[en] The direct detection of exoplanets and circumstellar disks is currently limited by a combination of high contrast and small angular separation. At the scale of single telescopes, these limitations are fought with coronagraphs, which remove the diffracted light from the central source. To obtain similar benefits with interferometry, one must employ specialized beam-combiners called interferometric nullers. Nullers discard the on-axis light and part of the astrophysical information to optimize the recording of light present in the dark fringe of the central source, which may contain light from circumstellar sources of interest. Asgard/NOTT will deploy an advanced beam-combination scheme offering favorable instrumental noise characteristics when the inputs are phased appropriately, although this tuning will require a specific strategy to overcome the resulting degeneracy. Furthermore, this must bring the phase of the incoming light to a good accuracy across the usable spectrum. Since the fringe-tracker operates at different wavelengths, it can only sense part of the offending errors, and we discuss the measurement of these errors with the science detector. NOTT operates in the L band and suffers from various effects such as water vapor, which has already been experienced with N-band nullers (Keck Interferometer Nuller, Large Binocular Telescope Interferometer). This effect can be corrected with prisms forming a variable thickness of glass and an adjustment of air optical path. Moreover, observations in the L band suffer from an additional and important chromatic effect due to longitudinal atmospheric dispersion coming from a resonance of carbon dioxide at 4.3μm that is impractical to correct with glass plates because of its non-linear wavelength dependency. To compensate for this effect efficiently, a novel type of compensation device will be deployed leveraging a gas cell of variable length at ambient pressure. After reviewing the impact of water vapor and CO<SUB>2</SUB>, we present the design of this atmospheric dispersion compensation device for Asgard/NOTT and describe a strategy to maintain this tuning on-sky.
Research Center/Unit :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Laugier, Romain; Katholieke University of Leuven, Belgium
Defrère, Denis; Katholieke University of Leuven, Belgium
Ireland, Michael; Australian National University, Canberra
Garreau, Germain; Katholieke University of Leuven, Belgium
Absil, Olivier ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO)
Matter, Alexis; Observatoire de la Cote d'Azur, France
Petrov, Romain; Observatoire de la Cote d'Azur, France
Berio, Philippe; Observatoire de la Cote d'Azur, France
Tuthill, Peter; University of Sydney, Australia
Labadie, Lucas; Andreas Eckart University of Cologne, Germany
Martinod, Marc-Antoine; Katholieke University of Leuven, Belgium
Language :
English
Title :
Asgard/NOTT: water vapor and CO<SUB>2</SUB> atmospheric dispersion compensation system
ERC - European Research Council F.R.S.-FNRS - Fonds de la Recherche Scientifique European Union
Commentary :
Copyright 2024 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. https://www.spiedigitallibrary.org/conference-proceedings-of-spie/13095/3018150/Asgard-NOTT--water-vapor-and-CO2-atmospheric-dispersion-compensation/10.1117/12.3018150.short
Colavita, M. M., Swain, M. R., Akeson, R. L., Koresko, C. D., and Hill, R. J., “Effects of Atmospheric Water Vapor on Infrared Interferometry,” Publications of the Astronomical Society of the Pacific 116(823), 876-885 (2004).
Koresko, C., Colavita, M. M., Serabyn, E., Booth, A., and Garcia, J., “Water vapor measurement and compensation in the near- and mid-infrared with the Keck Interferometer Nuller,” Advances in Stellar Interferometry 6268(818), 626817 (2006).
Defrère, D., Hinz, P., Downey, E., Ashby, D., Bailey, V., Brusa, G., Christou, J., Danchi, W. C., Grenz, P., Hill, J. M., Hoffmann, W. F., Leisenring, J., Lozi, J., McMahon, T., Mennesson, B., Millan-Gabet, R., Montoya, M., Powell, K., Skemer, A., Vaitheeswaran, V., Vaz, A., and Veillet, C., “Co-phasing the Large Binocular Telescope: Status and performance of LBTI/PHASECam,” 9146, 914609 (July 2014).
Kendrew, S., Jolissaint, L., Mathar, R. J., Stuik, R., Hippler, S., and Brandl, B., “Atmospheric refractivity effects on mid-infrared ELT adaptive optics,” 7015, 70155T (July 2008).
Absil, O., Delacroix, C., de Xivry, G. O., Pathak, P., Willson, M., Berio, P., van Boekel, R., Matter, A., Defrere, D., Burtscher, L., Woillez, J., and Brandl, B., “Impact of water vapor seeing on mid-infrared high-contrast imaging at ELT scale,” 13 (2022).
Defrère, D., Absil, O., Berger, J. P., Boulet, T., Danchi, W. C., Ertel, S., Gallenne, A., Hénault, F., Hinz, P., Huby, E., Ireland, M., Kraus, S., Labadie, L., Le Bouquin, J. B., Martin, G., Matter, A., Mérand, A., Mennesson, B., Minardi, S., Monnier, J. D., Norris, B., de Xivry, G. O., Pedretti, E., Pott, J. U., Reggiani, M., Serabyn, E., Surdej, J., Tristram, K. R., and Woillez, J., “The path towards high-contrast imaging with the VLTI: The Hi-5 project,” Experimental Astronomy 46(3), 475-495 (2018).
Defrère, D., Bigioli, A., Dandumont, C., Garreau, G., Laugier, R., Martinod, M.-A., Absil, O., Berger, J.-P., Bouzerand, E., Courtney-Barrer, B., Emsenhuber, A., Ertel, S., Gagne, J., Glauser, A., Gross, S., Ireland, M. J., Kenchington, H.-D., Kluska, J., Kraus, S., Labadie, L., Laborde, V., Léger, A., Leisenring, J., Loicq, J., Martin, G., Morren, J., Matter, A., Mazzoli, A., Missiaen, K., Muhammad, S., Ollivier, M., Raskin, G., Rousseau, H., Sanny, A., Verlinden, S., Vandenbussche, B., and Woillez, J., “L-band nulling interferometry at the VLTI with Asgard/Hi-5: Status and plans,” in [Optical and Infrared Interferometry and Imaging VIII], 12183, 184-199, SPIE (Aug. 2022).
Martinod, M.-A., Defrère, D., Ireland, M., Kraus, S., Martinache, F., Tuthill, P., Bigioli, A., Bouzerand, E., Bryant, J., Chhabra, S., Courtney-Barrer, B., Crous, F., Cvetojevic, N., Dandumont, C., Ertel, S., Gardner, T., Garreau, G., Glauser, A. M., Labadie, L., Lagadec, T., Laugier, R., Mazzoli, A., Mortimer, D., Norris, B., Raskin, G., Robertson, G., Sanny, A., and Taras, A., “High-angular resolution and high contrast observations from Y to L band at the Very Large Telescope Interferometer with the Asgard Instrumental suite,” Journal of Astronomical Telescopes, Instruments, and Systems 9, 025007 (Apr. 2023).
Garreau, G., Bigioli, A., Raskin, G., Berger, J.-P., Dandumont, C., Goldsmith, H.-D. K., Gross, S., Ireland, M., Labadie, L., Laugier, R., Loicq, J., Madden, S., Martin, G., Mazzoli, A., Morren, J., Shao, H., Yan, K., and Defrère, D., “Design of the VLTI/Hi-5 light injection system,” in [Optical and Infrared Interferometry and Imaging VIII], 12183, 719-734, SPIE (Aug. 2022).
Sanny, A., Gross, S., Labadie, L., Defrère, D., Bigioli, A., Laugier, R., Dandumont, C., and Withford, M. J., “Development of the four-telescope photonic nuller of Hi-5 for the characterization of exoplanets in the mid-IR,” in [Optical and Infrared Interferometry and Imaging VIII], Mérand, A., Sallum, S., and Sanchez-Bermudez, J., eds., 43, SPIE, Montréal, Canada (Aug. 2022).
Garreau, G., Bigioli, A., Laugier, R., Raskin, G., Morren, J., Berger, J.-P., Dandumont, C., Goldsmith, H.-D. K., Gross, S., Ireland, M., Labadie, L., Loicq, J., Madden, S., Martin, G., Martinod, M.-A., Mazzoli, A., Sanny, A., Shao, H., Yan, K., and Defrère, D., “Asgard/NOTT: L-band nulling interferometry at the VLTI. II. Warm optical design and injection system,” Journal of Astronomical Telescopes, Instruments, and Systems 10, 015002 (Jan. 2024).
Mathar, R. J., “Refractive index of humid air in the infrared: Model fits,” Journal of Optics A: Pure and Applied Optics 9, 470-476 (May 2007).
Tango, W. J., “Dispersion in stellar interferometry,” Applied Optics 29, 516 (Feb. 1990).
Laugier, R., Defrère, D., Woillez, J., Courtney-Barrer, B., Dannert, F. A., Matter, A., Dandumont, C., Gross, S., Absil, O., Bigioli, A., Garreau, G., Labadie, L., Loicq, J., Martinod, M.-A., Mazzoli, A., Raskin, G., and Sanny, A., “Asgard/NOTT: L -band nulling interferometry at the VLTI: I. Simulating the expected high-contrast performance,” Astronomy & Astrophysics 671, A110 (Mar. 2023).
Taras, A. K., Robertson, J. G., Allouche, F., Courtney-Barrer, B., Carter, J., Crous, F., Cvetojevic, N., Ireland, M., Lagarde, S., Martinache, F., McGinness, G., N'Diaye, M., Robbe-Dubois, S., and Tuthill, P., “Heimdallr, Baldr, and Solarstein: Designing the next generation of VLTI instruments in the Asgard suite,” Applied Optics 63, D41 (May 2024).
Lay, O., Jeganathan, M., and Peters, R., “ADAPTIVE NULLING: A NEW TOOL FOR INTERFEROMETRIC EXO-PLANET DETECTION,” ESA Special Publication (2003).
Peters, R. D., Lay, O. P., and Lawson, P. R., “Mid-Infrared Adaptive Nulling for the Detection of Earth-like Exoplanets,” Publications of the Astronomical Society of the Pacific, Volume 122, Issue 887, pp. 85 (2010). 122, 85 (Jan. 2010).
Angel, J. R. P. and Woolf, N. J., “An Imaging Nulling Interferometer to Study Extrasolar Planets,” The Astrophysical Journal 475(1), 373-379 (1997).
