Astronomy's Next-Generation
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Biosignatures Search in Habitable Planets
galaxies Review Biosignatures Search in Habitable Planets Riccardo Claudi 1,* and Eleonora Alei 1,2 1 INAF-Astronomical Observatory of Padova, Vicolo Osservatorio, 5, 35122 Padova, Italy 2 Physics and Astronomy Department, Padova University, 35131 Padova, Italy * Correspondence: [email protected] Received: 2 August 2019; Accepted: 25 September 2019; Published: 29 September 2019 Abstract: The search for life has had a new enthusiastic restart in the last two decades thanks to the large number of new worlds discovered. The about 4100 exoplanets found so far, show a large diversity of planets, from hot giants to rocky planets orbiting small and cold stars. Most of them are very different from those of the Solar System and one of the striking case is that of the super-Earths, rocky planets with masses ranging between 1 and 10 M⊕ with dimensions up to twice those of Earth. In the right environment, these planets could be the cradle of alien life that could modify the chemical composition of their atmospheres. So, the search for life signatures requires as the first step the knowledge of planet atmospheres, the main objective of future exoplanetary space explorations. Indeed, the quest for the determination of the chemical composition of those planetary atmospheres rises also more general interest than that given by the mere directory of the atmospheric compounds. It opens out to the more general speculation on what such detection might tell us about the presence of life on those planets. As, for now, we have only one example of life in the universe, we are bound to study terrestrial organisms to assess possibilities of life on other planets and guide our search for possible extinct or extant life on other planetary bodies. -
8. Adaptive Optics 299
8. Adaptive Optics 299 8.1 Introduction Adaptive Optics is absolutely essential for OWL, to concentrate the light for spectroscopy and imaging and to reach the diffraction limit on-axis or over an extended FoV. In this section we present a progressive implementation plan based on three generation of Adaptive Optics systems and, to the possible extent, the corresponding expected performance. The 1st generation AO − Single Conjugate, Ground Layer, and distributed Multi-object AO − is essentially based on Natural Guide Stars (NGSs) and makes use of the M6 Adaptive Mirror included in the Telescope optical path. The 2nd generation AO is also based on NGSs but includes a second deformable mirror (M5) conjugated at 7-8 km – Multi-Conjugate Adaptive Optics − or a post focus mirror conjugated to the telescope pupil with a much higher density of actuators -tweeter- in the case of EPICS. The 3rd generation AO makes use of single or multiple Laser Guide Stars, preferably Sodium LGSs, and should provide higher sky coverage, better Strehl ratio and correction at shorter wavelengths. More emphasis in the future will be given to the LGS assisted AO systems after having studied, simulated and demonstrated the feasibility of the proposed concepts. The performance presented for the AO systems is based on advances from today's technology in areas where we feel confident that such advances will occur (e.g. the sizes of the deformable mirrors). Even better performance could be achieved if other technologies advance at the same rate as in the past (e.g. the density of actuators for deformable mirrors). -
The Thirty-Meter Telescope: Science and Instrumentation for a Next-Generation Observatory
J. Astrophys. Astr. (2013) 34, 97–120 c Indian Academy of Sciences The Thirty-Meter Telescope: Science and Instrumentation for a Next-Generation Observatory Luc Simard TMT Observatory Corporation, 1111 South Arroyo Parkway, Suite 200, Pasadena, CA 91105, USA. e-mail: [email protected] Received 15 March 2013; accepted 25 June 2013 Abstract. The Thirty-Meter Telescope international observatory will enable transformational observations over the full cosmic timeline all the way from the first luminous objects in the Universe to the plan- ets and moons of our own solar system. To realize its full scientific potential, TMT will be equipped with a powerful suite of adaptive optics systems and science instruments. Three science instruments will be available at first light: an optical multi-object spectrometer, a near- infrared multi-slit spectrometer and a diffraction-limited near-infrared imager and integral field spectrometer. In addition to these three instru- ments, a diverse set of new instruments under study will bring additional workhorse capabilities to serve the science interests of a broad user community. The development of TMT instruments represents a large, long-term program that offers a wide range of opportunities to all TMT partners. Key words.Telescopes—instrumentation: spectrographs—instrumentation: photometers. 1. Introduction The Thirty-Meter Telescope (TMT) will be a flagship facility for addressing many compelling areas in astrophysics and delivering currently unforeseen discoveries in astronomy. TMT will lead a new generation of giant optical/infra-red, ground- based telescopes with fully integrated Adaptive Optics (AO). An overview of the TMT Observatory is given in Sanders (2013), and the TMT Adaptive Optics pro- gram is described in Ellerbroek (2013). -
The Infrared Imaging Spectrograph (IRIS) for TMT: Instrument Overview
The Infrared Imaging Spectrograph (IRIS) for TMT: Instrument Overview Anna M. Moore*a, James E. Larkinb, Shelley A. Wrightc,d, Brian Baumane, Jennifer Dunnf, Brent Ellerbroekg, Andrew C. Phillipsh, Luc Simardi, Ryuji Suzukij, Kai Zhangk, Ted Aliadob, George Brimsb, John Canfieldb, Shaojie Chenc, Richard Dekanya, Alex Delacroixa, Tuan Doc,d, Glen Herriotf, Bungo Ikenouej, Chris Johnsonb, Elliot Meyerc,d, Yoshiyuki Obuchij, John Pazderf, Vladimir Reshetovf, Reed Riddlea, Sakae Saitoj, Roger Smitha, Ji Man Sohnb, Fumihiro Uraguchij, Tomonori Usudaj, Eric Wangb, Lianqi Wangg, Jason Weissj and Robert Woofff aCaltech Optical Observatories,1200 E California Blvd., Pasadena, CA 91125; bDepartment of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547; cDunlap Institute for Astronomy & Astrophysics, University of Toronto, ON, Canada, M5S 3H4; dDepartment of Astronomy & Astrophysics, University of Toronto, ON, Canada, M5S 3H4; eLawrence Livermore National Laboratory, 7000 East Ave., M/S L-210, Livermore, CA 94550; fHerzberg Institute of Astrophysics (HIA), National Research Council Canada, 5071 W Saanich Rd, Victoria, V9E 2E7; gThirty Meter Telescope Observatory Corporation, 1111 S. Arroyo Pkwy, #200, Pasadena, CA 91105; hUniversity of California Observatories, CfAO, University of California, 1156 High St., Santa Cruz, CA 95064; iDominion Astrophysical Observatory, National Research Council Canada, W Saanich Rd, Victoria, V9E 2E7; jNational Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 Japan; kNanjing Institute of Astronomical Optics and Technology, Chinese Academy of Sciences, 188 Bancang St, Nanjing, Jiangsu, China 210042. ABSTRACT We present an overview of the design of IRIS, an infrared (0.84 - 2.4 micron) integral field spectrograph and imaging camera for the Thirty Meter Telescope (TMT). -
India's Participation in the Thirty-Meter Telescope Project B
J. Astrophys. Astr. (2013) 34, 87–95 c Indian Academy of Sciences India’s Participation in the Thirty-Meter Telescope Project B. Eswar Reddy Indian Institute of Astrophysics, Koramangala, Bangalore 560 034, India e-mail: [email protected] Received 30 April 2013; accepted 26 June 2013 Abstract. In 2010, the Department of Science and Technology (DST), Govt. of India, approved astronomers’ proposal of India joining the inter- national consortium of the USA, Japan, Canada and China to build and operate the next generation mega ground based optical and infrared tele- scope known as the Thirty-Meter Telescope (TMT) after its aperture size of 30-meter diameter. Since then, India is engaged in many aspects of the TMT project, both at technical and policy levels. In this article, I con- fine to the description of India’s efforts leading up to the decision to join the consortium, and the progress made since then with respect to India’s technical contributions to the project. Key words. Telescope: thirty-meter telescope—India TMT: India TMT Co-ordination Center. 1. Background The quest for understanding fundamental issues such as the possible existence of life beyond the solar system, the so-called dark energy believed to be causing the Uni- verse to accelerate, and many other astrophysical phenomenon such as formation of planetary systems, and formation and evolution of stars and galaxies led astronomers the world over to propose to build the next generation mega ground-based optical and infrared telescopes. Thus formed the three independent international consortia consisting of countries and institutes cutting across the continents: The Giant Magel- lan Telescope (25-m; GMT, site: Las Campanas, Chile), the Thirty-Meter Telescope (30-m; TMT, site: Mauna Kea, Hawaii, USA) and the European-Extremely Large Telescope (39-m; E-ELT, site: Cerro Armazons, Chile). -
Subaru Super Deep Field (SSDF) with AO
Subaru Super Deep Field (SSDF) using Adaptive Optics Yosuke Minowa (NAOJ) on behalf of Yoshii, Y. (IoA, Univ. of Tokyo; PI) and SSDF team: Kobayashi, N. (IoA, Univ. of Tokyo), Totani, T. (Kyoto Univ.), Takami, H., Takato, N. Hayano, Y., Iye, M. (NAOJ). Subaru UM (1/30/2007) SSDF project: What? { Scientific motivation 1. Study the galaxy population at the unprecedented faint end (K’=23-25mag) to find any new population which may explain the missing counterpart to the extragalactic background light. 2. Study the morphological evolution of field galaxies in rest-frame optical wavelengths to find the origin of Hubble sequence. Æ high-resolution deep imaging of distant galaxies SSDF project: How? { Deep imaging of high-z galaxies with AO. z Improve detection sensitivity. Peak intensity: with AO ~ 10-20 times higher 0”.07 without AO z Improve spatial 0”.4 resolution FWHM < 0”.1 AO is best suited for the deep imaging study of high-z galaxies which requires both high-sensitivity and high-resolution. z SSDF project: Where? { Target field: a part of “Subaru Deep Field” (SDF) z Originally selected to locate near a bright star for AO observations (Maihara+01). z Optical~NIR deep imaging data are publicly available. { Enable the SED fitting of detected galaxies. Æ phot-z, rest-frame color, (Maihara+01) stellar mass… Observations { AO36+IRCS at Cassegrain z K’-band (2.12um) imaging with 58mas mode z providing 1x1 arcmin2 FOV AO36 IRCS To achieve unprecedented faint-end, we concentrated on K’-band imaging of this 1arcmin2 field, rather than wide-field or multi-color imaging. -
Modern Astronomical Optics 1
Modern Astronomical Optics 1. Fundamental of Astronomical Imaging Systems OUTLINE: A few key fundamental concepts used in this course: Light detection: Photon noise Diffraction: Diffraction by an aperture, diffraction limit Spatial sampling Earth's atmosphere: every ground-based telescope's first optical element Effects for imaging (transmission, emission, distortion and scattering) and quick overview of impact on optical design of telescopes and instruments Geometrical optics: Pupil and focal plane, Lagrange invariant Astronomical measurements & important characteristics of astronomical imaging systems: Collecting area and throughput (sensitivity) flux units in astronomy Angular resolution Field of View (FOV) Time domain astronomy Spectral resolution Polarimetric measurement Astrometry Light detection: Photon noise Poisson noise Photon detection of a source of constant flux F. Mean # of photon in a unit dt = F dt. Probability to detect a photon in a unit of time is independent of when last photon was detected→ photon arrival times follows Poisson distribution Probability of detecting n photon given expected number of detection x (= F dt): f(n,x) = xne-x/(n!) x = mean value of f = variance of f Signal to noise ration (SNR) and measurement uncertainties SNR is a measure of how good a detection is, and can be converted into probability of detection, degree of confidence Signal = # of photon detected Noise (std deviation) = Poisson noise + additional instrumental noises (+ noise(s) due to unknown nature of object observed) Simplest case (often -
Adaptive Optics: an Introduction Claire E
1 Adaptive Optics: An Introduction Claire E. Max I. BRIEF OVERVIEW OF ADAPTIVE OPTICS Adaptive optics is a technology that removes aberrations from optical systems, through use of one or more deformable mirrors which change their shape to compensate for the aberrations. In the case of adaptive optics (hereafter AO) for ground-based telescopes, the main application is to remove image blurring due to turbulence in the Earth's atmosphere, so that telescopes on the ground can "see" as clearly as if they were in space. Of course space telescopes have the great advantage that they can obtain images and spectra at wavelengths that are not transmitted by the atmosphere. This has been exploited to great effect in ultra-violet bands, at near-infrared wavelengths that are not in the atmospheric "windows" at J, H, and K bands, and for the mid- and far-infrared. However since it is much more difficult and expensive to launch the largest telescopes into space instead of building them on the ground, a very fruitful synergy has emerged in which images and low-resolution spectra obtained with space telescopes such as HST are followed up by adaptive- optics-equipped ground-based telescopes with larger collecting area. Astronomy is by no means the only application for adaptive optics. Beginning in the late 1990's, AO has been applied with great success to imaging the living human retina (Porter 2006). Many of the most powerful lasers are using AO to correct for thermal distortions in their optics. Recently AO has been applied to biological microscopy and deep-tissue imaging (Kubby 2012). -
A Review of Astronomical Science with Visible Light Adaptive Optics
A review of astronomical science with visible light adaptive optics Item Type Article Authors Close, Laird M. Citation Laird M. Close " A review of astronomical science with visible light adaptive optics ", Proc. SPIE 9909, Adaptive Optics Systems V, 99091E (July 26, 2016); doi:10.1117/12.2234024; http:// dx.doi.org/10.1117/12.2234024 DOI 10.1117/12.2234024 Publisher SPIE-INT SOC OPTICAL ENGINEERING Journal ADAPTIVE OPTICS SYSTEMS V Rights © 2016 SPIE. Download date 30/09/2021 19:37:34 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/622010 Invited Paper A Review of Astronomical Science with Visible Light Adaptive Optics Laird M. Close1a, aCAAO, Steward Observatory, University of Arizona, Tucson AZ 85721, USA; ABSTRACT We review astronomical results in the visible (λ<1μm) with adaptive optics. Other than a brief period in the early 1990s, there has been little (<1 paper/yr) night-time astronomical science published with AO in the visible from 2000-2013 (outside of the solar or Space Surveillance Astronomy communities where visible AO is the norm, but not the topic of this invited review). However, since mid-2013 there has been a rapid increase visible AO with over 50 refereed science papers published in just ~2.5 years (visible AO is experiencing a rapid growth rate very similar to that of NIR AO science from 1997-2000; Close 2000). Currently the most productive small (D < 2 m) visible light AO telescope is the UV-LGS Robo-AO system (Baranec, et al. -
Adaptive Optics
Adaptive Optics Ruobing Dong Large portion is adopted from Claire Max’s lecture in UCSC 03/30/2011 Why is adaptive optics needed? Turbulence in earth’s atmosphere makes stars twinkle More importantly, turbulence spreads out light; makes it a blob rather than a point Even the largest ground-based astronomical telescopes have no better resolution than an 8" telescope Atmospheric perturbations cause distorted wavefronts Rays not Patten changes parallel at time scale of ~10ms each small parallel beam makes a Index of diffraction limited Plane spot on the image refraction Distorted plane Wave variations Wavefront Characterize turbulence strength by quantity r0 Wavefront of light r0 Primary mirror of telescope • “Coherence Length” r0 : Diameter of the circular pupil for which the diffraction limited image and the seeing limited image have the same angular resolution. (r0 ~ 15 - 30 cm at good observing sites • Pupil larger than r0, images are seeing dominated. Real time sequence from a A much larger small telescope with telescope, aperture aperture the size of r0 contains many r0 Schematic of adaptive optics system Feedback loop: next cycle corrects the (small) errors of the last cycle How does adaptive optics help? (cartoon approximation) Adaptive optics increases peak intensity of a point source Lick Observatory" No AO" With AO" Intensity" No AO" With AO" AO produces point spread functions with a “core” and “halo” Definition of “Strehl”: Ratio of peak intensity to that of “perfect” optical system" " Intensity x" When AO system performs well, -
What Is Adaptive Optics ?
6. Adaptive Optics Introduction to Adaptive Optics Brief introduction to adaptive optics: why, how ? AO for high contrast imaging Components of an AO system Types of AO systems Atmospheric Turbulence Useful references: Adaptive Optics in Astronomy (2004), by Francois Roddier (Editor), Cambridge University Press Adaptive Optics for Astronomical Telescopes (1998), by John W. Hardy, Oxford University Press 1 Why Adaptive Optics ? Gains offered by AO : Angular resolution: Resolve small features on Sun, Moon, planets, disks, galaxies Improved sensitivity for faint objects: Detection of faint objects is a background-limited problem. By making the image smaller, the AO system limits amount of background mixed with image, and improves sensitivity. Efficiency with AO goes as D4 instead of D2 without AO. This is especially important in infrared, as sky glows, and AO work well. Astrometry: Measuring the position of a source. For example: measuring the mass of the black hole in the center of our galaxy. Confusion limit: Astronomical imaging of sources is often confusion limited. Better angular resolution helps ! For example: studying stellar populations in nearby galaxies. High contrast imaging (Extreme-AO) 2 Direct imaging of exoplanets and disks What is Adaptive Optics ? Atmospheric turbulence limits size of images to ~1” (1/3600 of a degree) Diffraction limit of large telescopes is 0.1” to 0.01” → 10x to 100x smaller ! With AO Without AO AO uses a deformable mirror to correct atmospheric turbulence 3 Wavefront control for High contrast imaging -
A Status Report on the Thirty Meter Telescope Adaptive Optics Program
J. Astrophys. Astr. (2013) 34, 121–139 c Indian Academy of Sciences A Status Report on the Thirty Meter Telescope Adaptive Optics Program B. L. Ellerbroek TMT Observatory Corporation, 1111 S. Arroyo Pkwy., Ste. 200, Pasadena, CA 91107, USA. e-mail: [email protected] Received 15 March 2013; accepted 24 May 2013 Abstract. We provide an update on the recent development of the adap- tive optics (AO) systems for the Thirty Meter Telescope (TMT) since mid-2011. The first light AO facility for TMT consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). This order 60 × 60 laser guide star (LGS) multi- conjugate AO (MCAO) architecture will provide uniform, diffraction- limited performance in the J, H and K bands over 17–30 arcsec diameter fields with 50 per cent sky coverage at the galactic pole, as is required to support TMT science cases. The NFIRAOS and LGSF subsystems completed successful preliminary and conceptual design reviews, respec- tively, in the latter part of 2011. We also report on progress in AO component prototyping, control algorithm development, and system per- formance analysis, and conclude with an outline of some possible future AO systems for TMT. Key words. Adaptive optics—extremely large telescope. 1. Introduction The first light facility AO system for TMT is the Narrow Field Infra-Red AO Sys- tem (NFIRAOS), which will provide diffraction-limited performance in the J, H and K bands over 17–30 arcsec diameter fields with 50 per cent sky coverage at the galactic pole. This is accomplished with order 60 × 60 wavefront sensing and cor- rection, two deformable mirrors (DMs) conjugate to ranges of 0 and 11.2 km, six sodium Laser Guide Stars (LGSs) in an asterism with a diameter of 70 arcsec, and three low order (tip/tilt or tip/tilt/focus), infra-red Natural Guide Star (NGS) Wave- Front Sensors (WFSs) deployable within a 2 arcminute diameter patrol field.