Cloud Atlas: Rotational Spectral Modulations and Potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C
Lew, Ben W. P.
Burgasser, Adam J.
Miles-Páez, Paulo A.
Lowrance, Patrick J.
Bedin, Luigi R.
Marley, Mark S.
AffiliationUniv Arizona, Steward Observ, Dept Astron
Univ Arizona, Lunar & Planetary Lab, Dept Planetary Sci
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationElena Manjavacas et al 2019 ApJL 875 L15
JournalASTROPHYSICAL JOURNAL LETTERS
Rights© 2019. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractMeasurements of photometric variability at different wavelengths provide insights into the vertical cloud structure of brown dwarfs and planetary-mass objects. In seven Hubble Space Telescope consecutive orbits, spanning similar to 10 hr of observing time, we obtained time-resolved spectroscopy of the planetary-mass T8 dwarf Ross. 458 C using the near-infrared Wide Field Camera 3. We found spectrophotometric variability with a peak-to-peak signal of 2.62 +/- 0.02% (in the 1.10-1.60 mu m white light curve). Using three different methods, we estimated a rotational period of 6.75 +/- 1.58 hr for the white light curve, and similar periods for narrow J- and H-band light curves. Sine wave fits to the narrow J- and H-band light curves suggest a tentative phase shift between the light curves with wavelength when we allow different periods between both light curves. If confirmed, this phase shift may be similar to the phase shift detected earlier for the T6.5 spectral type 2MASS J22282889-310262. We find that, in contrast with 2M2228, the variability of Ross. 458C shows evidence for a color trend within the narrow J-band, but gray variations in the narrow H-band. The spectral time-resolved variability of Ross. 458C might be potentially due to heterogeneous sulfide clouds in the atmosphere of the object. Our discovery extends the study of spectral modulations of condensate clouds to the coolest T-dwarf, planetary-mass companions.
VersionFinal published version
SponsorsNASA [NAS 5-26555, GO-14241]; National Aeronautics and Space Administration; National Science Foundation