Centro de Astrobiología
URI permanente para esta comunidadhttps://inta.metricsalad.com/handle/123456789/6
El Centro de Astrobiología (CAB) es un centro de investigación mixto del Consejo Superior de Investigaciones Científicas (CSIC) y del Instituto Nacional de Técnica Aeroespacial (INTA). Creado en 1999, fue el primer centro del mundo dedicado específicamente a la investigación astrobiológica. En abril del 2000, se convirtió en el primer centro asociado al NASA Astrobiology Institute (NAI).
Su principal objetivo es estudiar el origen, presencia e influencia de la vida en el universo. Se trata de un centro multidisciplinar, que alberga más de 150 técnicos y científicos especialistas en diferentes ramas. Además, cuenta con diferentes unidades de apoyo, como la Unidad de Cultura Científica, la Unidad de Gestión y una extensa biblioteca científica.
Cabe destacar que en el CAB se ha desarrollado el instrumento REMS (Rover Environmental Monitoring Station) para la misión MSL de la NASA; se trata de una estación medioambiental que está a bordo del rover Curiosity, en Marte desde 2012. También se ha desarrollado el instrumento TWINS (Temperature and Wind sensors for INSight) para la misión InSight de la NASA, en Marte desde noviembre de 2018. En la actualidad se está trabajando en el desarrollo del instrumento MEDA (Mars Environtmental and Dynamics Analizar) para la misión Mars 2020 de la NASA; y en RLS (Raman Laser Spectrometer) para la misión de la ESA ExoMars 2020. El CAB también participa en diferentes misiones e instrumentos de gran relevancia astrobiológica tales como CARMENES, CHEOPS, PLATO, el telescopio espacial James Webb (JWST) con los instrumentos MIRI y NIRSPEC y la misión BepiColombo de la ESA al planeta Mercurio.
El CAB ha recibido la distinción como Unidad de Excelencia María de Maeztu en la convocatoria de 2017 del Ministerio de Ciencia, Innovación y Universidades, destinada a reconocer la excelencia en estructuras organizativas de investigación.
Más información en https://cab.inta-csic.es/
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Examinando Centro de Astrobiología por Materia "Accretion disks"
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Publicación Acceso Abierto K-band GRAVITY/VLTI interferometry of “extreme” Herbig Be stars. The size–luminosity relation revisited(EDP Sciences, 2021-08-11) Marcos Arenal, P.; Mendigutía, I.; Koumpia, E.; Oudmaijer, R. D.; Vioque, M.; Guzmán Díaz, J.; Wichittanakom, C.; De Wit, W. J.; Montesinos, B.; Ilee, J. D.; Agencia Estatal de Investigación (AEI), European Research Council; Comunidad de Madrid; Science and Technology Facilities Council (STFC); European Research Council (ERC); Marcos Arenal, P. [0000-0003-1549-9396]Context. It has been hypothesized that the location of Herbig Ae/Be stars (HAeBes) within the empirical relation between the inner disk radius (rin), inferred from K-band interferometry, and the stellar luminosity (L*), is related to the presence of the innermost gas, the disk-to-star accretion mechanism, the dust disk properties inferred from the spectral energy distributions (SEDs), or a combination of these effects. However, no general observational confirmation has been provided to date. Aims. This work aims to test whether the previously proposed hypotheses do, in fact, serve as a general explanation for the distribution of HAeBes in the size–luminosity diagram. Methods. GRAVITY/VLTI spectro-interferometric observations at ~2.2 μm have been obtained for five HBes representing two extreme cases concerning the presence of innermost gas and accretion modes. V590 Mon, PDS 281, and HD 94509 show no excess in the near-ultraviolet, Balmer region of the spectra (ΔDB), indicative of a negligible amount of inner gas and disk-to-star accretion, whereas DG Cir and HD 141926 show such strong ΔDB values that cannot be reproduced from magnetospheric accretion, but probably come from the alternative boundary layer mechanism. In turn, the sample includes three Group I and two Group II stars based on the Meeus et al. SED classification scheme. Additional data for these and all HAeBes resolved through K-band interferometry have been compiled from the literature and updated using Gaia EDR3 distances, almost doubling previous samples used to analyze the size–luminosity relation. Results. We find no general trend linking the presence of gas inside the dust destruction radius or the accretion mechanism with the location of HAeBes in the size–luminosity diagram. Similarly, our data do not support the more recent hypothesis linking such a location and the SED groups. Underlying trends are present and must be taken into account when interpreting the size–luminosity correlation. In particular, it cannot be statistically ruled out that this correlation is affected by dependencies of both L* and rin on the wide range of distances to the sources. Still, it is argued that the size–luminosity correlation is most likely to be physically relevant in spite of the previous statistical warning concerning dependencies on distance. Conclusions. Different observational approaches have been used to test the main scenarios proposed to explain the scatter of locations of HAeBes in the size–luminosity diagram. However, none of these scenarios have been confirmed as a fitting general explanation and this issue remains an open question.Publicación Acceso Abierto On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer?(Multidisciplinary Digital Publishing Institute (MDPI), 2020-05-05) Mendigutía, I.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Mendigutía, I. [0000-0002-0233-5328]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Understanding how young stars gain their masses through disk-to-star accretion is of paramount importance in astrophysics. It affects our knowledge about the early stellar evolution, the disk lifetime and dissipation processes, the way the planets form on the smallest scales, or the connection to macroscopic parameters characterizing star-forming regions on the largest ones, among others. In turn, mass accretion rate estimates depend on the accretion paradigm assumed. For low-mass T Tauri stars with strong magnetic fields there is consensus that magnetospheric accretion (MA) is the driving mechanism, but the transfer of mass in massive young stellar objects with weak or negligible magnetic fields probably occurs directly from the disk to the star through a hot boundary layer (BL). The intermediate-mass Herbig Ae/Be (HAeBe) stars bridge the gap between both previous regimes and are still optically visible during the pre-main sequence phase, thus constituting a unique opportunity to test a possible change of accretion mode from MA to BL. This review deals with our estimates of accretion rates in HAeBes, critically discussing the different accretion paradigms. It shows that although mounting evidence supports that MA may extend to late-type HAes but not to early-type HBes, there is not yet a consensus on the validity of this scenario versus the BL one. Based on MA and BL shock modeling, it is argued that the ultraviolet regime could significantly contribute in the future to discriminating between these competing accretion scenarios.Publicación Acceso Abierto Rapid late-time X-ray brightening of the tidal disruption event OGLE16aaa(EDP Sciences, 2020-07-16) Kajava, J. J. E.; Giustini, M.; Saxton, R. D.; Miniutti, G.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Kajava, J. J. E. [0000-0002-3010-8333]; Giustini, M. [0000-0002-1329-658X]; Unidad de Excelencia Científica María de Maeztu del Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Stars that pass too close to a super-massive black hole may be disrupted by strong tidal forces. OGLE16aaa is one such tidal disruption event (TDE) which rapidly brightened and peaked in the optical/UV bands in early 2016 and subsequently decayed over the rest of the year. OGLE16aaa was detected in an XMM-Newton X-ray observation on June 9, 2016 with a flux slightly below the Swift/XRT upper limits obtained during the optical light curve peak. Between June 16–21, 2016, Swift/XRT also detected OGLE16aaa and based on the stacked spectrum, we could infer that the X-ray luminosity had jumped up by more than a factor of ten in just one week. No brightening signal was seen in the simultaneous optical/UV data to cause the X-ray luminosity to exceed the optical/UV one. A further XMM-Newton observation on November 30, 2016 showed that almost a year after the optical/UV peak, the X-ray emission was still at an elevated level, while the optical/UV flux decay had already leveled off to values comparable to those of the host galaxy. In all X-ray observations, the spectra were nicely modeled with a 50–70 eV thermal component with no intrinsic absorption, with a weak X-ray tail seen only in the November 30 XMM-Newton observation. The late-time X-ray behavior of OGLE16aaa strongly resembles the tidal disruption events ASASSN-15oi and AT2019azh. We were able to pinpoint the time delay between the initial optical TDE onset and the X-ray brightening to 182 ± 5 days, which may possibly represent the timescale between the initial circularization of the disrupted star around the super-massive black hole and the subsequent delayed accretion. Alternatively, the delayed X-ray brightening could be related to a rapid clearing of a thick envelope that covers the central X-ray engine during the first six months.Publicación Acceso Abierto Rapid spectral transition of the black hole binary V404 Cygni(EDP Sciences, 2020-02-13) Kajava, J. J. E.; Sánchez Fernández, C.; Alfonso Garzón, J.; Motta, Sara E.; Veledina, A.; Science and Technology Facilities Council (STFC); Academy of Finland (AKA); Agencia Estatal de Investigación (AEI); Ministry of Education and Science of the Russian Federation (Minobrnauka); Kajava, J. J. E. [0000-0002-3010-8333]; Alfonso Garzón, J. [0000-0003-0852-3474]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737During the June 2015 outburst of the black hole binary V404 Cyg, rapid changes in the X-ray brightness and spectra were common. The INTEGRAL monitoring campaign detected spectacular Eddington-limited X-ray flares, but also rapid variations at much lower flux levels. On 2015 June 21 at 20 h 50 min, the 3–10 keV JEM-X data as well as simultaneous optical data started to display a gradual brightening from one of these low-flux states. This was followed 15 min later by an order-of-magnitude increase of flux in the 20–40 keV IBIS/ISGRI light curve in just 15 s. The best-fitting model for both the pre- and post-transition spectra required a Compton-thick partially covering absorber. The absorber parameters remained constant, but the spectral slope varied significantly during the event, with the photon index decreasing from Γ ≈ 3.7 to Γ ≈ 2.3. We propose that the rapid 20–40 keV flux increase was either caused by a spectral state transition that was hidden from our direct view, or that there was a sudden reduction in the amount of Compton down-scattering of the primary X-ray emission in the disk outflow.Publicación Acceso Abierto The Gaia-ESO Survey: Age spread in the star forming region NGC 6530 from the HR diagram and gravity indicators(EDP Sciences, 2019-03-26) Prisinzano, L.; Damiani, F.; Kalari, V.; Jeffries, R. D.; Bonito, R.; Micela, G.; Wright, N. James; Jackson, R. J.; Tognelli, E.; Guarcello, M. G.; Vink, Jorick S.; Klutsch, A.; Jiménez Esteban, F. M.; Roccatagliata, V.; Tautvaisilenè, G.; Gilmore, G.; Randich, S.; Alfaro, Emilio J.; Flaccomio, E.; Koposov, S.; Lanzafame, A. C.; Pancino, E.; Bergemann, M.; Carraro, G.; Franciosini, E.; Frasca, A.; Gonneau, A.; Hourihane, A.; Jofre, P.; Lewis, J.; Magrini, L.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Worley, Charlotte C.; Zaggia, S.; European Commission (EC); Leverhulme Trust; Istituto Nazionale di Astrofisica (INAF); Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Context. In very young clusters, stellar age distribution is empirical proof of the duration of star cluster formation and thus it gives indications of the physical mechanisms involved in the star formation process. Determining the amount of interstellar extinction and the correct reddening law are crucial steps to derive fundamental stellar parameters and in particular accurate ages from the Hertzsprung-Russell diagram. Aims. In this context, we seek to derive accurate stellar ages for NGC 6530, the young cluster associated with the Lagoon Nebula to infer the star formation history of this region. Methods. We used the Gaia-ESO survey observations of the Lagoon Nebula, together with photometric literature data and Gaia DR2 kinematics, to derive cluster membership and fundamental stellar parameters. Using spectroscopic effective temperatures, we analysed the reddening properties of all objects and derived accurate stellar ages for cluster members. Results. We identified 652 confirmed and 9 probable members. The reddening inferred for members and non-members allows us to distinguish foreground objects, mainly main-sequence stars, and background objects, mainly giants, and to trace the three-dimensional structure of the nebula. This classification is in agreement with the distances inferred from Gaia DR2 parallaxes for these objects. Finally, we derive stellar ages for 382 confirmed cluster members for which we obtained the individual reddening values. In addition, we find that the gravity-sensitive γ index distribution for the M-type stars is correlated with stellar age. Conclusions. For all members with Teff < 5500 K, the mean logarithmic age is 5.84 (units of years) with a dispersion of 0.36 dex. The age distribution of stars with accretion or discs, i.e. classical T Tauri stars with excess (CTTSe), is similar to that of stars without accretion and without discs, i.e. weak T Tauri stars with photospheric emission (WTTSp). We interpret this dispersion as evidence of a real age spread since the total uncertainties on age determinations, derived from Monte Carlo simulations, are significantly smaller than the observed spread. This conclusion is supported by evidence of the decrease of the gravity-sensitive γ index as a function of stellar ages. The presence of a small age spread is also supported by the spatial distribution and kinematics of old and young members. In particular, members with accretion or discs, formed in the last 1 Myr, show evidence of subclustering around the cluster centre, in the Hourglass Nebula and in the M8-E region, suggesting a possible triggering of star formation events by the O-type star ionization fronts.Publicación Acceso Abierto The widest Hα survey of accreting protoplanets around nearby transition disks(EDP Sciences, 2020-01-21) Zurlo, A.; Cugno, G.; Montesinos, M.; Canovas, H.; Casassus, S.; Christiaens, V.; Cieza, L.; Huélamo, N.; Pérez Barrio, Sandra; Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Swiss National Science Foundation (SNSF); Agencia Estatal de Investigación (AEI); The Chinese Academy of Science South America Center for Astronomy (CASSACA); Huelamo, N. [0000-0002-2711-8143]; Pérez, S. [0000-0003-2953-755X]; Zurlo, A. [0000-0002-5903-8316]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Context. The mechanisms of planet formation are still under debate. We know little about how planets form, even if more than 4000 exoplanets have been detected to date. Recent investigations target the cot of newly born planets: the protoplanetary disk. At the first stages of their life, exoplanets still accrete material from the gas-rich disk in which they are embedded. Transitional disks are indeed disks that show peculiarities, such as gaps, spiral arms, and rings, which can be connected to the presence of substellar companions. Aims. To investigate what is responsible for these features, we selected all the known transitional disks in the solar neighborhood (<200 pc) that are visible from the southern hemisphere. We conducted a survey of 11 transitional disks with the SPHERE instrument at the Very Large Telescope. This is the largest Hα survey that has been conducted so far to look for protoplanets. The observations were performed with the Hα filter of ZIMPOL in order to target protoplanets that are still in the accretion stage. All the selected targets are very young stars, less than 20 Myr, and show low extinction in the visible. Methods. We reduced the ZIMPOL pupil stabilized data by applying the method of the angular spectral differential imaging (ASDI), which combines both techniques. The datacubes are composed of the Cnt_Hα and the narrow band filter Hα, which are taken simultaneously to permit the suppression of the speckle pattern. The principal component analysis method was employed for the reduction of the data. For each dataset, we derived the 5σ contrast limit and converted it in upper limits on the accretion luminosity. Results. We do not detect any new accreting substellar companions around the targeted transition disks down to an average contrast of 12 magnitudes at 0.′′2 from the central star. We have recovered the signal of the accreting M star companion around the star HD 142527. We have detected and resolved, for the first time in visible light, the quadruple system HD 98800. For every other system, we can exclude the presence of massive actively accreting companions, assuming that the accretion is not episodic and that the extinction is negligible. The mean accretion luminosity limit is 10−6 L⊙ at a separation of 0.′′2 from the host.
