Planetary Science Directorate


Upcoming SwRI Boulder Colloquia

Colloquia are normally on Tuesdays at 11:00 am in the 4th-floor conference room, except as indicated below in bold text.
Show previous colloquia

For questions or suggestions for speakers, please contact the SwRI colloquium organizers:
Raluca Rufu, 303-226-0879 or raluca(at)
Julien Salmon, 720-208-7203 or julien(at)
Kelsi Singer, 303-226-5910 or ksinger(at)
Sierra Ferguson, sierra.ferguson(at)
Rogerio Deienno, rogerio.deienno(at)
Lena Heffern, lena.heffern(at)
Sam Van Kooten, 303-226-5909 or svankooten(at)

To be added to the SwRI Boulder Colloquia email list, please contact Kelsi Singer, ksinger(at)

Tue Mar 28, 2023
In CR4+ webex
11:00 am Daniel Carrera Iowa State University Challenges of planetesimal formation in dust rings
Abstract: The outer disk is a challenging region for planetesimal formation theory. Small particle sizes and fast radial drift make it difficult to collect enough solids to trigger planetesimal formation. The Streaming Instability (SI) is a promising mechanism that has drawn a lot of attention in recent years. I will present evidence that the small grain sizes and large pressure gradient of the outer disk might not allow the SI to form planetesimals in the dust rings observed by ALMA. We conducted the largest simulation of the SI so far, consisting of a large slice of the disk with mm grains, a solar-like dust-to-gas ratio (Z = 0.01), and the largest pressure bump that does not cause gravitational instability (GI) in the particle layer. We used a high resolution to resolve as many SI unstable modes as possible. The simulation produced a large and long-lived particle over-density, but no planetesimals, or even dust filaments normally associated with the SI. We argue that the limiting factor might be that the time it takes for particles to cross the dust ring is shorter than the growth timescale of the SI. This result restricts the pathways for planet formation and requires a re-thinking of our planetesimal formation model.
Tue Apr 4, 202311:00 am Ekaterina Landgren CU CIRES TBD
Tue Apr 11, 2023
In CR4+ webex
11:00 am Perianne Johnson CU Boulder Modeling Pluto's Atmosphere and Volatile Inventory Throughout Time
Thu Apr 13, 2023
In CR4 + virtual
11:00 am Robert Jarolim Solarnet TBD
Tue Apr 18, 2023
In CR4+ webex
11:00 am Christopher Glein SwRI San Antonio Is there P in Enceladus’s ocean? – A chronicle of habitability
Tue May 16, 2023
In CR4+ webex
11:00 am Sam Birch MIT TBD
Tue Sep 12, 202311:00 am Michael S. P. Kelley University of Maryland TBD