Thomas Henning

Single conjugate adaptive optics for METIS

METIS is the Mid-infrared Extremely large Telescope Imager and Spectrograph, one of the first generation instruments of ESO’s 39m ELT. All scientific observing modes of METIS require adaptive optics (AO) correction close to the diffraction limit. Demanding constraints are introduced by the foreseen coronagraphy modes, which require highest angular resolution and PSF stability. Further design drivers for METIS and its AO system are imposed by the wavelength regime: observations in the thermal infrared require an elaborate thermal, baffling and masking concept. METIS will be equipped with a Single-Conjugate Adaptive Optics (SCAO) system. An integral part of the instrument is the SCAO module. It will host a pyramid type wavefront sensor, operating in the near-IR and located inside the cryogenic environment of the METIS instrument. The wavefront control loop as well as secondary control tasks will be realized within the AO Control System, as part of the instrument. Its main actuators will be the adaptive quaternary mirror and the field stabilization mirror of the ELT. In this paper we report on the phase B design work for the METIS SCAO system; the opto-mechanical design of the SCAO module as well as the control loop concepts and analyses. Simulations were carried out to address a number of important aspects, such as the impact of the fragmented pupil of the ELT on wavefront reconstruction. The trade-off that led to the decision for a pyramid wavefront sensor will be explained, as well as the additional control tasks such as pupil stabilization and compensation of non-common path aberrations.

Detecting Gaps in Protoplanetary Disks with MIDI at the VLTI

Numerical simulations show that a Jupiter mass planet is able to dig the gas material along its path. Resulting from this, a density gap is produced within the disk which may represent a large-scale density feature.

The installation and ongoing commissioning of the MATISSE mid-infrared interferometer at the ESO Very Large Telescope Observatory

MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 μm, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with the four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ~ 30 to R ~ 5000. Here, we remind the concept, the instrumental design, and the main features of MATISSE. We also describe the last months of preparation, the status of the instrument, which was shipped to Cerro Paranal on the site of the ESO Very Large Telescope in October 2017, and the expected schedule for the opening to the community. The instrument is currently in its Commissioning phase. A complementary dedicated article details the Commissioning results, which include the first performance estimates on sky.

Kinematic and thermal structure at the onset of high-mass star formation - ISOSS23053

Within the ’earliest phases of star formation’ (EPoS) Herschel project, we observed the NH3 inversion lines of 6 very young high-mass star-forming regions at high spatial resolution (3-5′′) with the JVLA. While the Herschel data provide details about the dust continuum, the ammonia data reveal the kinematics and temperatures. Here we present the exciting star-forming clump ISOSS23053 that shows multiple velocity components. We observe a prominent velocity step within the clump, which could be a sign of colliding or converging flows that triggers star formation. Furthermore, we used the JVLA in the C-array configuration to study this source in more detail and we present the first results from the new data. They support the idea of converging flows, as we observe two components in the NH3(1,1) and (2,2) line, whereas the higher excited NH3(3,3) line shows one component that links the two lower excited lines.

Probing Dust around Brown Dwarfs: The Naked LP 944–20 and the Disk of Cha Hα2

We present the first mid-infrared (MIR) detection of a field brown dwarf (BD) and the first ground-based MIR measurements of a disk around a young BD candidate. We prove the absence of warm dust surrounding the field BD LP 944–20. In the case of the young BD candidate Cha Hα2, we find clear evidence for thermal dust emission from a disk. Surprisingly, the object does not exhibit any silicate feature as previously predicted. We show that the flat spectrum can be explained by an optically thick flat dust disk but not by a flared one.

Infrared observations of young massive stars

Infrared observations of young massive stars yield crucial insights on the birth of high-mass stars and their interaction with the parent molecular cloud. Results for IRAS23140+6121, G254.681+0.219, and NGC6334F obtained by near- and mid-infrared imaging are presented for a brief illustration.