Proxima Centauri

Behind The Mask: Can HARMONI@ELT Detect Biosignatures In The Reflected Light Of Proxima b?

By Keith Cowing
Status Report
January 19, 2024
Filed under , , , , , , , ,
Behind The Mask: Can HARMONI@ELT Detect Biosignatures In The Reflected Light Of Proxima b?
Signal-to-noise of the fiducial planet simulation. The top panel shows two slices of the CCF cube, one in the plane on the sky and one along the velocity axis. The bottom panels show the same two slices separated for clarity with pink dashed lines indicating the expected position of the signal. The region covered by the FPM is greyed-out. The bottom left panel shows the signal-to-noise for the spaxels along spaxel 푥 = 0 for different velocities relative to the exoplanet’s velocity. The bottom right panel shows the signalto-noise of all the spaxels at a Doppler shift equal to the exoplanet’s velocity. The yellow star in the bottom right panel indicates the location of the star. Note that this injected fiducial exoplanet does not represent Proximab. — astro-ph.EP

Proxima b is a rocky exoplanet in the habitable zone of the nearest star system and a key test case in the search for extraterrestrial life.

Here, we investigate the characterization of a potential Earth-like atmosphere around Proxima b in reflected light via molecule mapping, combining high resolution spectroscopy (HRS) and high contrast imaging, using the first-generation integral field spectrograph HARMONI on the 39-m Extremely Large Telescope.

We simulate comprehensive observations of Proxima b at an assumed 45∘ inclination using HARMONI’s High Contrast Adaptive Optics mode, with spatial resolution ∼8mas (3.88mas/spaxel) and spectral resolving power R≃17,000 between 1.538–1.678μm, containing the spectral features of water, carbon dioxide and methane. Tellurics, stellar features, and additional noise sources are included, and removed using established molecule mapping techniques.

We find that HARMONI’s current focal plane mask (FPM) is too large and obscures the orbit of Proxima b and thus explore smaller and offset FPMs to yield a detection. A S/N=5 detection of Proxima b’s reflected light, suitable for atmospheric characterisation, is possible with such modifications, requiring a minimum of 20 hours, but ideally at least 30 hours of integration time.

We highlight that such detections do not scale with the photon noise, hence suitably detailed simulations of future instruments for the ELTs are needed to fully understand their ability to perform HRS observations of exoplanet atmospheres. Alterations to the HARMONI FPM design are feasible at this stage, but must be considered in context of other science cases.

Sophia R. Vaughan (1), Jayne L. Birkby (1), Niranjan Thatte (1), Alexis Carlotti (2), Mathis Houllé (3), Miguel Pereira-Santaella (4), Fraser Clarke (1), Arthur Vigan (5), Zifan Lin (6), Lisa Kaltenegger (7,8) ((1) Department of Physics, University of Oxford, Oxford, OX1 3RH, UK, (2) Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France, (3) Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, 06304 Nice, France, (4) Instituto de Física Fundamental, CSIC, Serrano 123, 28006 Madrid, Spain, (5) Aix Marseille Univ., CNRS, CNES, LAM, 13388 Marseille, France, (6) Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA, (7) Carl Sagan Institute, Cornell University, 302 Space Sciences Building, Ithaca, NY 14853, USA, (8) Astronomy Department, Cornell University, 302 Space Sciences Building, Ithaca, NY 14853, USA)

Comments: 14 pages, 9 figures, accepted to MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2401.09589 [astro-ph.EP] (or arXiv:2401.09589v1 [astro-ph.EP] for this version)
Submission history
From: Sophia Vaughan
[v1] Wed, 17 Jan 2024 20:35:15 UTC (2,176 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻