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Formation of cometary O2 ice and related ice species on grain surfaces in the midplane of the pre-solar nebula
Walsh, Catherine; Eistrup, Christian
Context. Detection of abundant O2 at 1-10% relative to H2O ice in the comae of comets 1P/Halley and 67P/Churyumov-Gerasimenko has motivated attempts to explain the origin of the high O2 ice abundance. Recent chemical modelling of the outer, colder regions of a protoplanetary disk midplane has shown production of O<…
A high-mass planetary nebula in a Galactic open cluster
Zijlstra, A. A.; Parker, Q. A.; Fragkou, V. +2 more
Planetary nebulae are the ionized ejected envelopes surrounding the remnant cores of dying stars. Theory predicts that main-sequence stars of one to about eight solar masses may eventually form planetary nebulae. Until now, this has not been confirmed at the higher end of the mass range. Here we report that the planetary nebula BMP J1613-5406 is a…
Fundamental parameters and evolutionary status of the magnetic chemically peculiar stars HD 188041 (V1291 Aquilae), HD 111133 (EP Virginis), and HD 204411: spectroscopy versus interferometry
Shulyak, D.; Ryabchikova, T.; Perraut, K. +4 more
The determination of fundamental parameters of stars is one of the main tasks of astrophysics. For magnetic chemically peculiar stars, this problem is complicated by the anomalous chemical composition of their atmospheres, which requires special analysis methods. We present the results of the effective temperature, surface gravity, abundance, and …
Mid-infrared evolution of η Carinae from 1968 to 2018
Gull, T. R.; Hillier, D. J.; Asmus, D. +6 more
η Car is one of the most luminous and massive stars in our Galaxy and is the brightest mid-IR source in the sky outside our solar system. Since the late 1990s, the central source has dramatically brightened at UV and optical wavelengths. This might be explained by a decrease in circumstellar dust extinction. We aim to establish the mid-IR flux evo…
H.E.S.S. and Suzaku observations of the Vela X pulsar wind nebula
Santangelo, A.; Quirrenbach, A.; Bregeon, J. +222 more
Context. Pulsar wind nebulae (PWNe) represent the most prominent population of Galactic very-high-energy gamma-ray sources and are thought to be an efficient source of leptonic cosmic rays. Vela X is a nearby middle-aged PWN, which shows bright X-ray and TeV gamma-ray emission towards an elongated structure called the cocoon.
Aims: Since TeV …
First detections of H13CO+ and HC15N in the disk around HD 97048. Evidence for a cold gas reservoir in the outer disk
Booth, Alice S.; Ilee, John D.; Walsh, Catherine
Observations of different molecular lines in protoplanetary disks provide valuable information on the gas kinematics, as well as constraints on the radial density and temperature structure of the gas. With ALMA we have detected H13CO+ (J = 4-3) and HC15N (J = 4-3) in the HD 97048 protoplanetary disk for the first t…
The HADES RV programme with HARPS-N at TNG. XI. GJ 685 b: a warm super-Earth around an active M dwarf
Rebolo, R.; Ribas, I.; Scandariato, G. +23 more
Context. Small rocky planets seem to be very abundant around low-mass M-type stars. Their actual planetary population is however not yet precisely understood. Currently, several surveys aim to expand the statistics with intensive detection campaigns, both photometric and spectroscopic.
Aims: The HADES program aims to improve the current stati…
Discovery of kilogauss magnetic fields on the nearby white dwarfs WD 1105-340 and WD 2150+591
Bagnulo, S.; Landstreet, J. D.
Magnetic fields are present in roughly 10% of white dwarfs. These fields affect the structure and evolution of such stars, and may provide clues about their earlier evolution history. Particularly important for statistical studies is the collection of high-precision spectropolarimetric observations of (1) complete magnitude-limited samples and (2)…
Carbon and Oxygen Isotopic Ratios. II. Semiregular Variable M Giants
Pilachowski, Catherine A.; Lambert, David L.; Hinkle, Kenneth H. +3 more
Carbon and oxygen isotopic ratios are reported for a sample of 51 SRb- and Lb-type variable asymptotic giant branch stars. Vibration-rotation first- and second-overtone CO lines in 1.5-2.5 µm spectra were measured to derive isotopic ratios for 12C/13C, 16O/17O, and 16O/18O. Co…
The Substructures in the Local Stellar Halo from Gaia and LAMOST
Donlon, Thomas; Du, Cuihua; Li, Hefan +2 more
Based on the second Gaia data release and spectroscopy from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope Data, we identified 20,089 halo stars kinematically and chemically. The halo streams in the solar neighborhood could be detected in the space of energy and angular momentum. We reshuffle the velocities of these stars to determi…