Search Publications
Testing the relativistic Doppler boost hypothesis for the binary candidate quasar PG1302-102 with multiband Swift data
Stern, Daniel; Graham, Matthew J.; Haiman, Zoltán +4 more
The bright quasar PG1302-102 has been identified as a candidate supermassive black hole binary from its near-sinusoidal optical variability. While the significance of its optical periodicity has been debated due to the stochastic variability of quasars, its multiwavelength variability in the ultraviolet (UV) and optical bands is consistent with re…
Metallicity has followed local gravitational potential of galaxies since z = 3
Christensen, L.; Møller, P.
The MZ relation between stellar mass (M*) and metallicity (Z) of nearby galaxies has been described as both a global and local property, I.e. valid also on sub-galaxy scales. Here, we show that Z has remained a local property, following the gravitational potential, since z = 3. In absorption, the MZ relation has been well studied, and w…
Failed prominence eruptions near 24 cycle maximum
Filippov, B.
We analyse 16 failed filament eruptions observed near 24 solar cycle maximum from 2013 May to 2014 July. No significant rotation of filament spines is observed during the ascent in all studied failed eruptions, which does not support kink-instability mechanism of triggering the eruptions. We calculate potential magnetic field distributions in the …
Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra
Nagel, E.; Amado, P. J.; Caballero, J. A. +10 more
With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultra-stable, double-channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar atm…
Chemical abundances of open clusters from high-resolution infrared spectra - II. NGC 752
Sneden, C.; Pilachowski, C. A.; Mace, G. N. +9 more
We present a detailed near-infrared chemical abundance analysis of 10 red giant members of the Galactic open cluster NGC 752. High-resolution (R ≃ 45000) near-infrared spectral data were gathered with the Immersion Grating Infrared Spectrograph, providing simultaneous coverage of the complete H and K bands. We derived the abundances of H-burning (…
The PDR structure and kinematics around the compact H II regions S235 A and S235 C with [C II], [13C II], [O I], and HCO+ line profiles
Schneider, N.; Samal, M. R.; Okada, Y. +11 more
The aim of this work is to study structure and gas kinematics in the photodissociation regions (PDRs) around the compact H II regions S235 A and S235 C. We observe the [C II], [13C II], and [O I] line emission, using SOFIA/upGREAT, and complement them by data of HCO+ and CO. We use the [13C II] line to measure the …
The nuclear architecture of NGC 4151: on the path toward a universal outflow mechanism in light of NGC 1068
Williams, D. R. A.; Steiner, J. E.; May, D. +2 more
We report near-infrared integral field spectroscopic observations of the active galactic nucleus NGC 4151 with archive data from the NIFS-Gemini North Telescope. We have selected best-seeing observations (≲0.3 arcsec) that, allied to our methodology of image processing techniques, show structures with spatial resolution comparable to those of the …
NuSTAR observations of four nearby X-ray faint AGNs: low luminosity or heavy obscuration?
Harrison, F. A.; Stern, D.; Alexander, D. M. +20 more
We present NuSTAR (Nuclear Spectroscopic Telescope Array) observations of four active galactic nuclei (AGNs) located within 15 Mpc. These AGNs, namely ESO 121-G6, NGC 660, NGC 3486, and NGC 5195, have observed X-ray luminosities of L2-10 keV,obs ≲ 1039 erg s-1, classifying them as low-luminosity AGN (LLAGN). We per…
The AGN fuelling/feedback cycle in nearby radio galaxies - III. 3D relative orientations of radio jets and CO discs and their interaction
Davis, Timothy A.; Bureau, Martin; Paladino, Rosita +4 more
This is the third paper of a series exploring the multifrequency properties of a sample of eleven nearby low-excitation radio galaxies (LERGs) in the southern sky. We are conducting an extensive study of different galaxy components (stars, dust, warm and cold gas, radio jets) with the aim of better understanding the AGN fuelling/feedback cycle in …
Helium abundances and its radial gradient from the spectra of H II regions and ring nebulae of the Milky Way
Méndez-Delgado, J. E.; Arellano-Córdova, K. Z.; García-Rojas, J. +2 more
We determine the radial abundance gradient of helium in the disc of the Galaxy from published spectra of 19 H II regions and ring nebulae surrounding massive O-type stars. We revise the Galactocentric distances of the objects considering Gaia DR2 parallaxes (Gaia Collaboration 2018) and determine the physical conditions and the ionic abundance of …