1. The Universal Presence of Nightside Clouds
on Hot Jupiters
Assistant Astronomer
Steward Observatory – University of Arizona
Thomas G. Beatty

2. From optical Hubble observations, we know that clouds exist at planetary dusk and dawn
Sing et al.
(2015)

3. ? ? But we did not know: How common are clouds on hot Jupiters?
What are the cloud properties of the daysides and nightsides?
Where does cloud formation occur? ? ?

4. Phase curves watch an exoplanet for an entire orbit, and show day-to-night atmospheric changes

5. Phase curves are the main way we study the global climates of hot Jupiters

6. A main result from the last few years of study has been that hotter planets show larger day-night temperature contrasts
Beatty et al. (2018)

7. faster heat
re-radiation
transport
This has been thought to occur because of the changing balance between heat transport and re-radiation in planetary atmospheres
Beatty et al. (2018)

8. But it also requires fine tuning to work for all hot Jupiters…
faster heat
re-radiation
transport
This balancing act should to tell us something about the atmospheric dynamics.
But it also requires fine tuning to work for all hot Jupiters…
Beatty et al. (2018)

9. Spitzer phase curves of the hot brown dwarf KELT-1b
Beatty et al. (2018)

10. Because KELT-1b is 28 MJ, the IR photosphere is at much higher pressure than for a typical hot Jupiter
We expected to see a much smaller day-to-night
temperature contrast than for a typical hot Jupiter.

11. But KELT-1b matches the hot Jupiter trend
Beatty et al. (2018)

12. The temperatures shows that all the nightsides are roughly the same at 1000K!
clear
daysides
cloudy
nightsides
Nightside clouds are clamping
the nightside emission to 1000K
Beatty et al. (2018)

13. So instead of a delicate thermal balancing act…
faster
transport
faster
re-radiation
Beatty et al. (2018)

14. nightside
clouds
The universal presence of nightside clouds naturally explains this trend, by forcing us to see all the nightsides at 1000K
Beatty et al. (2018)

15. ? ? How common are clouds on hot Jupiters?
What are the cloud properties of the daysides and nightsides?
Where does cloud formation occur? ? ?

16. How common are clouds on hot Jupiters?
What are the cloud properties of the daysides and nightsides?
Where does cloud formation occur?
Clouds appear to be present on the nightsides of all hot Jupiters.
Based on the 1000K temperature,
probably silicate or manganese clouds
Clouds most likely form near planetary dusk, and burn-off near dawn.

17. And stay tuned for Hubble
observations where we
try to measure the cloud
properties directly!