magnetic field perpendicular to the line of sight. The maximum linear polarisation fraction agrees well with the intrinsic properties of the dust model. The true magnetic field orientation can be traced along low density lines of sight when it is coherent along the line of sight. These results also hold for nearby galaxies, where a coherent magnetic field structure is recovered over a range of different broad bands. (Conclusions) Polarised emission from non-spherical dust grains accurately traces the large scale structure of the galactic magnetic field in Milky Way like galaxies, with expected maximum linear polarisation fractions of $10-15%$. To resolve this maximum, a spatial resolution of at least 1 kpc is required.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"13 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78187314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Structured velocity field in the inner envelope of B335: ALMA observations of rare CO isotopologues","authors":"V. Cabedo, A. Maury, J. Girart, M. Padovani","doi":"10.1051/0004-6361/202140754","DOIUrl":"https://doi.org/10.1051/0004-6361/202140754","url":null,"abstract":"Studying Class 0 objects is very important, as it allows to characterize dynamical processes at the onset of the star formation process, and to determine the physical mechanisms responsible for the outcome of the collapse. Observations of dense gas tracers allow the characterization of key kinematics of the gas directly involved in the star-formation process, such as infall, outflow or rotation. This work aims at investigating the molecular line velocity profiles of the Class 0 protostellar object B335 and attempts to put constraints on the infall motions happening in the circumstellar gas of the object.} Observations of C$^{17}$O (1-0), C$^{18}$O (1-0) and $^{12}CO$ (2-1) transitions are presented and the spectral profiles are analyzed at envelope radii between 100 and 860 au. C$^{17}$O emission presents a double peaked line profile distributed in a complex velocity field. Both peaks present an offset of 0.2 to 1 km s$^{-1}$ from the systemic velocity of the source in the probed area. The optical depth of the C$^{17}$O emission has been estimated and found to be less than 1, suggesting that the two velocity peaks trace two distinct velocity components of the gas in the inner envelope. After discarding possible motions that could produce the complex velocity pattern, such as rotation and outflow, it is concluded that infall is producing the velocity field. Because inside-out symmetric collapse cannot explain those observed profiles, it is suggested that those are produced by non-isotropic accretion from the envelope into the central source along the outflow cavity walls.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"6 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74268008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Fast simulations of extragalactic microlensing","authors":"V. Shalyapin, R. Gil-Merino, L. Goicoechea","doi":"10.1051/0004-6361/202140527","DOIUrl":"https://doi.org/10.1051/0004-6361/202140527","url":null,"abstract":"We present a new and very fast method for producing microlensing magnification maps at high optical depths. It is based on the combination of two approaches: (a) the two-dimensional Poisson solver for a deflection potential and (b) inverse polygon mapping. With our method we extremely reduce the computing time for the generation of magnification patterns and avoid the use of highly demanding computer resources. For example, the generation of a magnification map of size 2000 x 2000 pixels, covering a region of 20 Einstein radii, takes a few seconds on a state-of-the-art laptop. The method presented here will facilitate the massive production of magnification maps for extragalactic microlensing studies within the forthcoming surveys without the need for large computer clusters. The modest demand of computer power and a fast execution time allow the code developed here to be placed on a standard server and thus provide the public online access through a web-based interface.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"23 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73742145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Plasma densitites, flow and Solar EUV flux at comet 67P : A cross-calibration approach","authors":"F. L. Johansson, A. Eriksson, E. Vigren, L. Bucciantini, P. Henri, H. Nilsson, S. Bergman, N. Edberg, G. S. Wieser, E. Odelstad","doi":"10.1051/0004-6361/202039959","DOIUrl":"https://doi.org/10.1051/0004-6361/202039959","url":null,"abstract":"Context.During its two year mission at comet 67P, Rosetta nearly continuously monitored the inner coma plasma environment forgas production rates varying over three orders of magnitude, at distance ...","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"21 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85712207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-frequency characterisation of remnant radio galaxies in the Lockman Hole field","authors":"N. Jurlin, M. Brienza, R. Morganti, Y. Wadadekar, C. Ishwara-Chandra, N. Maddox, V. Mahatma","doi":"10.1051/0004-6361/202040102","DOIUrl":"https://doi.org/10.1051/0004-6361/202040102","url":null,"abstract":"Remnant radio galaxies represent an important phase in the life-cycle of radio active galactic nuclei. It is suggested that in this phase, the jets have switched off and the extended emission is fading rapidly. This phase is not well-studied due to the lack of statistical samples observed at both low and high frequencies. In this work, we study a sample of 23 candidate remnant radio galaxies previously selected using the Low Frequency Array at 150 MHz in the Lockman Hole field. We examine their morphologies and study their spectral properties to confirm their remnant nature and revise the morphological and spectral criteria used to define the initial sample. We present new observations with the Karl G. Jansky Very Large Array at 6000 MHz at both high and low resolution. These observations allowed us to observe the presence or absence of cores and study the spectral curvature and steepness of the spectra of the total emission expected at these high frequencies for the remnant candidates. We confirm 13 out of 23 candidates as remnant radio sources. This corresponds to 7% of the full sample of active, restarted, and remnant candidates from the Lockman Hole field. Surprisingly, only a minority of remnants reside in a cluster (23%). The remnant radio galaxies show a range of properties and morphologies. The majority do not show detection of the core at 6000 MHz and their extended emission often shows ultra-steep spectra (USS). However, there are also remnants with USS total emission and a detection of the core at 6000 MHz, possibly indicating a variety of evolutionary stages in the remnant phase. We confirm the importance of the combination of morphological and spectral criteria and this needs to be taken into consideration when selecting a sample of remnant radio sources.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"5 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87588801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Polarimetric signature of ocean as detected by near-infrared Earthshine observations","authors":"J. Takahashi, Y. Itoh, T. Matsuo, Y. Oasa, Y. P. Bach, M. Ishiguro","doi":"10.1051/0004-6361/202039331","DOIUrl":"https://doi.org/10.1051/0004-6361/202039331","url":null,"abstract":"Context. The discovery of an extrasolar planet with an ocean has crucial importance in the search for life beyond Earth. The polari- metric detection of specularly reflected light from a smooth liquid surface is anticipated theoretically, though the polarimetric signature of Earth’s oceans has not yet been conclusively detected in disk-integrated planetary light. Aims. We aim to detect and measure the polarimetric signature of the Earth’s oceans. Methods. We conducted near-infrared polarimetry for lunar Earthshine and collected data on 32 nights with a variety of ocean frac- tions in the Earthshine-contributing region. Results. A clear positive correlation was revealed between the polarization degree and ocean fraction. We found hourly variations in polarization in accordance with rotational transition of the ocean fraction. The ratios of the variation to the typical polarization degree were as large as ∼ 0.2–1.4. Conclusions. Our observations provide plausible evidence of the polarimetric signature attributed to Earth’s oceans. Near-infrared polarimetry may be considered a prospective technique in the search for exoplanetary oceans.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"24 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88577288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Local alignments of parsec-scale AGN radiojets","authors":"N. Mandarakas, D. Blinov, C. Casadio, V. Pelgrims, S. Kiehlmann, V. Pavlidou, K. Tassis","doi":"10.1051/0004-6361/202140764","DOIUrl":"https://doi.org/10.1051/0004-6361/202140764","url":null,"abstract":"Context.Coherence in the characteristics of neighboring sources in 2D and 3D space may suggest the existence of large-scale cosmic structures, which are useful for cosmological studies. Numerous works have been conducted to detect such features in global scalesas well as in confined areas of the sky. However, results are often contradictory and their interpretation remains controversial. Aims.We investigate the potential alignment of parsec-scale radio jets in localized regions of the coordinates-redshift space. Methods.We use data from the Astrogeo VLBI FITS image database to deduce jet directions of radio sources. We perform the search for statistical alignments between nearby sources and explore the impact of instrumental biases. Results.We unveil four regions for which the alignment between jet directions deviates from randomness at a significance level of more than 5 sigma and is unlikely due to instrumental systematics. Intriguingly, their locations coincide with other known large-scale cosmic structures and/or regions of alignments. Conclusions.If the alignments found are the result of physical processes, the discovered regions may designate some of the largest structures known to date.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"115 11 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90231262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Relation of internal attenuation, dust emission, and the size of spiral galaxies","authors":"M. L. Corredoira, C. Gutiérrez","doi":"10.1051/0004-6361/202140851","DOIUrl":"https://doi.org/10.1051/0004-6361/202140851","url":null,"abstract":"Aims. Dust in spiral galaxies produces emission in the far-infrared (FIR) and internal absorption in visible wavelengths. However, the relation of the two amounts is not trivial because optical absorption may saturate, but the FIR emission does not. Moreover, the volume concentration of dust plays a role in the relation of absorption and emission, which depends on the size of the galaxy. We explore the relation of these three quantities. Methods. In order to understand the geometrical problem, we developed a model of dust distribution. We also investigated the relation of the three variables with real data of spiral galaxies at z < 0.2 using the spectroscopic Sloan Digital Sky Survey (SDSS) and FIR AKARI survey. Internal absorptions were derived with two different methods: the ratio of emission lines Hα and Hβ, and a previously calibrated relation based on the color variations as a function of absolute magnitude and concentration index. Results. We find that in our low-z sample, the dependence of the average internal attenuation on galaxy size is negligible on average because of the relation of dust mass with size. It allows us to derive the internal attenuation of the galaxy, AV , even when we only know its FIR flux. This attenuation approximately depends on the inclination of the galaxy i as AV = γV log10 ( 1 cos i ) , where γV is a constant. We found that γV has a maximum value for galaxies of 1.45 ± 0.27 magnitudes. When similar properties of dust are assumed, a general expression can be used at any z: γV = (1.45 ± 0.27) f exp [−(1.0±0.6) fM ] M and fM = 7.6×10−6α−1.75 hR × ( FFIR 700 Jy )1.87 × fcosmol.(z); the dependence on the cosmological model is embedded in fcosmol.(z) = dL(z)(Mpc)(1+ z)(1.75η−1.87), where η = 2 for cosmologies following Etherington’s relation, dL is the luminosity distance, αhR is the angular size of the scalelength, and FFIR the flux at wavelength 100(1 + z) μm. Conclusions. For cases of nonsaturation ( f . 3.6), this might be used as a cosmological test because the factor fcosmol. at high z varies strongly in different cosmologies. Although the present-day sensitivity of FIR or millimeter surveys does not allow us to carry out this cosmological test within the standard model, it may be used in the future, when we can observe galaxies at z = 3− 5 with a sensitivity at ∼500 μm better than ∼ 10 μJy, for instance. For much lower z or different cosmological models, a test might be feasible at present.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"138 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79818127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 rho Ophiuchi region revisited with Gaia EDR3. Two young populations, new members, and old impostors","authors":"Natalie Grasser, Sebastian Ratzenböck, J. Alves, J. Großschedl, S. Meingast, C. Zucker, Á. Hacar, C. Lada, A. Goodman, M. Lombardi, John C. Forbes, I. Bomze, Torsten Möller","doi":"10.1051/0004-6361/202140438","DOIUrl":"https://doi.org/10.1051/0004-6361/202140438","url":null,"abstract":"Context. Young and embedded stellar populations are important probes of the star formation process. Their properties and the environments they create have the potential to a ff ect the formation of new planets. Paradoxically, we have a better census of nearby embedded young populations than of the slightly more evolved optically visible young populations. The high accuracy measurements and all-sky coverage of Gaia data are about to change this situation. Aims. This work aims to construct the most complete sample to date of young stellar objects (YSOs) in the ρ Oph region. Methods. We compile a catalog of 1114 Ophiuchus YSOs from the literature and cross-match it with the Gaia EDR3, Gaia -ESO, and APOGEE-2 surveys. We apply a multivariate classification algorithm to this catalog to identify new, co-moving population candidates. Results. We find 191 new high-fidelity YSO candidates in the Gaia EDR3 catalog belonging to the ρ Oph region. The new sources appear to be mainly ClassIII M stars and substellar objects and are less extincted than the known members, while we find that 28 of the previously unknown sources are YSOs with circumstellar disks (ClassI or ClassII). The analysis of the proper motion distri- bution of the entire sample reveals a well-defined bimodality, implying two distinct populations sharing a similar 3D volume. The first population comprises young stars’ clusters around the ρ Ophiuchi star and the main Ophiuchus clouds (L1688, L1689, L1709). In contrast, the second population is slightly older ( ∼ 10Myr), more dispersed, has a distinct proper motion, and is possibly from the Upper Sco group. The two populations are moving away from each other at about 4.1kms − 1 and will no longer overlap in about 4Myr. Finally, we flag 17 sources in the literature sample as likely impostors, which are sources that exhibit large deviations from the average properties of the ρ Oph population. Our results show the importance of accurate 3D space and motion information for improved stellar population analysis.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"72 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89522995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}