3D shape of Orion A from Gaia DR2 Großschedl, Josefa E.; Alves, João; Meingast, Stefan ...
Astronomy and astrophysics (Berlin),
11/2018, Letnik:
619
Journal Article
Recenzirano
Odprti dostop
We use the Gaia DR2 distances of about 700 mid-infrared selected young stellar objects in the benchmark giant molecular cloud Orion A to infer its 3D shape and orientation. We find that Orion A is ...not the fairly straight filamentary cloud that we see in (2D) projection, but instead a cometary-like cloud oriented toward the Galactic plane, with two distinct components: a denser and enhanced star-forming (bent) Head, and a lower density and star-formation quieter ∼75 pc long Tail. The true extent of Orion A is not the projected ∼40 pc but ∼90 pc, making it by far the largest molecular cloud in the local neighborhood. Its aspect ratio (∼30:1) and high column-density fraction (∼45%) make it similar to large-scale Milky Way filaments (“bones”), despite its distance to the galactic mid-plane being an order of magnitude larger than typically found for these structures.
VISIONS: the VISTA Star Formation Atlas Meingast, Stefan; Alves, João; Bouy, Hervé ...
Astronomy and astrophysics (Berlin),
05/2023, Letnik:
673
Journal Article
Recenzirano
Odprti dostop
VISIONS is an ESO public survey of five nearby (
d
< 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, ...Ophiuchus, and Orion. The survey was carried out with the Visible and Infrared Survey Telescope for Astronomy (VISTA), using the VISTA Infrared Camera (VIRCAM), and collected data in the near-infrared passbands
J
(1.25 μm), H (1.65 μm), and
K
S
(2.15 μm). With a total on-sky exposure time of 49.4h VISIONS covers an area of 650 deg
2
, it is designed to build an infrared legacy archive with a structure and content similar to the Two Micron All Sky Survey (2MASS) for the screened star-forming regions. Taking place between April 2017 and March 2022, the observations yielded approximately 1.15 million images, which comprise 19 TB of raw data. The observations undertaken within the survey are grouped into three different subsurveys. First, the wide subsurvey comprises shallow, large-scale observations and it has revisited the star-forming complexes six times over the course of its execution. Second, the deep subsurvey of dedicated high-sensitivity observations has collected data on areas with the largest amounts of dust extinction. Third, the control subsurvey includes observations of areas of low-to-negligible dust extinction. Using this strategy, the VISIONS observation program offers multi-epoch position measurements, with the ability to access deeply embedded objects, and it provides a baseline for statistical comparisons and sample completeness – all at the same time. In particular, VISIONS is designed to measure the proper motions of point sources, with a precision of 1 mas yr
−1
or better, when complemented with data from the VISTA Hemisphere Survey (VHS). In this way, VISIONS can provide proper motions of complete ensembles of embedded and low-mass objects, including sources inaccessible to the optical ESA
Gaia
mission. VISIONS will enable the community to address a variety of research topics from a more informed perspective, including the 3D distribution and motion of embedded stars and the nearby interstellar medium, the identification and characterization of young stellar objects, the formation and evolution of embedded stellar clusters and their initial mass function, as well as the characteristics of interstellar dust and the reddening law.
We describe the evolution and the analysis of the design that led to the development of the Flat-field and wavelength Calibration Unit (FCU) for the Multi-AO Imaging CAmera for Deep Observations ...(MICADO) instrument. MICADO will be one of the first light instruments of the Extremely Large Telescope. The FCU challenge in terms of calibration is related to the large size of the MICADO entrance and final focal plane, ∼200 mm × 200 mm. Such a focal plane scale and its segmentation in 3 × 3 detectors, require significant design modifications with respect to the calibration units of the current and past generation of instruments. The design analysis and ray tracing calculations are complemented with the test and verification of lab prototypes to assess the reliability of the FCU architecture in terms of flat-field illumination uniformity and signal to noise, spectral calibration line coverage and radial velocity stability of the wavelength solution provided to the instrument.
An analysis of four stellar rings Paunzen, Ernst; Florian, Jan; Gütl‐Wallner, Anna ...
Astronomische Nachrichten,
November-December 2018, 2018-11-00, 20181101, Letnik:
339, Številka:
9-10
Journal Article
Recenzirano
About 50 years ago, one thousand ring‐like structures (called stellar‐rings) were discovered by Isserstedt (1968). They were believed to be groups of young stars formed by shell‐like triggered star ...formation, which would make them excellent tracers of spiral arms, for example. Neglected for 40 years, we used highly accurate kinematic, astrometric, and photometric data to investigate the four most prominent stellar rings. The aim is to investigate if those structures are indeed physically related groups of stars. We used proper motions and parallaxes from the Gaia DR2 to calculate distances and to search for common properties. Color‐magnitude diagrams using BVJHKs measurements were investigated and isochrones fitted. None of the four stellar rings consists of a physically related group of young stars. The location of stars in the line‐of‐sight mimics a ring‐like structure on the sky. The color‐magnitude diagrams are typical for an integrated field population and not for a young star cluster, for example. The currently available data are sufficient to analyze ring‐like structures with a high statistical significance. This allows a new search for such structures in the Milky Way.
AnisoCADO is a Python package for generating images of the point spread function (PSF) for the european extremely large telescope (ELT). The code allows the user to set many of the most important ...atmospheric and observational parameters that influence the shape and strehl ratio of the resulting PSF, including but not limited to: the atmospheric turbulence profile, the guide star position for a single conjugate adaptive optics (SCAO) solution, differential telescope pupil transmission, etc. Documentation can be found at https://anisocado.readthedocs.io/en/latest/
The initial mass function (IMF) is an important, yet enigmatic aspect of the star formation process. The two major open questions regarding the IMF are: is the IMF constant regardless of environment? ...Is the IMF a universal property of star formation? The next generation of extremely large telescopes will allow us to observe further, fainter and more compact stellar clusters than is possible with current facilities. In these proceeding we present our study looking at just how much will these future observatories improve our knowledge of the IMF.
Aims. In this work we aim to estimate the lowest stellar mass that MICADO at the ELT will be able to reliably detect given a stellar density and distance. We also show that instrumental effects that ...will play a critical role, and report the number of young clusters that will be accessible for IMF studies in the local Universe with the ELT. Methods. We used SimCADO, the instrument simulator package for the MICADO camera, to generate observations of 56 dense stellar regions with densities similar to the cores of young stellar clusters. We placed the cluster fields at distances between 8 kpc and 5 Mpc from the Earth, implying core densities from 10^2 to 10^5 stars arcsec^-2, and determined the lowest reliably observable mass for each stellar field through point-spread function (PSF) fitting photometry. Results. Our results show that stellar densities of <10^3 stars arcsec^-2 will be easily resolvable by MICADO. The lowest reliably observable mass in the Large Magellanic Cloud will be around 0.1 Msun for clusters with densities <10^3 stars arcsec^-2. MICADO will be able to access the stellar content of the cores of all dense young stellar clusters in the Magellanic Clouds, allowing the peak and shape of the IMF to be studied in great detail outside the Milky Way. At a distance of 2 Mpc, all stars with M > 2 Msun will be resolved in fields of <10^4 stars arcsec^-2 , allowing the high-mass end of the IMF to be studied in all galaxies out to and including NGC300.
Since 2005 ESO has been working with its community and industry to develop an extremely large optical/infrared telescope. ESO's Extremely Large Telescope, or ELT for short, is a revolutionary ...ground-based telescope that will have a 39-metre main mirror and will be the largest visible and infrared light telescope in the world. To address specific topics that are needed for the science operations and calibrations of the telescope, thirteen specific working groups were created to coordinate the effort between ESO, the instrument consortia, and the wider community. We describe here the goals of these working groups as well as their achievements so far.
ScopeSim is a flexible multipurpose instrument data simulation framework built in Python. It enables both raw and reduced observation data to be simulated for a wide range of telescopes and ...instruments quickly and efficiently on a personal computer. The software is currently being used to generate simulated raw input data for developing the data reduction pipelines for the MICADO and METIS instruments at the ELT. The ScopeSim environment consists of three main packages which are responsible for providing on-sky target templates (ScopeSim_templates), the data to build the optical models of various telescopes and instruments (instrument reference database), and the simulation engine (ScopeSim). This strict division of responsibilities allows ScopeSim to be used to simulate observation data for many different instrument and telescope configurations for both imaging and spectroscopic instruments. ScopeSim has been built to avoid redundant calculations wherever possible. As such it is able to deliver simulated observations on time scales of seconds to minutes. All the code and data is open source and hosted on Github. The community is also most welcome, and indeed encouraged to contribute to code ideas, target templates, and instrument packages.
We design the imaging data calibration and reduction software for MICADO, the First Light near-IR instrument on the Extremely Large Telescope. In this process we have hit the limit of what can be ...achieved with a detailed software design that is primarily captured in pdf/word documents. Trade-offs between hardware and calibration software are required to meet stringent science requirements. To support such trade-offs, more software needs to be developed in the early phases of the project: simulators, archives, prototype recipes and pipelines. This requires continuous and efficient exchange of evolving designs between the software and hardware groups, which is hard to achieve with manually maintained documents. This, and maintaining the consistency between the design documents and various software components is possible with a machine readable version of the design. We construct a detailed design that is readable by both software and humans. From this the design documentation, prototype pipelines and data archives are generated automatically. We present the implementation of such an approach for the calibration software detailed design for the ELT MICADO imager which is based on expertise and lessons learned in earlier projects (e.g. OmegaCAM, MUSE, Euclid).
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