WEATHER ON OTHER WORLDS. II. SURVEY RESULTS: SPOTS ARE UBIQUITOUS ON L AND T DWARFS

By S. Metchev, A. Heinze, D. Apai, Davin Flateau, Jacqueline Radigan, A. Burgasser, M. Marley, É. Artigau, P. Plavchan, B. Goldman. 2014

141 citations recorded by the source corpus.

We present results from the Weather on Other Worlds Spitzer Exploration Science program to investigate photometric variability in L and T dwarfs, usually attributed to patchy clouds. We surveyed 44 L3–T8 dwarfs, spanning a range of J − Ks colors and surface gravities. We find that 14/23 (, 95% confidence) of our single L3–L9.5 dwarfs are variable with peak-to-peak amplitudes between 0.2% and 1.5%, and 5/16 () of our single T0–T8 dwarfs are variable with amplitudes between 0.8% and 4.6%. After correcting for sensitivity, we find that of L dwarfs vary by ⩾0.2%, and of T dwarfs vary by ⩾0.4%. Given viewing geometry considerations, we conclude that photospheric heterogeneities causing >0.2% 3–5 μm flux variations are present on virtually all L dwarfs, and probably on most T dwarfs. A third of L dwarf variables show irregular light curves, indicating that L dwarfs may have multiple spots that evolve over a single rotation. Also, approximately a third of the periodicities are on timescales >10 hr, suggesting that slowly rotating brown dwarfs may be common. We observe an increase in the maximum amplitudes over the entire spectral type range, revealing a potential for greater temperature contrasts in T dwarfs than in L dwarfs. We find a tentative association (92% confidence) between low surface gravity and high-amplitude variability among L3–L5.5 dwarfs. Although we can not confirm whether lower gravity is also correlated with a higher incidence of variables, the result is promising for the characterization of directly imaged young extrasolar planets through variability.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/8208a7277e16bd346f94597ab1f865a4c1843785

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In Astronomy and Astrophysics

1. B. Bowler
2. N. Madhusudhan
3. Q. Konopacky
4. B. Macintosh
5. Travis S. Barman
6. C. Marois
7. M. Line
8. V. Parmentier

In Instrumentation

1. B. Bowler
2. B. Macintosh
3. C. Marois
4. V. Parmentier
5. Q. Konopacky
6. Travis S. Barman
7. M. Line
8. N. Madhusudhan

In Statistical and Nonlinear Physics

1. B. Macintosh
2. C. Marois
3. B. Bowler
4. M. Line
5. Travis S. Barman
6. V. Parmentier
7. Jon Fortney

Citations in the corpus

• SIMULTANEOUS DETECTION OF WATER, METHANE, AND CARBON MONOXIDE IN THE ATMOSPHERE OF EXOPLANET HR 8799 b (2015, background): “It is also possible that HR8799 b is variable as indicated by studies of brown dwarfs (Metchev et al. 2015).”
• THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA (2015, background): “…are presumed to happen in Brown dwarf atmospheres (Burgasser et al. 2002; Marley et al. 2010; Zhang & Showman 2014), where observations are strongly suggestive of non-uniform cloud cover (Buenzli et al. 2012;14; Radigan et al. 2012;14; Crossfield et al. 2014; Apai et al. 2013; Metchev et al. 2015).”
• Imaging Extrasolar Giant Planets (2016, background): “Photometric variability from rapidly changing or rotationally-modulated surface features can introduce uncertainties in relative photometry (e.g., Radigan et al. 2014; Metchev et al. 2015; Zhou et al. 2016; Biller et al. 2015a).”