Proyecto de Investigación: ESP2017-87676-C5-1-R
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ESP2017-87676-C5-1-R
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A precise architecture characterization of the π Mensae planetary system
(EDP Sciences, 2020-10-01) Damasso, D.; Sozzetti, A; Lovis, C.; Barros, S. C. C.; Sousa, S. G.; Demangeon, O. D. S.; Faria, J. P.; Lillo Box, J.; Cristiani, S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Zapatero Osorio, M. R.; Amate, M.; Pasquini, L.; Zerbi, Filippo M.; Adibekyan, V.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Álvarez, D.; Alves, D.; Ávila, G.; Baldini, V.; Bandy, T.; Benz, W.; Bianco, A.; Borsa, F.; Bossini, D.; Bourrier, V.; Bouchy, F.; Broeg, C.; Cabral, A.; Calderone, G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.; Cupani, G.; D´Odorico, V.; Deiries, S.; Dekker, H.; Delabre, B.; Di Marcoantonio, P.; Dumusque, X.; Ehrenreich, D.; Figueira, P.; Fragoso, A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Hughes, I.; Iwert, O.; Kerber, F.; Knudstrup, J.; Landoni, M.; Lavie, B.; Lizon, J. L.; Lo Curto, G.; Maire, C.; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro, M. J. P. F. G.; Moschetti, M.; Mueller, E.; Murphy, M. T.; Nunes, N.; Oggioni, L.; Oliveira, A.; Oshagh, M.; Pallé, E.; Pariani, G.; Poretti, E.; Rasilla, J. L.; Rebordao, J.; Redaelli, E.; Riva, M.; Santa Tschudi, S.; Santin, P.; Santos, P.; Ségransan, D.; Schmidt, T. M.; Segovia, A.; Sosnowska, D.; Spanò, P.; Suárez Mascareño, A.; Tabernero, H.; Tenegi, F.; Udry, S.; Zanutta, A.; González Hernández, Carmen; Swiss National Science Foundation (SNSF); Agenzia Spaziale Italiana (ASI); Fundação para a Ciência e a Tecnologia (FCT); Australian Research Council (ARC); Istituto Nazionale Astrofisica (INAF); 0000-0003-0987-1593; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The bright star pi Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern Observatory's Very Large Telescope. The star hosts a multi-planet system (a transiting 4 M-circle plus planet at similar to 0.07 au and a sub-stellar companion on a similar to 2100-day eccentric orbit), which is particularly suitable for a precise multi-technique characterization.
Aims. With the new ESPRESSO observations, which cover a time span of 200 days, we aim to improve the precision and accuracy of the planet parameters and search for additional low-mass companions. We also take advantage of the new photometric transits of pi Men c observed by TESS over a time span that overlaps with that of the ESPRESSO follow-up campaign.
Methods. We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We further characterized the system by means of absolute astrometry with HIPPARCOS and Gaia. We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters.
Results. We present a precise characterization of the planetary system around pi Men. The ESPRESSO radial velocities alone (37 nightly binned data with typical uncertainty of 10 cm s(-1)) allow for a precise retrieval of the Doppler signal induced by pi Men c. The residuals show a root mean square of 1.2 m s(-1), which is half that of the HARPS data; based on the residuals, we put limits on the presence of additional low-mass planets (e.g. we can exclude companions with a minimum mass less than similar to 2 M-circle plus within the orbit of pi Men c). We improve the ephemeris of pi Men c using 18 additional TESS transits, and, in combination with the astrometric measurements, we determine the inclination of the orbital plane of pi Men b with high precision (i(b) =45.8(-1.1)(+1.4) deg). This leads to precise measurement of its absolute mass m(b) = =14.1(-0.4)(+0.5) M-Jup, indicating that pi Men b can be classified as a brown dwarf.
Conclusions. The pi Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. Our determination of the 3D architecture of the pi Men planetary system and the high relative misalignment of the planetary orbital planes put constraints on and challenge the theories of the formation and dynamical evolution of planetary systems. The accurate measurement of the mass of pi Men b contributes to make the brown dwarf desert a bit greener.
The IACOB project VI. On the elusive detection of massive O-type stars close to the ZAMS
(EDP Sciences, 2020-06-30) Holgado, G.; Simón Díaz, S.; Haemmerlé, L.; Lennon, D. J.; Barbá, R. H.; Cerviño, M.; Castro, N.; Herrero, A.; Meynet, G.; Arias, J. I.; Agencia Estatal de Investigación (AEI); Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI); Swiss National Science Foundation (SNSF); European Research Council (ERC); Holgado, G. [0000-0002-9296-8259]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The apparent lack of massive O-type stars near the zero-age main sequence, or ZAMS (at ages <2 Myr), is a topic that has been widely discussed in the past 40 yr. Different explanations for the elusive detection of these young massive stars have been proposed from the observational and theoretical side, but no firm conclusions have been reached yet.
Aims. We reassess this empirical result here, benefiting from the high-quality spectroscopic observations of (more than 400) Galactic O-type stars gathered by the IACOB and OWN surveys.
Methods. We used effective temperatures and surface gravities resulting from a homogeneous semi-automatized IACOB-GBAT/FASTWIND spectroscopic analysis to locate our sample of stars in the Kiel and spectroscopic Hertzsprung-Russell (sHR) diagrams. We evaluated the completeness of our magnitude-limited sample of stars as well as potential observational biases affecting the compiled sample using information from the Galactic O star catalog. We discuss limitations and possible systematics of our analysis method, and compare our results with other recent studies using smaller samples of Galactic O-type stars. We mainly base our discussion on the distribution of stars in the sHR diagram in order to avoid the use of still uncertain distances to most of the stars in our sample. However, we also performed a more detailed study of the young cluster Trumpler-14 as an illustrative example of how Gaia cluster distances can help to construct the associated classical HR diagram.
Results. We find that the apparent lack of massive O-type stars near the ZAMS with initial evolutionary masses in the range between ≈30 and 70 M⊙ still persist even when spectroscopic results from a large non-biased sample of stars are used. We do not find any correlation between the dearth of stars close to the ZAMS and obvious observational biases, limitations of our analysis method, and/or the use of one example spectroscopic HR diagram instead of the classical HR diagram. Finally, by investigating the effect of the efficiency of mass accretion during the formation process of massive stars, we conclude that an adjustment of the mass accretion rate towards lower values than canonically assumed might reconcile the hotter boundary of the empirical distribution of optically detected O-type stars in the spectroscopic HR diagram and the theoretical birthline for stars with masses above ≈30 M⊙. Last, we also discuss how the presence of a small sample of O2-O3.5 stars found much closer to the ZAMS than the main distribution of Galactic O-type star might be explained in the context of this scenario when the effect of nonstandard star evolution (e.g. binary interaction, mergers, and/or homogeneous evolution) is taken into account.
A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
(Oxford Academics: Oxford University Press, 2021-01-25) Osborn, Hugh P.; Armstrong, D. J.; Adibekyan, V.; Collins, K. A.; Delgado Mena, E.; Howell, Steve B.; Hellier, C.; King, G. W.; Lillo Box, J.; Nielsen, L. D.; Otegi, J. F.; Santos, N. C.; Ziegler, C.; Anderson, D. R.; Briceño, C.; Burke, C. J.; Bayliss, D.; Barrado, D.; Bryant, E. M.; Brown, D. J. A.; Barros, S. C. C.; Bouchy, F.; Caldwell, D. A.; Conti, D.; Díaz, R. F.; Dragomir, D.; Deleuil, M.; Demanegon, O. D. S.; Dorn, C.; Daylan, T.; Figueira, P.; Helled, R.; Hoyer, S.; Jenkins, J. S.; Jensen, E. L. N.; Latham, D. W.; Law, N.; Louie, D.; Mann, A. W.; Osborn, A.; Pollacco, D.; Rodríguez, D. R.; Rackham, B. V.; Ricker, G.; Scott, N. J.; Sousa, S. G.; Seager, S.; Stassun, K. G.; Smith, J. C.; Strom, P.; Udry, S.; Villaseñor, J. N.; Vanderspek, R.; West, R.; Wheatley, P. J.; Winn, J. N.; Fundacao para a Ciencia e a Tecnologia (FCT); Science and Technology Facilities Council (STFC); Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); UK Space Agency; Dorn, C. [0000-0001-6110-4610]; Anderson, D. [0000-0001-7416-7522]; Barros, S. [0000-0003-2434-3625]; Adibekyan, V. [0000-0002-0601-6199]; Armstrong, D. [0000-0002-5080-4117]; Santos, N. [0000-0003-4422-2919]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We report the discovery of HD 110113 b (TESS object of interest-755.01), a transiting mini-Neptune exoplanet on a 2.5-d orbit around the solar-analogue HD 110113 (Teff = 5730 K). Using TESS photometry and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities gathered by the NCORES program, we find that HD 110113 b has a radius of 2.05 ± 0.12 R⊕ and a mass of 4.55 ± 0.62 M⊕. The resulting density of 2.90+0.75−0.59 g cm−3 is significantly lower than would be expected from a pure-rock world; therefore HD 110113 b must be a mini-Neptune with a significant volatile atmosphere. The high incident flux places it within the so-called radius valley; however, HD 110113 b was able to hold on to a substantial (0.1–1 per cent) H–He atmosphere over its ∼4 Gyr lifetime. Through a novel simultaneous Gaussian process fit to multiple activity indicators, we were also able to fit for the strong stellar rotation signal with period 20.8 ± 1.2 d from the RVs and confirm an additional non-transiting planet, HD 110113 c, which has a mass of 10.5 ± 1.2 M⊕ and a period of 6.744+0.008−0.009 d.
MOS spectroscopy of protocluster candidate galaxies at z = 6.5
(Oxford Academics: Oxford University Press, 2019-08-16) Calvi, R.; Rodríguez Espinosa, J. M.; Mas hesse, J. M.; Chanchaiworawit, K.; Guzman, R.; Salvador Solé, E.; Gallego, J.; Herrero, A.; Manrique, Alberto; Marín Franch, A.; National Astronomical Research Institute of Thailand (NARIT); European Commission (EC); Ministry of Education, Culture, Sports, Science and Technology (MEXT); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Manríque, A. [0000-0001-5339-2659]; Gallego, J. [0000-0003-1439-7697]; Calvi, R. [0000-0002-1462-9462]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Instituto de Ciencias del Cosmos (ICCUB), MDM-2014-0369
The epoch corresponding to a redshift of z ∼ 6.5 is close to full re-ionization of the Universe, and early enough to provide an intriguing environment to observe the early stage of large-scale structure formation. It is also an epoch that can be used to verify the abundance of a large population of low luminosity star-forming galaxies that are deemed responsible for cosmic re-ionization. Here, we present the results of follow-up multi-object spectroscopy using OSIRIS at Gran Telescopio Canarias of 16 Ly α emitter (LAE) candidates discovered in the Subaru/XMM Newton Deep Survey. We have securely confirmed 10 LAEs with sufficient signal-to-noise ratio of the Ly α emission line. The inferred star formation rates of the confirmed LAEs are on the low side, within the range 0.9–4.7 M⊙ yr−1. However, they show relatively high Ly α rest frame equivalent widths. Finally we have shown that the mechanical energy released by the star formation episodes in these galaxies is enough to create holes in the neutral hydrogen medium such that Lyman continuum photons can escape to the intergalactic medium, thus contributing to the re-ionization of the Universe.
Searching for correlations in Gaia DR2 unbound star trajectories
(Oxford Academics: Oxford University Press, 2019-11-15) Montanari, F.; Barrado, D.; García Bellido, J.; Agencia Estatal de Investigación (AEI); Barrado, D. [0000-0002-5971-9242]; Montanari, F. [0000-0003-0741-1382]; García Bellido, J. [0000-0002-9370-8360]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE FISICA TEORICA (IFT), SEV-2016-0597
Scattering events with compact objects are expected in the primordial black hole (PBH) cold dark matter (CDM) scenario, due to close encounters between stars and PBHs in the dense environments of dwarf spheroidals. We develop a Bayesian framework to search for correlations among Milky Way stellar trajectories and those of globular clusters and dwarf galaxies in the halo and in other nearby galaxies. We apply the method to a selection of hypervelocity stars (HVS) and globular clusters from the Gaia DR2 catalogue and known nearby (mostly dwarf) galaxies with full phase-space and size measurements. We report positive evidence for trajectory intersection ∼20–40 Myr ago of up to two stars, depending on priors, with the Sagittarius dwarf spheroidal galaxy (dSph) when assuming the distance estimates of Marchetti, Rossi & Brown (2018). We verify that the result is compatible with their evolutionary status, setting a lower bound for their stellar age of ∼100 Myr. However, such scattering events are not confirmed when assuming Anders et al. (2019) distance estimates. We discuss shortcomings related to present data quality and future prospects for detection of HVS with the full Gaia catalogue and Sagittarius dSph.
