Search Publications
Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes
Bobylev, V. V.; Bajkova, A. T.; Krisanova, O. I.
Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active star-forming regions. It also includes young low-mass stars from the Gould Belt region whose radio observations …
Singing Comet Waves in a Solar Wind Convective Electric Field Frame
Goetz, C.; Taylor, M. G. G. T.; Plaschke, F.
The cometary plasma environment at low gas production rates is dominated by highly compressional, large-amplitude magnetic field waves in the 10-100 mHz range. They are thought to be caused by an ion-Weibel instability due to a cross-field current, which is caused by the cometary ions that are accelerated along the solar wind convective electric f…
Derivation of parameters for 3748 FGK stars using H-band spectra from APOGEE Data Release 14
Rojas-Ayala, Bárbara; Delgado Mena, Elisa; Blanco-Cuaresma, Sergi +1 more
Context. The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has observed the H-band spectra of over 200 000 stars with R ∼ 22 000.
Aims: The main motivation for this work is to test an alternative method to the standard APOGEE pipeline (APOGEE Stellar Parameter and Chemical Abundances Pipeline, ASPCAP) to derive parameters in…
No universal connection between the vertical magnetic field and the umbra-penumbra boundary in sunspots
Solanki, S. K.; Lagg, A.; Löptien, B. +1 more
Context. It has been reported that the boundary between the umbra and the penumbra of sunspots occurs at a canonical value of the strength of the vertical magnetic field, independently of the size of the spot. This critical field strength is interpreted to be the threshold for the onset of magnetoconvection.
Aims: Here we investigate the reas…
Physical properties of the fluorine and neutron-capture element-rich PN Jonckheere 900
Otsuka, Masaaki; Hyung, Siek
We performed detailed spectroscopic analyses of a young C-rich planetary nebula (PN) Jonckheere 900 (J900) in order to characterize the properties of the central star and nebula. Of the derived 17 elemental abundances, we present the first determination of eight elemental abundances. We present the first detection of the [F IV] 4059.9 Å, [F V] 13.…
Spatially Resolved UV Diagnostics of AGN Feedback: Radiation Pressure Dominates in a Prototypical Quasar-driven Superwind
Stern, Jonathan; Johnson, Sean D.; Chen, Hsiao-Wen +5 more
Galactic-scale winds driven by active galactic nuclei (AGN) are often invoked to suppress star formation in galaxy evolution models, but the mechanisms driving these outflows are hotly debated. Two key AGN feedback models are (1) radiation pressure accelerating cool gas and (2) a hot outflowing wind entraining the interstellar medium (ISM). Highly…
Spectroscopic analysis of accretion/ejection signatures in the Herbig Ae/Be stars HD 261941 and V590 Mon
Lebreton, Y.; Alencar, S. H. P.; Alecian, E. +2 more
Herbig Ae/Be (HAeBe) stars are the intermediate-mass analogues of low-mass T Tauri stars. Both groups may present signs of accretion, outflow, and IR excess related to the presence of circumstellar discs. Magnetospheric accretion models are generally used to describe accreting T Tauri stars, which are known to have magnetic fields strong enough to…
Dark Energy Survey identification of a low-mass active galactic nucleus at redshift 0.823 from optical variability
De Vicente, Juan; García-Bellido, Juan; Gaztanaga, Enrique +57 more
We report the identification of a low-mass active galactic nucleus (AGN), DES J0218-0430, in a redshift z = 0.823 galaxy in the Dark Energy Survey (DES) Supernova field. We select DES J0218-0430 as an AGN candidate by characterizing its long-term optical variability alone based on DES optical broad-band light curves spanning over 6 yr. An archival…
A Modern Guide to Quantitative Spectroscopy of Massive OB Stars
Simón-Díaz, Sergio
Quantitative spectroscopy is a powerful technique from which we can extract information about the physical properties and surface chemical composition of stars. In this chapter, I guide the reader through the main ideas required to get initiated in the learning process to become an expert in the application of state-of-the-art quantitative spectro…
Modeling Photoionized Turbulent Material in the Circumgalactic Medium. II. Effect of Turbulence within a Stratified Medium
Safarzadeh, Mohammadtaher; Buie, Edward, II; Gray, William J. +1 more
The circumgalactic medium (CGM) of nearby star-forming galaxies shows clear indications of O VI absorption accompanied by little to no detectable N V absorption. This unusual spectral signature, accompanied by highly nonuniform absorption from lower-ionization-state species, indicates that the CGM must be viewed as a dynamic, multiphase medium, su…