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Deep rest-frame far-UV spectroscopy of the giant Lyman α emitter `Himiko'
Nørgaard-Nielsen, H. U.; Fynbo, J. P. U.; Ouchi, M. +3 more
We present deep 10 h VLT/XSHOOTER spectroscopy for an extraordinarily luminous and extended Ly α emitter at z = 6.595 referred to as Himiko and first discussed by Ouchi et al., with the purpose of constraining the mechanisms powering its strong emission. Complementary to the spectrum, we discuss near-infrared imaging data from the CANDELS survey. …
On the Origin of Wind Line Variability in O Stars
Massa, D.; Prinja, R. K.
We analyze 10 UV time series for five stars that fulfill specific sampling and spectral criteria to constrain the origin of large-scale wind structure in O stars. We argue that excited state lines must arise close to the stellar surface and are an excellent diagnostic complement to resonance lines which, due to radiative transfer effects, rarely s…
Late Noachian fluvial erosion on Mars: Cumulative water volumes required to carve the valley networks and grain size of bed-sediment
Rosenberg, Eliott N.; Head, James W., III
Our goal is to quantify the cumulative water volume that was required to carve the Late Noachian valley networks on Mars. We employ an improved methodology in which fluid/sediment flux ratios are based on empirical data, not assumed. We use a large quantity of data from terrestrial rivers to assess the variability of actual fluid/sediment flux sed…
On the proper kinetic quadrupole CMB removal and the quadrupole anomalies
Notari, Alessio; Quartin, Miguel
It has been pointed out recently that the quadrupole-octupole alignment in the CMB data is significantly affected by the so-called kinetic Doppler quadrupole (DQ), which is the temperature quadrupole induced by our proper motion. Assuming our velocity is the dominant contribution to the CMB dipole we have v/c=β=(1.231 ± 0.003) × 10-3, w…
Orbital elements of the material surrounding comet 67P/Churyumov-Gerasimenko
Jorda, L.; Lamy, P. L.; Lara, L. M. +44 more
Context. We investigate the dust coma within the Hill sphere of comet 67P/Churyumov-Gerasimenko.
Aims: We aim to determine osculating orbital elements for individual distinguishable but unresolved slow-moving grains in the vicinity of the nucleus. In addition, we perform photometry and constrain grain sizes.
Methods: We performed astrome…
Herschel observations of extreme OH/IR stars. The isotopic ratios of oxygen as a sign-post for the stellar mass
Waters, L. B. F. M.; Olofsson, H.; Blommaert, J. +10 more
Aims: The late stages of stellar evolution are mainly governed by the mass of the stars. Low- and intermediate-mass stars lose copious amounts of mass during the asymptotic giant branch (AGB) which obscure the central star making it difficult to study the stellar spectra and determine the stellar mass. In this study, we present observational …
Far-infrared study of K giants in the solar neighborhood: Connection between Li enrichment and mass-loss
Zhao, G.; Muthumariappan, C.; Bharat Kumar, Yerra +1 more
Context. A small group of red giant branch (RGB) stars are known to have anomalous Li enhancement whose origin is still not well understood. Some studies have proposed that the Li enhancement in RGB stars is correlated to their far-IR excess, a result of mass loss. Studies to confirm such a correlation have a significant bearing on our understandi…
New members of the TW Hydrae Association and two accreting M-dwarfs in Scorpius-Centaurus
Murphy, Simon J.; Bento, Joao; Lawson, Warrick A.
We report the serendipitous discovery of several young mid-M stars found during a search for new members of the 30-40 Myr-old Octans Association. Only one of the stars may be considered a possible Octans(-Near) member. However, two stars have proper motions, kinematic distances, radial velocities, photometry and Li I λ6708 measurements consistent …
The Evolution of Inner Disk Gas in Transition Disks
France, K.; Schneider, P. C.; Alexander, R. D. +2 more
Investigating the molecular gas in the inner regions of protoplanetary disks (PPDs) provides insight into how the molecular disk environment changes during the transition from primordial to debris disk systems. We conduct a small survey of molecular hydrogen (H2) fluorescent emission, using 14 well-studied Classical T Tauri stars at two…
Testing Density Wave Theory with Resolved Stellar Populations around Spiral Arms in M81
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +4 more
Stationary density waves rotating at a constant pattern speed {{{Ω }}}{{P}} would produce age gradients across spiral arms. We test whether such age gradients are present in M81 by deriving the recent star formation histories (SFHs) of 20 regions around one of M81's grand-design spiral arms. For each region, we use resolved stellar popu…