Proyecto de Investigación: EL SURGIMIENTO DE LA SIMETRIA AXIAL EN NEBULOSAS DE ESTRELLAS EVOLUCIONADAS
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AYA2016-78994-P
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The post-common-envelope binary central star of the planetary nebula ETHOS 1
(Oxford Academics: Oxford University Press, 2020-09-11) Munday, J.; Jones, David; García Rojas, J.; Boffin, H. M. J.; Miszalski, B.; Corradi, R. L. M.; Rodríguez Gil, P.; Rubio Díez, M. M.; Santander García, M.; Sowicka, P.; National Science Centre, Poland (NCN); Agencia Estatal de Investigación (AEI); 0000-0002-1872-5398; 0000-0003-3947-5946; 0000-0002-6138-1869; 0000-0002-9486-4840; 0000-0003-2561-6306; 0000-0002-6605-0268; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present a detailed study of the binary central star of the planetary nebula ETHOS 1 (PN G068.1+11.0). Simultaneous modelling of light and radial velocity curves reveals the binary to comprise a hot and massive pre-white dwarf with an M-type main-sequence companion. A good fit to the observations was found with a companion that follows expected mass–temperature–radius relationships for low-mass stars, indicating that despite being highly irradiated, it is consistent with not being significantly hotter or larger than a typical star of the same mass. Previous modelling indicated that ETHOS 1 may comprise the first case where the orbital plane of the central binary does not lie perpendicular to the nebular symmetry axis, at odds with the expectation that the common envelope is ejected in the orbital plane. We find no evidence for such a discrepancy, deriving a binary inclination in agreement with that of the nebula as determined by spatio-kinematic modelling. This makes ETHOS 1 the ninth post-common-envelope planetary nebula in which the binary orbital and nebular symmetry axes have been shown to be aligned, with as yet no known counter-examples. The probability of finding such a correlation by chance is now less than 0.000 02 per cent.
Spontaneous Deracemizations
(ACS Publications, 2021-02-24) Buhse, Thomas; Cruz, José Manuel; Noble-Terán, María E.; Hochberg, David; Ribó, Josep M.; Crusats, Joaquim; Micheau, Jean Claude; National Science Centre, Poland (NCN); Agencia Estatal de Investigación (AEI); Gobierno de Canarias; 0000-0001-5082-0873; 0000-0002-0411-019X; 0000-0001-6258-1726; 0000-0003-3511-4676
Spontaneous deracemizations is a challenging, multidisciplinary subject in current chirality research. In the absence of any chiral inductors, an achiral substance or a racemic composition is driven into an enantioenriched or even homochiral state through a selective energy input, e.g., chemical potential, photoirradiation, mechanical grinding, ultrasound waves, thermal gradients, etc. The most prominent examples of such transformations are the Soai reaction and the Viedma deracemization. In this review, we track the most recent developments in this topic and recall that many other deracemizations have been reported for solutions from mesophases to conglomerate crystallizations. A compiled set of simply available achiral organic, inorganic, organometallic, and MOF compounds, yielding conglomerate crystals, should give the impetus to realize new experiments on spontaneous deracemizations. Taking into account thermodynamic constraints, modeling efforts have shown that structural features alone are not sufficient to describe spontaneous deracemizations. As a guideline of this review, particular attention is paid to the physicochemical origin and symmetry requirements of such processes.
(Sub)mm-Wavelength Observations of Pre-Planetary Nebulae and Young Planetary Nebulae
(Multidisciplinary Digital Publishing Institute (MDPI), 2020-03-10) Sánchez Contreras, C.; National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); 0000-0002-6341-592X; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
This is a non-comprehensive review of observations of pre-Planetary Nebulae (pPNe) and young Planetary Nebulae (yPNe) at (sub)mm-wavelengths, a valuable window for probing multi-phased gas and dust in these objects. This contribution focuses on observations of molecular lines (from carbon monoxide—CO—and other species), and briefly at the end, on hydrogen radio recombination lines from the emerging H ii regions at the center of yPNe. The main goal of this contribution is to show the potential of (sub)mm-wavelength observations of pPNe/yPNe to help the community to devise and develop new observational projects that will bring us closer to a better understanding of these latest stages of the evolution of low-to-intermediate (∼0.8–8
Fast outflows in protoplanetary nebulae and young planetary nebulae observed by Herschel/HIFI
(EDP Sciences, 2021-03-02) Lorenzo, M.; Teyssier, R.; Bujarrabal, V.; García Lario, P.; Alcolea, J.; Verdugo, E.; Marston, A.; Agencia Estatal de Investigación (AEI)
Context. Fast outflows and their interaction with slow shells (generally known as the fossil circumstellar envelope of asymptotic giant branch stars) play an important role in the structure and kinematics of protoplanetary and planetary nebulae (pPNe, PNe). To properly study their effects within these objects, we also need to observe the intermediate-temperature gas, which is only detectable in the far-infrared and submillimetre (submm) transitions.
Aims. We study the physical conditions of the outflows presented in a number of pPNe and PNe, with a focus on their temperature and excitation states.
Methods. We carried out Herschel/HIFI observations in the submm lines of 12CO in nine pPNe and nine PNe and complemented them with low-J CO spectra obtained with the IRAM 30m telescope and taken from the literature. The spectral resolution of HIFI allows us to identify and measure the different nebular components in the line profiles. The comparison with large velocity gradient model predictions was used to estimate the physical conditions of the warm gas in the nebulae, such as excitation conditions, temperature, and density.
Results. We found high kinetic temperatures for the fast winds of pPNe, typically reaching between 75 K and 200 K. In contrast, the high-velocity gas in the sampled PNe is colder, with characteristic temperatures between 25 K and 75 K, and it is found in a lower excitation state. We interpret this correlation of the kinetic temperature and excitation state of fast outflows with the amount of time elapsed since their acceleration (probably driven by shocks) as a consequence of the cooling that occurred during the pPN phase.
