"News Vacuum" | Letter from the Director | November 2019

Newspapers float around in the vacuum of space.
News articles, floating around in the vacuum of space, wait to be collected by the new DTM communications coordinator.
Monday, November 25, 2019 

News Vacuum

Hopefully, you noticed and have been bemoaning the fact that the DTM newsletter went on an extended vacation this Summer and early Fall.  The gap in news reporting is not due to a lack of news, as you will see below, but a transition in our communications staff. Our former communications coordinator, Roberto Molar Candanosa moved on to become a Science Reporter for Northeastern University.  Our new communications coordinator, Katherine Cain, joined us from her previous job as Communications Manager for the Rock Creek Conservancy. The job of the communications coordinator involves an interesting mix of science and art, with each of our previous communications coordinators bringing their own style to the job.  We welcome Katherine (Katy) to the Carnegie family and look forward to the applications of her style to convey the excitement of the science we do on campus.

The Moon Contest

The three-month hiatus in our newsletter reveals the abundance of exciting discoveries being made on a routine basis by DTM scientists. In space science, Scott Sheppard continues his remarkable record of finding small objects in the outer reaches of our Solar System, this time reporting the discovery of 20 new moons orbiting Saturn.  Scott’s discoveries bring Saturn’s moon total to 82, taking it past the previous moon-king Jupiter that has ONLY 79 moons. As with his discovery of Jupiter moons, Scott initiated a social media contest to name the new Saturnian moons. Saturn's moons must be named after giants from Norse, Gallic, or Inuit mythology.

Students from Lanivet School in Cornwall England were among those who suggested Pandia, daughter of Zeus and Selene, for one of Jupiter's newly discovered moons. Credit: Lanivet Junior & Infants School

My favorite result from the Jupiter moon-naming contest is Pandia, named after the daughter of Zeus and the Moon goddess Selene. While meeting the requirement that Jupiter moons be named after descendants or consorts of Zeus or Jupiter, Pandia also reflects the Panda mascot of the astronomy club of the Lanivet School in Cornwall, England, who was one of the entries to suggest Pandia. The Saturn moon naming contest ends on December 6.

Planet Transits and Exoplanets

Mercury appears as a small dot against the background of the Sun. The next transit of Mercury that will be visible from the United States will not occur until May 7, 2049. Credit: Tri Astraatmaja

At the other end of our Solar System, DTM’s postdoctoral fellow Tri Astraatmadja set up the telescope willed to DTM by our former staff astronomer John Graham to observe the small spot as Mercury passed between Earth and the Sun. This planetary detection technique is the same used by the Kepler and TESS spacecraft to discover thousands of planets orbiting other stars in the Milky Way.

We were excited to see that the other prominent technique used to detect exoplanets, the radial velocity method, pioneered by our staff scientist Paul Butler, resulted in this year’s Nobel Prize in physics for the first detection in 1995 of a planet around a star similar to the Sun. We continue to be amazed by the diversity of planets observed around other stars. The architecture of our Solar System is so different from these other systems in its lack of gas giant planets (e.g., Jupiter) orbiting close to its star. In addition, the most abundant exoplanets are about 1.5 to 3 times the size of Earth, which is a planet-size that does not exist in our Solar System.

The diversity of exoplanetary system architectures is sending our models of planet formation back to the starting line, highlighting that there may be more than one way to form a planet.   A good example is the recent discovery of a gas giant planet orbiting a star that is a tenth the mass of the Sun.  This large ratio of planet to star size suggests a rapid planet formation mechanism that allows the planet to grow to sufficient mass quickly enough to retain nebular gas. The popularly accepted "core accretion" mechanism can't account for this rapid growth. Instead, these gas giants may be explained by the “disk instability” planet-growth mechanism, pursued by staff scientist Alan Boss. In this model, “clumpiness” within the disk of dust and gas orbiting a newly-formed star allows the assembly of enough material into a small enough space where its own gravity draws all the material into a single large planet. 

In a related effort, DTM’s Sagan Fellow Jaehan Bae has been exploring how the velocity of gas in the disk of material around stars in the process of forming planetary systems can be used to track the presence of planets, still too small to be observed, growing in the disk. The work combines theoretical considerations with the incredible images of circumstellar disks being produced by the Atacama Large Millimeter Array radiotelescope in Chile. 

Living on an Active Planet 

Image of Telica Volcano in Nicaragua, the subject of Diana Roman's decade-long study into persistently restless volcanoes. Credit:  Diana Roman | Carnegie Institution for Science

Closer to home, staff scientist Diana Roman reported the results of a decade-long study of the Telica volcano in Nicaragua that has been in a state of on-again-off-again eruption throughout the study. Diana’s work provides a number of insights into what aspects of the underground plumbing system is controlling both the timing and size of eruptions. The work is an important step to developing forecasting methods that can help minimize the hazards associated with volcanic eruptions at these persistently restless volcanoes. 
Understanding the structures and forces driving geologic phenomena from below also was the subject of a podcast produced by the American Geophysical Union about staff scientist Lara Wagner’s work. Lara uses seismic waves from distant earthquakes to look inside Earth to explore the dynamics of Earth’s interior.
The activity within our geophysics group was further enhanced by the presence of two Tuve Senior Fellows in October and November, seismologist Geoff Abers from Cornell University and geodesist Kurt Feigl from the University of Wisconsin.  The Tuve Senior Fellowship fund, named after former (1946-1966) DTM Director Merle Tuve, was started by donations from former DTM scientific staff Thomas Aldrich, Philip Abelson, Louis Brown, Kent Ford, Vera Rubin, and Selwyn Sacks, among others. The fund received a recent boost with contributions in memory of Erik Hauri and J.N. Nanda. The Tuve fund sponsors short-term visits from prominent senior scientists for collaborative work with DTM scientists.

Recognition of Carnegie Scientists

Speaking of AGU, we are proud to report that 8 current or former DTM or GL colleagues across the whole range of career stages will be presented with major awards from AGU at the upcoming annual AGU meeting in San Francisco.  The list includes Mike Walter, Bob Hazen, Graham Pearson and James Farquhar (AGU Fellows), Richard Walker (Hess Medal), Graham Pearson (Bowen Award), Marion Garçon (Kuno Award), Sergey Lobanov (Early Career Award), and Kathryn Kumamoto (Graduate Research Award).  We congratulate these colleagues in the well-deserved recognition of their important contributions and promise from the largest professional society in Earth science and take pride in the various roles the Carnegie Institution has played in helping them to excel.

Richard Carlson, Director, DTM
Carnegie Institution for Science