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Cloud Structure of the Nearest Brown Dwarfs. II. High-amplitude Variability for Luhman 16 A and B in and out of the 0.99 µm FeH feature
Apai, Dániel; Crossfield, Ian J. M.; Radigan, Jacqueline +4 more
The re-emergence of the 0.99 µm FeH feature in brown dwarfs of early- to mid-T spectral type has been suggested as evidence for cloud disruption where flux from deep, hot regions below the Fe cloud deck can emerge. The same mechanism could account for color changes at the L/T transition and photometric variability. We present the first obser…
A Comprehensive Study of Broad Absorption Line Quasars. I. Prevalence of HeI* Absorption Line Multiplets in Low-ionization Objects
Yuan, Weimin; Shu, Xinwen; Zhou, Hongyan +13 more
Neutral helium multiplets, He i* λ λ 3189,3889,10830, are very useful diagnostics for the geometry and physical conditions of the absorbing gas in quasars. So far only a handful of He i* detections have been reported. Using a newly developed method, we detected the He i*λ 3889 absorption line in 101 sources of a well-defined sample of 285 Mg ii br…
The spatially-resolved star formation history of the M31 outer disc
Lewis, Geraint F.; McConnachie, Alan W.; Ibata, Rodrigo A. +4 more
We present deep Hubble Space Telescope Advanced Camera for Surveys observations of the stellar populations in two fields lying at 20 and 23 kpc from the centre of M31 along the south-west semimajor axis. These data enable the construction of colour-magnitude diagrams reaching the oldest main-sequence turn-offs (∼13 Gyr) which, when combined with a…
Geomorphology and spectrophotometry of Philae's landing site on comet 67P/Churyumov-Gerasimenko
Jorda, L.; Bertaux, J. -L.; Lamy, P. +52 more
Context. On 12 November 2014 the European mission Rosetta succeeded in delivering a lander, named Philae, on the surface of one of the smallest, low-gravity and most primitive bodies of the solar system, the comet 67P/Churyumov-Gerasimenko (67P).
Aims: The aim of this paper is to provide a comprehensive geomorphological and spectrophotometric…
Non-conservative evolution in Algols: where is the matter?
Baes, M.; Jorissen, A.; Siess, L. +3 more
Context. There is indirect evidence of non-conservative evolutions in Algols. However, the systemic mass-loss rate is poorly constrained by observations and generally set as a free parameter in binary-star evolution simulations. Moreover, systemic mass loss may lead to observational signatures that still need to be found.
Aims: Within the "ho…
Stellar cycles from photometric data: CoRoT stars
Catelan, M.; Ferreira Lopes, C. E.; De Medeiros, J. R. +3 more
Context. Until a few years ago, the amplitude variation in the photometric data had been explored to a limited extent mainly because of time resolution and photometric sensitivity limitations. This investigation is now possible thanks to the Kepler and CoRoT databases which provide a unique set of data for studying the nature of stellar variabilit…
Outflow of low-energy ions and the solar cycle
André, M.; Eriksson, A. I.; Li, K.
Magnetospheric ions with energies less than tens of eV originate from the ionosphere. Positive low-energy ions are complicated to detect onboard sunlit spacecraft at higher altitudes, which often become positively charged to several tens of volts. We use two Cluster spacecraft and study low-energy ions with a technique based on the detection of th…
Overturning the Case for Gravitational Powering in the Prototypical Cooling Lyα Nebula
Momcheva, Ivelina; Brammer, Gabriel B.; Fynbo, Johan P. U. +2 more
The Nilsson et al. Lyα nebula has often been cited as the most plausible example of an Lyα nebula powered by gravitational cooling. In this paper, we bring together new data from the Hubble Space Telescope and the Herschel Space Observatory as well as comparisons to recent theoretical simulations in order to revisit the questions of the local envi…
The Host Galaxies of X-Ray Quasars are Not Strong Star Formers
Hasinger, G.; Li, Y.; Owen, F. N. +4 more
We use ultradeep SCUBA-2 850 µm observations (∼0.37 mJy rms) of the 2 Ms Chandra Deep Field-North (CDF-N) and 4 Ms Chandra Deep Field-South X-ray fields to examine the amount of dusty star formation taking place in the host galaxies of high-redshift X-ray active galactic nuclei (AGNs). Supplementing with COSMOS, we measure the submillimeter …
A Connection between Plasma Conditions near Black Hole Event Horizons and Outflow Properties
Gandhi, P.; Bernardini, F.; Casella, P. +9 more
Accreting black holes are responsible for producing the fastest, most powerful outflows of matter in the universe. The formation process of powerful jets close to black holes is poorly understood, and the conditions leading to jet formation are currently hotly debated. In this paper, we report an unambiguous empirical correlation between the prope…