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Lucky spectroscopy, an equivalent technique to lucky imaging. II. Spatially resolved intermediate-resolution blue-violet spectroscopy of 19 close massive binaries using the William Herschel Telescope
Simón-Díaz, S.; Maíz Apellániz, J.; Negueruela, I. +5 more
Context. Many massive stars have nearby companions. These hamper a characterization of massive stars through spectroscopy.
Aims: We continue to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types.
Methods: We used the lucky spectroscopy technique to obtain a large number of short long-sl…
Comparison of Gaia and Hipparcos parallaxes of close visual binary stars and the impact on determinations of their masses
Hussein, Abdallah M.; Al-Wardat, Mashhoor Ahmad; Al-Naimiy, Hamid M. +1 more
Precise measurement of the fundamental parameters of stellar systems, including mass and radius, depends critically on how well the stellar distances are known. Astrometry from space provides parallax measurements of unprecented accuracy, from which distances can be derived, initially from the Hipparcos mission, with a further refinement of that a…
STARCNET: Machine Learning for Star Cluster Identification
Calzetti, Daniela; Adamo, Angela; Messa, Matteo +4 more
We present a machine learning (ML) pipeline to identify star clusters in the multicolor images of nearby galaxies, from observations obtained with the Hubble Space Telescope as part of the Treasury Project LEGUS (Legacy ExtraGalactic Ultraviolet Survey). STARCNET (STAR Cluster classification NETwork) is a multiscale convolutional neural network (C…
A deep learning approach to quasar continuum prediction
Liu, Bin; Bordoloi, Rongmon
We present a novel intelligent quasar continuum neural network (iQNet), predicting the intrinsic continuum of any quasar in the rest-frame wavelength range of $1020 \, {\mathring{\rm A}}\le \lambda _{\text{rest}} \le 1600 \, {\mathring{\rm A}}$ . We train this network using high-resolution Hubble Space Telescope/Cosmic Origin Spectrograph ultravio…
Estimation of surface temperatures on Mercury in preparation of the MERTIS experiment onboard BepiColombo
Hiesinger, Harald; Helbert, Jörn; Bauch, Karin E. +1 more
The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is part of the payload on the joint ESA-JAXA BepiColombo Mission, launched in October 2018. The spectrometer is designed to map surface composition, identify rock-forming minerals, map surface mineralogy, and study surface temperature variations. The surface of Mercury undergoes lar…
The Pristine survey - XIV. Chemical analysis of two ultra-metal-poor stars
Bonifacio, P.; Caffau, E.; Jablonka, P. +15 more
Elemental abundances of the most metal-poor stars reflect the conditions in the early Galaxy and the properties of the first stars. We present a spectroscopic follow-up of two ultra-metal-poor stars ([Fe/H] < -4.0) identified by the survey Pristine: Pristine 221.8781+9.7844 and Pristine 237.8588+12.5660 (hereafter Pr 221 and Pr 237, respectivel…
Possible single-armed spiral in the protoplanetary disk around HD 34282
Ménard, F.; van der Plas, G.; Avenhaus, H. +17 more
Context. During the evolution of protoplanetary disks into planetary systems we expect to detect signatures that trace mechanisms such as planet-disk interaction. Protoplanetary disks display a large variety of structures in recently published high-spatial resolution images. However, the three-dimensional morphology of these disks is often difficu…
The symbiotic recurrent nova V3890 Sgr: binary parameters and pre-outburst activity
Udalski, A.; Mikołajewska, J.; Iłkiewicz, K. +4 more
We present and analyse optical photometry and high-resolution Southern African Large Telescope spectra of the symbiotic recurrent nova V3890 Sgr at quiescence. The orbital period, P = 747.6 d, has been derived from both photometric and spectroscopic data. Our double-line spectroscopic orbits indicate that the mass ratio is q = Mg/M…
A revisited study of Cepheids in open clusters in the Gaia era
Grebel, Eva K.; Medina, Gustavo E.; Lemasle, Bertrand
In this paper, we revisit the problem of identifying bona fide cluster Cepheids by performing an all-sky search for Cepheids associated with open clusters and making use of state-of-the-art catalogued information for both Cepheids and clusters, based on the unparalleled astrometric precision of the second and early third data releases of the Gaia …
Deciphering Star Cluster Evolution by Shape Morphology
Hu, Qingshun; Zhang, Yu; Esamdin, Ali +2 more
We analyze the morphological evolution of open clusters and provide shape parameters for 265 open clusters. The results show that the overall shape of sample clusters becomes more elliptical as they grow older, while their core remains circular or slightly trending to circular. There is a negative correlation of the ellipticities with the number o…