Feature-rich transmission spectrum for WASP-127b. Cloud-free skies for the puffiest known super-Neptune?
Abstract
Context. WASP-127b is a planet with one of the lowest densities discovered to date. With a sub-Saturn mass (Mp = 0.18 ± 0.02 MJ) and super-Jupiter radius (Rp = 1.37 ± 0.04 RJ), it orbits a bright G5 star that is about to leave the main-sequence.
Aims: We aim to explore the atmosphere of WASP-127b in order to retrieve its main atmospheric components, and to find hints for its intriguing inflation and evolutionary history.
Methods: We used the ALFOSC spectrograph at the NOT telescope to observe a low-resolution (R 330, seeing limited) long-slit spectroscopic time series during a planetary transit, and present here the first transmission spectrum for WASP-127b.
Results: We find a strong Rayleigh slope at blue wavelengths and a hint of Na absorption, although the quality of the data does not allow us to claim a detection. At redder wavelengths the absorption features of TiO and VO are the best explanation to fit the data.
Conclusions: Although observations with a higher signal-to-noise ratio are needed to conclusively confirm the absorption features, WASP-127b seems to posses a cloud-free atmosphere and is one of the best targets on which to perform further characterization studies in the near future.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2017
- DOI:
- 10.1051/0004-6361/201731018
- arXiv:
- arXiv:1705.09230
- Bibcode:
- 2017A&A...602L..15P
- Keywords:
-
- planetary systems;
- planets and satellites: individual: WASP-127b;
- planets and satellites: atmospheres;
- techniques: spectroscopic;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted for Publication A&