- Published on Tuesday, 20 February 2018 08:00
In section 1. Letters to the Editor
Discovery of a dual AGN at z~3.3 with 20 kpc separation
In the standard CDM cosmological model, galaxies form through mergers in a hierarchical scenario. Since each galaxy nucleus hosts a super massive black hole, a large number of dual AGN, with separations of a few kpc, is expected. However they have been elusive up to now. Thanks to MUSE on the VLT, the authors report the detection of one of the closest pairs of AGN known at z > 3. The object, dubbed Jil, meaning “neighbor” in the Klingon language (Star Trek universe) is a narrow-line emitter within the 120kpc-wide Ly-alpha nebula of the luminous radio-quiet QSO LBQS 0302-0019 at z = 3.3. Jill emits several high ionization narrow emission lines (HeII, CIV, CIII) and is only 20 kpc away from the QSO in projection. Emission-line diagnostics confirm that the source is likely powered by photoionization of an obscured AGN three orders of magnitude fainter than the QSO.
- Published on Thursday, 08 February 2018 08:00
In section 1. Letters to the Editor
The CARMENES search for exoplanets around M dwarfs. HD147379 b: A nearby Neptune in the temperate zone of an early-M dwarf
A first planet for CARMENES! The closest planets to our solar system orbit M dwarfs. It is likely that the closest planets with liquid water on their surface also orbit M dwarfs. CARMENES is a spectrometer located in Calar Alto (Spain) which is dedicated to the follow-up of these faint stars using radial velocimetry in the infrared. This article by Reiners et al. present its first detection of such a planet around an M-dwarf: a Neptune-mass planet with an orbital period of 86 days around a 0.5 solar mass star. This may herald many more planets to be discovered thorough exploration of our galactic neighborhood.
- Published on Monday, 08 January 2018 08:00
In section 10: Planets and planetary systems
Dome C ultracarbonaceous Antarctic micrometeorites: Infrared and Raman fingerprints
Interplanetary dust particles travel across the solar system and represent the largest mass flux of extraterrestrial material falling on the Earth. Their small sizes (hundreds of microns or less) make their collection and analysis challenging. Dartois et al. analyze a small subset of these particles acquired from the Concordia/CSNSM micrometeorites collection performed in Antarctica, the so-called UltraCarbonaceous Antarctic MicroMeteorites (UCAMMs). These particles contain a large amount of nitrogen-rich organic matter not found elsewhere in extraterrestrial matter and probably originating from the outer solar system. The analyses show that both the C/Si and N/C abundance ratios in UCAMMs are the highest found in the solar system and are above the interstellar medium cosmic abundances. These finding are most important to understand the composition of outer solar system objects and the origin of primitive organics.
- Published on Friday, 05 January 2018 08:00
In section 6. Interstellar and circumstellar matter
Direct mapping of the temperature and velocity gradients in discs
The authors present a new, empirical method for locating the CO-isotopologue emitting surfaces from high spectral and spatial resolution ALMA observations of protoplanetary disks. They have applied this method to the disk surrounding IM Lupi, and present the first model-independent measurements of the radial and vertical gradients of temperature and velocity in a protoplanetary disk. The derived disk structure is consistent with that of an irradiated self-similar disk, in which the temperature increases and the velocity decreases towards the disk surface. The authors have also mapped the vertical CO snow line, which is located at approximately one gas scale-height at radii between 150 and 300 au, with a CO freeze-out temperature of 21 ± 2 K. In the outer disk (>300 au), the velocity rotation field becomes significantly sub-Keplerian, in agreement with the expected steeper pressure gradient. This should result in a very efficient inward migration of large dust grains, explaining the lack of millimeter continuum emission beyond 300 au.