Astronomy & Telescopes

Characterizing Earth-like Planets Using Spectroscopy and High-Contrast Instruments

By Keith Cowing
September 21, 2014
Filed under
Characterizing Earth-like Planets Using Spectroscopy and High-Contrast Instruments

Future radial velocity, astrometric and direct imaging surveys will find nearby Earth-sized planets within the habitable zone (HZ) in the near future. How can we search for water and oxygen in those non-transiting planets?

We propose a combination of high-dispersion spectroscopy and coronagraphic techniques as a method to detect molecular lines in Earth-like planets (ELPs). In this method, the planetary signals are spectroscopically separated from the telluric absorption due to the Doppler shift. Assuming a long observing campaign ( T exp = 20 days) using the high-dispersion spectrometer ( R=50,000 ) with the speckle suppression on a 30 m telescope, we simulate the spectra from the ELPs around M dwarfs at 5 pc.

Performing the cross-correlation analysis with the binary template of the molecular lines, we find that the raw contrasts of 10 −4 (0.8-1.8 μ m) and 10 −4.5 (use of J-band only) at 30 mas are required to detect the water vapor for a ∼4−5σ detection. The raw contrast of 10 −5 is required for a 4 σ detection of the oxygen 1.27 μ m band. For the ELPs around solar-type stars, it is necessary to assume a several hundred times better contrast than that for M dwarfs in order to detect water vapor. This method does not require any additional post-processings and is less sensitive to the terrestrial noise than the low resolution spectroscopy. We conclude that a combination of high-dispersion spectroscopy and high-contrast instruments can be a powerful means to characterize the ELPs in the extremely large telescope era.

Characterizing Earth-like Planets Using a Combination of High-Dispersion Spectroscopy and High-Contrast Instruments: Doppler-shifted Water and Oxygen Lines Hajime Kawahara

(Submitted on 19 Sep 2014)

Comments: 11 pages, 9 figures, submitted to ApJ. High resolution version may be found at this http URL Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1409.5740 [astro-ph.EP] (or arXiv:1409.5740v1 [astro-ph.EP] for this version)

Submission history From: Hajime Kawahara [v1] Fri, 19 Sep 2014 17:45:09 GMT (1275kb)

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) 🖖🏻