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Register a new userAnalysis of Selected Runaway Stars in the Orion Nebula Based on Data from the Gaia EDR3 Catalogue
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We have performed Monte Carlo simulations of the trajectories of several runaway stars using their parallaxes and proper motions from the Gaia EDR3 catalogue. We have confirmed the hypothesis that the stars AE Aur and $mu$Col are a product of the multiple system breakup $sim$2.5 Myr ago and the Orion Trapezium may be the parent cluster for this pair of stars. We show that the data from the Gaia EDR3 catalogue for the star $iota$Ori, mainly the parallax, do not allow us to talk about the breakup of the multiple system of AE Aur, $mu$Col, and $iota$Ori. The existence of close pair encounters between the stars HD 30112 and HD 43112 $sim$1 Myr ago has been confirmed. Close triple encounters confirm the hypothesis that the stars HD 30112 and HD 43112 escaped from the parent cluster Col 69. We show that the stars HIP 28133 and TYC 5368-1541-1 have a nonzero probability of escape from the region within 10 pc of the center of the Orion Trapezium cluster and a fairly high probability (about 8%) that they were both at distances less than 20 pc from the center of the Orion Trapezium $sim$2.5 Myr ago. It has been established for the first time that the stars Gaia EDR3 3021115184676332288 and Gaia EDR3 2983790269606043648 have a probability of about 0.5% that they broke up as a binary system $sim$1.1 Myr ago. The star Gaia EDR3 3021115184676332288 has a probability of about 16% that it escaped from the region within 10 pc of the center of the Orion Trapezium cluster $sim$1 Myr ago.
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We explore scenarios for the dynamical ejection of stars BN and x from source I in the Kleinmann-Low nebula of the Orion Nebula Cluster (ONC), which is important for being the closest region of massive star formation. This ejection would cause source I to become a close binary or a merger product of two stars. We thus consider binary-binary encounters as the mechanism to produce this event. By running a large suite of $N$-body simulations, we find that it is nearly impossible to match the observations when using the commonly adopted masses for the participants, especially a source I mass of $7:{rm{M}}_odot$. The only way to recreate the event is if source I is more massive, i.e., $sim20:{rm{M}}_odot$. However, even in this case, the likelihood of reproducing the observed system is low. We discuss the implications of these results for understanding this important star-forming region.
Young nearby runaway stars are suitable to search for their place of origin and possibly associated objects, for example neutron stars. Tetzlaff, Neuhauser & Hohle (2011) selected young ($le 50$ Myr) runaway star candidates from Hipparcos, for which they had estimated the ages from the location in the Hertzsprung-Russell diagram and evolutionary models. Here, we redetermine or constrain their young ages more precisely not only by using the new Gaia DR2 data, but also by measuring lithium, which is a youth indicator. For 308 stars, we took spectra to search for the strong resonance doublet of the lithium-7 isotope at 6708 $unicode{xC5}$. The spectra were taken with the Echelle spectrograph FLECHAS at the University Observatory Jena between February 2015 and June 2018 and with TRES between April 2011 and June 2017 at the Fred L. Whipple Observatory. We found 208 stars with significant occurrence of lithium in their spectra, and five possess a possible age younger or about 50 Myr. Three of these targets are even closer than GJ 182, the nearest known runaway star at about 24 pc. Theses stars are young runaway stars suitable for further investigation of their origin from either a dynamical or supernova ejection.
We produce a clean and well-characterised catalogue of objects within 100,pc of the Sun from the G Early Data Release 3. We characterise the catalogue through comparisons to the full data release, external catalogues, and simulations. We carry out a first analysis of the science that is possible with this sample to demonstrate its potential and best practices for its use. The selection of objects within 100,pc from the full catalogue used selected training sets, machine-learning procedures, astrometric quantities, and solution quality indicators to determine a probability that the astrometric solution is reliable. The training set construction exploited the astrometric data, quality flags, and external photometry. For all candidates we calculated distance posterior probability densities using Bayesian procedures and mock catalogues to define priors. Any object with reliable astrometry and a non-zero probability of being within 100,pc is included in the catalogue. We have produced a catalogue of NFINAL objects that we estimate contains at least 92% of stars of stellar type M9 within 100,pc of the Sun. We estimate that 9% of the stars in this catalogue probably lie outside 100,pc, but when the distance probability function is used, a correct treatment of this contamination is possible. We produced luminosity functions with a high signal-to-noise ratio for the main-sequence stars, giants, and white dwarfs. We examined in detail the Hyades cluster, the white dwarf population, and wide-binary systems and produced candidate lists for all three samples. We detected local manifestations of several streams, superclusters, and halo objects, in which we identified 12 members of G Enceladus. We present the first direct parallaxes of five objects in multiple systems within 10,pc of the Sun.
Aims. Planetary nebulae (PNe) are a brief phase of stellar evolution and as such some of the rarest objects in our galaxy. Accurate identification of PN central stars (CSPNe) in large surveys such as Gaia is key to exploiting the scientific potential of those surveys for the study of PNe and stellar evolution. Methods. We apply our automated search method to identify source detections corresponding to CSPNe and compact PNe in the recently released Gaia Early Data Release 3 (EDR3). The method is updated to incorporate photometric uncertainties. Results. The new catalogue offers improved completeness and accuracy over the previous one, and will continue to be valid for the upcoming Gaia Data Release 3 (DR3). The identification of EDR3 sources unlocks the improved astrometry and photometry stemming from calibration updates and a longer mission duration, even for sources that have previously been identified.
We present a catalogue of white dwarf candidates selected from Gaia early data release three (EDR3). We applied several selection criteria in absolute magnitude, colour, and Gaia quality flags to remove objects with unreliable measurements while preserving most stars compatible with the white dwarf locus in the Hertzsprung-Russell diagram. We then used a sample of over 30 000 spectroscopically confirmed white dwarfs and contaminants from the Sloan Digital Sky Survey (SDSS) to map the distribution of these objects in the Gaia absolute magnitude-colour space. Finally, we adopt the same method presented in our previous Gaia DR2 work to calculate a probability of being a white dwarf (Pwd) for $simeq$1.3 million sources which passed our quality selection. The Pwd values can be used to select a sample of $simeq$359 000 high-confidence white dwarf candidates in the magnitude range 8< G <21. We calculated stellar parameters (effective temperature, surface gravity, and mass) for all these stars by fitting Gaia astrometry and photometry with synthetic models. We estimate an upper limit of 93 per cent for the overall completeness of our catalogue for white dwarfs with G $leq$20 mag and effective temperature (Teff)>7000K, at high Galactic latitudes (|b|>20{deg}). Alongside the main catalogue we include a reduced-proper-motion extension containing $simeq$10 200 white dwarf candidates with unreliable parallax measurements which could, however be identified on the basis of their proper motion. We also performed a cross-match of our catalogues with SDSS DR16 spectroscopy and provide spectral classification based on visual inspection for all resulting matches.
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