Search

SOXS (Son Of X-Shooter) is a single object spectrograph, characterized by offering a wide simultaneous spectral coverage from U- to H-band, built by an international consortium for the 3.6-m ESO New Technology Telescope at the La Silla Observatory, in the Southern part of the Chilean Atacama Desert. The consortium is focussed on a clear scientific goal: the spectrograph will observe all kind of transient and variable sources discovered by different surveys with a highly flexible schedule, updated daily, based on the Target of Opportunity concept. It will provide a key spectroscopic partner to any kind of imaging survey, becoming one of the premier transient follow-up instruments in the Southern hemisphere. SOXS will study a mixture of transients encompassing all distance scales and branches of astronomy, including fast alerts (such as gamma-ray bursts and gravitational waves), mid-term alerts (such as supernovae and X-ray transients), and fixed-time events (such as the close-by passage of a minor planet or exoplanets). It will also have the scope to observe active galactic nuclei and blazars, tidal disruption events, fast radio bursts, and more. Besides of the consortium programs on guaranteed time, the instrument is offered to the ESO community for any kind of astrophysical target. The project has passed the Final Design Review and is currently in manufacturing and integration phase. This paper describes the development status of the project., Proc SPIE Volume 11447, Ground-based and Airborne Instrumentation for Astronomy VIII, 1144709,2020

T Tauri has long been the prototypical young pre-main-sequence star. However, it has now been decomposed into a triple system with a complex disk and outflow geometry. We aim to measure the brightness of all three components of the T Tauri system (T Tau N, T Tau Sa, T Tau Sb) in the mid-infrared in order to obtain photometry around the $\sim 9.7~\mu m$ silicate feature. This allows us to study their variability and to investigate the distribution of dust and the geometry of circumstellar and circumbinary disks in this complex system. We observe T Tauri with the VLT/VISIR-NEAR instrument. With kernel phase interferometry post-processing of the data, and using the astrometric positions of all three components from VLT/SPHERE, we measure the three components' individual brightnesses (including the southern binary at an angular separation down to $\sim 0.2~\lambda/D$) and obtain their photometry. In order to validate our methods, we simulate and recover mock data of the T Tauri system using the observed reference point-spread function of HD 27639. We find that T Tau N is rather stable and shows weak silicate emission, while T Tau Sa is highly variable and shows prominent silicate absorption. T Tau Sb became significantly fainter compared to data from 2004 and 2006, suggesting increased extinction by dust. The precision of our photometry is limited by systematic errors, which is consistent with previous studies using kernel phase interferometry. Our results confirm the complex scenario of misaligned disks in the T Tauri system that had been observed previously, and they are in agreement with the recently observed dimming of T Tau Sb in the near-infrared. Our mid-infrared photometry supports the interpretation that T Tau Sb has moved behind the dense region of the Sa-Sb circumbinary disk on its tight orbit around Sa, therefore suffering increased extinction., Comment: 14 pages, 7 figures, accepted for publication in Astronomy & Astrophysics

SOXS (Son Of X-Shooter) will be a spectrograph for the ESO NTT telescope capable to cover the optical and NIR bands, based on the heritage of the X-Shooter at the ESO-VLT. SOXS will be built and run by an international consortium, carrying out rapid and longer term Target of Opportunity requests on a variety of astronomical objects. SOXS will observe all kind of transient and variable sources from different surveys. These will be a mixture of fast alerts (e.g. gamma-ray bursts, gravitational waves, neutrino events), mid-term alerts (e.g. supernovae, X-ray transients), fixed time events (e.g. close-by passage of minor bodies). While the focus is on transients and variables, still there is a wide range of other astrophysical targets and science topics that will benefit from SOXS. The design foresees a spectrograph with a Resolution-Slit product ~ 4500, capable of simultaneously observing over the entire band the complete spectral range from the U- to the H-band. The limiting magnitude of R~20 (1 hr at S/N~10) is suited to study transients identified from on-going imaging surveys. Light imaging capabilities in the optical band (grizy) are also envisaged to allow for multi-band photometry of the faintest transients. This paper outlines the status of the project, now in Final Design Phase., Comment: 12 pages, 14 figures, to be published in SPIE Proceedings 10702

The near-Earth asteroid (NEA) 2015 TB had a very close encounter with Earth at 1.3 lunar distances on October 31, 2015. We obtained 3-band mid-infrared observations of this asteroid with the ESO VLT-VISIR instrument covering approximately four hours in total. We also monitored the visual lightcurve during the close-encounter phase. The NEA has a (most likely) rotation period of 2.939 ± 0.005 h and the visual lightcurve shows a peak-to-peak amplitude of approximately 0.12 ± 0.02 mag. A second rotation period of 4.779 ± 0.012 h, with an amplitude of the Fourier fit of 0.10 ± 0.02 mag, also seems compatible with the available lightcurve measurements. We estimate a V-R colour of 0.56 ± 0.05 mag from different entries in the MPC database. A reliable determination of the object's absolute magnitude was not possible. Applying different phase relations to the available R-/V-band observations produced H = 18.6 mag (standard H-G calculations) or H = 19.2 mag and H = 19.8 mag (via the H-G procedure for sparse and low-quality data), with large uncertainties of approximately 1 mag. We performed a detailed thermophysical model analysis by using spherical and partially also ellipsoidal shape models. The thermal properties are best explained by an equator-on (± 30°) viewing geometry during our measurements with a thermal inertia in the range 250-700 J m s K (retrograde rotation) or above 500 J m s K (prograde rotation). We find that the NEA has a minimum size of approximately 625 m, a maximum size of just below 700 m, and a slightly elongated shape with a/b 1.1. The best match to all thermal measurements is found for: (i) thermal inertia Γ = 900 J m s K; D = 644 m, p = 5.5% (prograde rotation with 2.939 h); regolith grain sizes of 50-100 mm; (ii) thermal inertia Γ = 400 J m s K; D = 667 m, p = 5.1% (retrograde rotation with 2.939 h); regolith grain sizes of 10-20 mm. A near-Earth asteroid model (NEATM) confirms an object size well above 600 m (best NEATM solution at 690 m, beaming parameter η = 1.95), significantly larger than early estimates based on radar measurements. In general, a high-quality physical and thermal characterisation of a close-encounter object from two-week apparition data is not easily possible. We give recommendations for improved observing strategies for similar events in the future. © ESO, 2017., The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378. Funding from Spanish grant AYA-2014-56637-C2-1-P is acknowledged. Hungarian funding from the NKFIH grant GINOP-2.3.2-15-2016-00003 is also acknowledged. R.D. acknowledges the support of MINECO for his Ramon y Cajal Contract.

The article tries to provide a perspective summary of the planetary science to be performed with future extremely large telescopes (ELTs) as an outcome of the workshop on ‘Future Ground-based Solar System Research: Synergies between Space Probes and Space Telescopes’ held on 8–12 September 2008 in Portoferraio on Isola d’ Elba, Italy. It addresses science cases on solar system objects that might challenge the capabilities of ELTs and that provide a major step forward in the knowledge and understanding of planetary system objects per se and all populations. We also compile high-level requirements for such telescopes and their instrumentation that should enable successful ELT usage for research on objects in the Solar System, the ‘disturbing foreground to real astronomy’.

Aims. Near diffraction-limited images have been taken at 8.9, 11.9, and 12.9 micron for the brightest extragalactic sources in the southern sky, in order to optimally plan N-band observations with MIDI (MID-infrared Interferometric instrument) at the VLTI. Methods. We have assembled a sample of 21 objects consisting of all the AGNs observable from Paranal observatory, Chile, plus three non-AGN objects, with an estimated N-band flux greater than 400mJy. We used the TIMMI2 Mid Infrared instrument mounted on the ESO's 3.6m telescope to obtain near diffraction-limited images in order to establish the unresolved core flux within < 0.5 arscsec. Results. Positions and core total fluxes were obtained for all sources in our sample and compared with similar investigations in the literature. We find that 15 AGN and the nuclear starburst in NGC 253 exhibit an unresolved core flux < 300mJy at 11.9 micron, making them promising targets for MIDI at the VLTI. For extended sources, near diffraction-limited images are presented and discussed.

We present the characteristics of the dust comae of two comets, 126P/IRAS, a member of the Halley family (a near-isotropic comet), and 2P/Encke, an ecliptic comet. We have primarily used mid- and far-infrared data obtained by the ISOPHOT instrument aboard the Infrared Space Observatory (ISO) in 1996 and 1997, and mid-infrared data obtained by the SPIRIT III instrument aboard the Midcourse Space Experiment (MSX) in 1996. We find that the dust grains emitted by the two comets have markedly different thermal and physical properties. P/IRAS's dust grain size distribution appears to be similar to that of fellow family member 1P/Halley, with grains smaller than 5 microns dominating by surface area, whereas P/Encke emits a much higher fraction of big (20 μm and higher) grains, with the grain mass distribution being similar to that which is inferred for the interplanetary dust population. P/Encke's dearth of micron-scale grains accounts for its visible-wavelength classification as a “gassy” comet. These conclusions are based on analyses of both imaging and spectrophotometry of the two comets; this combination provides a powerful way to constrain cometary dust properties. Specifically, P/IRAS was observed preperihelion while 1.71 AU from the Sun, and seen to have a 15-arcmin long mid-infrared dust tail pointing in the antisolar direction. No sunward spike was seen despite the vantage point being nearly in the comet's orbital plane. The tail's total mass at the time was about 8×109 kg. The spectral energy distribution (SED) is best fit by a modified greybody with temperature T=265±15 K and emissivity e proportional to a steep power law in wavelength λ: e∝λ−α, where α=0.50±0.20 (2σ) . This temperature is elevated with respect to the expected equilibrium temperature for this heliocentric distance. The dust mass loss rate was between 150–600 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 3.3, and the albedo of the dust was 0.15±0.03. Carbonaceous material is depleted in the comet's dust by a factor of 2–3, paralleling the C2 depletion in P/IRAS's gas coma. P/Encke, on the other hand, observed while 1.17 AU from the Sun, had an SED that is best fit by a Planck function with T=270±15 K and no emissivity falloff. The dust mass loss rate was 70–280 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 2.3, and the albedo of the dust was about 0.06±0.02. These conclusions are consistent with the strongly curved dust tail and bright dust trail seen by Reach et al. (2000; Icarus 148, 80) in their ISO 12-μm imaging of P/Encke. The observed differences in the P/IRAS and P/Encke dust are most likely due to the less evolved and insolated state of the P/IRAS nuclear surface. If the dust emission behavior of P/Encke is typical of other ecliptic comets, then comets are the major supplier of the interplanetary dust cloud.

We report on high-resolution and spatially-resolved spectra of Io in the 4.0 {\mu}m region, recorded with the VLT/CRIRES instrument in 2008 and 2010, which provide the first detection of the {\nu}1 + {\nu}3 band of SO2 in Io's atmosphere. Data are analyzed to constrain the latitudinal, longitudinal, and diurnal distribution of Io's SO2 atmosphere as well as its characteristic temperature. equatorial SO2 column densities clearly show longitudinal asymmetry, but with a maximum of around 1.5e17 cm-2 at central meridian longitude L = 200-220 and a minimum of around 3e16 cm-2 at L = 285-300, the longitudinal pattern somewhat differs from earlier inferences from Ly {\alpha} and thermal IR measurements. Within the accuracy of the measurements, no evolution of the atmospheric density from mid-2008 to mid-2010 can be distinguished. The decrease of the SO2 column density towards high latitude is apparent, and the typical latitudinal extent of the atmosphere found to be (+-) 40{\deg} at half-maximum. The data show moderate diurnal variations of the equatorial atmosphere, which is evidence for a partially sublimation-supported atmospheric component. Compared to local noon, factor of 2 lower densities are observed around 40{\deg} before and 80{\deg} after noon. Best-fit gas temperatures range from 150 to 220 K, with a weighted mean value of 170 (+-) 20 K, which should represent the column-weighted mean kinetic temperature of Io's atmosphere. Finally, although the data include clear thermal emission due to Pillan (in outburst in July 2008) and Loki, no detectable enhancements in the SO2 atmosphere above these volcanic regions are found, with an upper limit of 4e16 cm-2 at Pillan and 1e17 cm-2 at Loki., Comment: Accepted for publication in Icarus

The ESO VLT with its suite of infrared instruments (e.g. ISAAC, VISIR) allows for an area-limited deep survey for infrared-bright point sources in nearby local group galaxies. Data in four colours can be collected: 3, 5, 10, and 20μm; the 10/20μm data can be complemented with TIMMI2, a new instrument presently under construction for ESO's 3.6m telescope on La Silla. The scientific result will be a complete catalogue of obscured Asymptotic Giant Branch Stars in the LMC, the SMC and the Sagittarius Dwarf Galaxy (SDG). Using mostly twilight time, such a survey can be done for an area of ≈ 100 □arcmin per year per galaxy. At 10μm the limiting flux is expected to be 2–3 orders of magnitude fainter than the IRAS point source catalogue. This catalogue would give the first coherent sample of AGB stars with precise distances and consequently absolute bolometric luminosities. It may lead to a substantially better understanding of the mass loss of AGB stars, an important, but as of today largely enigmatic phase of stellar evolution. As a byproduct many more IR-bright objects in the Magellanic Clouds, e.g. dust envelopes around normal stars, luminous blue variable stars (LBV) or compact obscured HII-regions, will be discovered. For the SDG no LBVs or YSOs are expected as it had no star formation for the past 5 Gyr.

The distribution of the thermal infrared radiation from dust in the inner coma of comet Hale-Bopp (1995 O1), based on observations obtained at ESO, LaSilla, Chile, has been mapped in the 10-/μm atmospheric window on July 16, 1997. A preliminary analysis of the infrared data taken with a resolution of 0.498 arcsec per pixel shows a heterogeneous distribution of the infrared radiation in the inner coma. Three asymmetric brightness peaks (in addition to the nucleus) are apparent. Similar behaviour of the distribution of the infrared brightness was found on all observed spectral bands centered around 8.39 μm, 9.78 μm, 11.65 μm, and 12.56 μm. The spectral energy distribution is compared to black-body curves. The observed distribution of the infrared brightness close to the nucleus could be interpreted by multiple sources of ejected dust particles. Simulated aperture photometry shows only minor deviation from a simple spherically symmetric outflow model.

TIMMI stands for Thermal Infrared Multi Mode Instrument. TIMMI allows for imaging (at present 16 filters available) with variable magnifications as well as limited long-slit spectroscopy in the l0 μm atmospheric window. The instrument was built by the Service d'Astrophysique (SAP) according to ESO's specification in a period of 2 years. At the telescope the instrument is using the ƒ35 chopping configuration in conjunction with the special adaptor unit. TIMMI control and primary data-acquisition is performed by an VME-based computer (under OS9) while final data storage and online data processing with ESO's image processing system MIDAS is done using an UNIX workstation. While TIMMI will provide new observational possibilities for the ESO users community it is also supposed to become a test-bed to gain experience for similar instrumentation at the VLT.

The book summarises the key science cases for the E-ELT. This Science Case summary was prepared at the end of 2009 with the help of: the E-ELT Science Working Group who prepared the Design Reference Mission; close to 200 PIs from the community that submitted cases to the Design Reference Science Plan; Instrument Science Teams from ~40 institutes that developed science cases for the ten phase A studies for instruments; the E-ELT Science Office team at ESO, that developed the Exposure Time Calculators and ran a large number of detailed performance simulations.

VISIR is the VLT mid-infrared (mid-IR) Imager and Spectrometer. It provides data at high spatial and spectral resolution in the N (8–13 μm) and Q (16–20 μm) atmospheric windows. VISIR observations have provided unique constraints on targets such as central regions of AGNs, or protoplanetary disks. Its successor on an ELT will provide data with unique spatial resolution (0.05 arcsec) and competitive sensitivity (50 μJy sources detectable in 1 hour), thus allowing e.g. to better characterize exoplanetary disks and exoplanets. We review here a selection of scientific contributions thanks to VISIR and then, in the light of the VISIR experience, we discuss the stakes for a mid-IR instrument at the European ELT.

A spectral analysis of the fluctuations of the infrared sky radiance at λ ≈ 10μm was made at the ESO-site of La Silla in Northern Chile. The data are compared to literature. The consequences of the results on infrared observing for future large telescopes are discussed: our data suggest that in order to achieve background noise limited performance in the 10μm atmospheric window chopping with frequencies of ≈8 Hz and amplitudes of ≈10 arcsec is mandatory.

While silicon can be easily etched anisotropically using a KOH solution, the anisotropic etching of germanium is difficult to achieve. We describe experiments using different etchants and different masking layers. The best technological results are obtained using a solution of phosphoric acid and hydrogen peroxide . As a mask, a thin film of chromium is preferable. The slow-etching plane is the plane. At , the etch rate is . With this technology it is possible to fabricate V grooves and the other typical structures of anisotropic etching known from silicon technology. One possible application is the production of infrared optical devices in germanium.

A variety of compact nebulae was observed to retrieve the morphology in the light of infrared recombination lines ([SIV] at λ = 10.5 μm and [NeII] at λ = 12.8μm) using TIMMI, ESO’s focal reducer for the thermal infrared at the 3.6m telescope (Kaufl et al. 1994). Compared to optical images in some cases striking differences are found. It should be noted that the dust in nearly all PNs is transparent at λ ≈ 10μm even if there is substantial extinction in the optical (λ ≤ 1μm). As compared to space based infrared platforms (IRAS and ISO) our observations have lower sensitivity but sub-arcsec spatial resolution. In some cases the data allow also to assess the relative spatial distribution of dust and gas.

Mass loss on the AGB is extremely important for galactic chemical evolution but is poorly understood. A data set of a coherently selected sample of AGB stars is required to resolve this issue. The VLT with its suite of infrared instruments allows the Large Magellanic Cloud, the Small Magellanic Cloud and the Galactic Center to be completely surveyed for AGB stars. The survey could be done using only morning and evening twilight, which is of no use to other programs. The limiting flux for this survey is expected to be 2–3 orders of magnitude fainter than that of the IRAS 12.5 μm channel. The survey will result in the first complete catalog of AGB stars at a known distance. The objects would then be studied more in depth, employing high spatial resolution IR imaging and medium to high resolution spectroscopy with a special emphasis on rotational-vibrational molecular transitions. This program could lead to an understanding of this important but as yet enigmatic phase of stellar evolution, especially the physics of mass loss and the thermonuclear evolution of AGB stellar cores.

Since 1984, the CEA-LETI-LIR (Infrared Laboratory) has been involved in development of Si:Ga/DRO hybrid detector arrays dedicated to imaging of astronomical sources in the 8–13 µm range. Successively, 32×32 element arrays were successfully manufactured for the ISOCAM camera and 64×64 arrays were fabricated for ground-based imaging. The latter detectors have been integrated in 3 cameras (C10µ, CAMIRAS and TIMMI for ESO) and have led to excellent astrophysical results since 1990.

Context. The direct imaging of rocky exoplanets is one of the major science goals of upcoming large telescopes. The contrast requirement for imaging such planets is challenging. However, the mid-IR (infrared) regime provides the optimum contrast to directly detect the thermal signatures of exoplanets in our solar neighbourhood. Aims. We aim to exploit novel fast-chopping techniques newly developed for astronomy with the aid of adaptive optics to look for thermal signatures of exoplanets around bright stars in the solar neighbourhood. Methods. We used the upgraded Very Large Telescope Imager and Spectrometer for the mid-InfraRed (VISIR) instrument with high-contrast imaging capability optimised for observations at 10 μm to look for exoplanets around five nearby (d < 4 pc) stars. The instrument provides an improved signal-to-noise ratio (S/N) by a factor of ~4 in the N-band compared to standard VISIR for a given S/N and time. Results. In this work, we achieve a detection sensitivity of sub-mJy, which is sufficient to detect a few Jupiter mass planets in nearby systems. Although no detections are made, we achieve most sensitive limits within ϵ Indi A and ϵ Eri, we achieve detection limits very close to the giant planets discovered by RV, with the limits on ϵ Indi A being the most sensitive to date. Our non-detection therefore supports an older age for ϵ Indi A. The results presented here are promising for high-contrast imaging and exoplanet detections in the mid-IR regime.