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Scialog 2015: Time Domain Astrophysics Produces a Record Number of Proposals

The 49 Scialog Fellows who attended the first of two Scialog conferences on Time Domain Astrophysics (TDA), Oct. 22-25, produced 30 team proposals for potential funding – more than any other Scialog event, according to Richard Wiener, Scialog program director. The Fellows were joined by 10 world- leading researchers as facilitators.

The proposals centered largely on the pursuit of fundamental research into astrophysical dynamics – the myriad ways in which the many varieties of stars, black holes and galaxies function, evolve over eons and eventually die, sometimes in spectacular explosions.

Scialog conferences are unique in that the only formal presentations are a couple keynote presentations to set the stage for breakout discussions, which lead to team formation and the writing of proposals at the conference for seed funding of blue-sky ideas that emerge from the dialog. Members of 2-3 person teams consist of Scialog Fellows who have not previously collaborated and typically include theorists and observers.

In his keynote address, theoretical astrophysicist Lars Bildsten, KITP, University of California, Santa Barbara, informally set the parameters of subsequent Scialog small-group discussions by reporting on the latest understanding of data from the Kepler Space Telescope, launched in early 2009 with the primary mission to discover Earth-like planets orbiting other stars.

Bildsten noted Kepler has also triggered a revolution in stellar-oriented TDA. “The revolution has been motivated by Kepler data that, for those of us who care about stars, has enabled us to ask and answer questions that were previously out of reach.”

For example, he said Kepler data opens possible avenues to measure core rotation rates of red giant stars; core rotation can impact the later evolution of a star, particularly massive stars many times larger than the sun.

The data will also help answer questions about many other forces within stars, including the behavior of acoustic waves as well as convection processes, and how they contribute to additional stellar phenomena.

Bildsten praised NASA for doing “innovative things” with Kepler, including pointing the telescope at a new patch of space every few months. He predicted the changing fields of view will give astronomers opportunities to study many different types of massive stars, not only in the galactic plane, where most stars reside, but also above and below the plane in open clusters, where stars are loosely bound by gravity (as opposed to tightly bound stars in globular clusters).

Bildsten said additional space-based telescopes to be launched in the coming years (e.g., PLATO and TESS), although primarily designed to detect planets transiting stars, likely will provide ample material for stellar theorists for years to come.

Shrinivas Kulkarni, FRS, professor of astrophysics and planetary science at Caltech, pointed out in his keynote address that the field of Time Domain Astrophysics seems to be growing exponentially these days. He broadly divided “explosive TDA” into two fields – “recurrent,” in which novae events, for example, occur repeatedly over time, and “catastrophic,” which include events that essentially end the lives of stars.

Kulkarni noted that the observational principle of “cadence and control” – generally relating to periodicity and the precision of measurement -- is important to both recurrent and catastrophic TDA, but more so in observing catastrophic stellar events such as supernovae and tidal disruptions (when a star is pulled apart by a supermassive black hole). 

“Most astronomers don’t really ‘get’ cadence and control,” he said, noting the concept goes back to Caltech-based astronomer Fritz Zwicky in the mid-20th century. Zwicky coined the term “supernova” and theorized the process led to the formation of neutron stars.

“The idea of visualizing the star rates [of change] actually goes to Zwicky,” Kulkarni said. “He envisioned a phase space with peak brightness on one access and duration on the other access. In this way he was able to make the distinction between novae and supernovae.”

Using this fundamental tool and others, astronomers have since come up with many different classes of exploding stars; and the discoveries continue, so much so, Kulkarni said, that the study of supernovae now constitute one of the major frontiers in astronomical research.

He also expressed excitement for upcoming instrument projects in transient object astronomy, including the Large Synoptic Survey Telescope (LSST), “the greatest contribution to this branch of astronomy.” The LSST, like other transient object instruments, makes a broad survey of the night sky at successive intervals, allowing scientists to notice movement and change.

The LSST is now under construction on the Cerro Pachón ridge in north-central Chilé.  According to the LSST website, it is designed to conduct a deep survey over an enormous area of sky; do it with a frequency that enables images of every part of the visible sky to be obtained every few nights; and continue in this mode for 10 years to achieve astronomical catalogs thousands of times larger than previous compilations.

In remarks opening the Scialog conference, RCSA Board Member Elizabeth McCormack, associate provost and professor of physics at Bryn Mawr College, said the LSST is merely the latest example of RCSA’s “special kinship” with the fields of astronomy and astrophysics. She noted that former Research Corporation President John Schaefer was a key founding member in the collaboration that created the LSST.

McCormack also pointed out that Research Corporation was a very early supporter of radio astronomy through the pioneering work of Grote Reber.  And “Research Corporation has also been a key player in the development and support of the innovative Large Binocular Telescope atop Mt. Graham in Southeastern Arizona,” McCormack added. “These exceptional instruments promote collaboration and cross-disciplinary interactions, two factors Research Corporation tirelessly encourages across all of the physical sciences.”

Scialog Program Director Richard Wiener explained to conference participants that the Scialog process focuses on team building with the goal of creating novel strategies and collaborative approaches.

“Judging by the terrific discussions, high number of proposals and tremendous enthusiasm of Scialog Fellows, this latest Scialog, the first on Time Domain Astrophysics, is a huge success,” Wiener said.  “Research Corporation could not be more pleased.”

He added the proposals are currently being evaluated with the expectation that at least five will be funded by the end of 2015. 

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