Tag Archive for Redfield

Study by Redfield, Johnson ’11 Published in Astrophysical Journal, New Scientist

Seth Redfield, associate professor of astronomy, and Marshall Johnson ’11 are the co-authors of an article titled “The Interstellar Medium in the Kepler Search Volume,” published in The Astrophysical Journal, Vol. 802, No. 2, July 2015. The article highlights ways scientists are studying the gas and dust in the galaxy near where the Kepler Space Telescope is discovering exoplanets.

“Stars, with planets, can interact with the gas surrounding them in interesting ways, like bubbles in a drink, where each of the bubbles is an individual star (perhaps with planets) and the drink is the ‘interstellar medium’, the gas in between the stars,” Redfield explained.

In addition, The New Scientist published an article on Aug. 6 titled, “Distant worlds could be sheltering in a bubble around their star,” which focuses on the authors’ Astrophysical Journal study. It reads:

Distant planets may be swaddled in a protective bubble of magnetism and charged particles, courtesy of their parent star. The first study to scrutinize these so-called astrospheres shows that some exoplanets are more well shielded than Earth, others not so lucky – and that their protection can be fickle.

Within our solar system, the sun’s wind of charged particles and radiation forms a bubble called the heliosphere, which repels cosmic rays that can affect Earth’s weather, eat away at the ozone layer and damage DNA. Likewise, astrospheres guard faraway worlds from the ravages of the cosmos, says Marshall C. Johnson, an astronomer at the University of Texas in Austin.

An astrosphere’s size is determined partly by the strength of the star’s winds, and partly by the surrounding interstellar medium of gas and dust. The star’s velocity through the galaxy also has an effect.

“It’s just like if you are driving and you stick your hand out the window. You will experience higher pressure on your hand when you are driving fast than when you are driving slowly,” Johnson says. “If there is a greater relative velocity between the star and the interstellar medium, there will be a greater pressure exerted on the astrosphere.”

Johnson is working on his PhD in astronomy at the University of Texas in Austin. Marshall and Redfield had gone together in 2010-11 to observe at the McDonald Observatory in west Texas, and this project grew out of this work.

Another co-author on the paper, Adam Jensen, was a postdoctoral researcher at Wesleyan between 2010-2013 and was funded by the National Science Foundation.

Bow Shock Study by Redfield, Cauley Published in Astrophysical Journal

Seth Redfield, associate professor of astronomy, and Wilson Cauley, postdoctoral researcher in astronomy, led the effort on a paper titled “Optical hydrogen absorption consistent with a thin bow shock leading the hot Jupiter HD 189733b” accepted for publication in The Astrophysical Journal.

Wilson Cauley, postdoctoral researcher in astronomy, created a animation that shows the transit of bow shock material as it crosses a stellar disk, and the absorption values the model predicts. Cauley's study demonstrates an exciting path forward in attempting to measure exoplanet magnetic fields. 

Wilson Cauley, postdoctoral researcher in astronomy, created a animation that shows the transit of bow shock material as it crosses a stellar disk, and the absorption values the model predicts. Cauley’s study demonstrates an exciting path forward in attempting to measure exoplanet magnetic fields.

Bow shocks are ubiquitous astrophysical phenomena resulting from the supersonic passage of an object through a gas. In this paper, the authors present a robust detection of a time-resolved pre-transit, as well as in-transit, absorption signature around the hot Jupiter exoplanet HD 189733b using high spectral resolution observations of several hydrogen lines.

Better knowledge of exoplanet magnetic field strengths is crucial to understanding the role these fields play in planetary evolution and the potential development of life on planets in the habitable zone.

Cauley’s research is funded at Wesleyan through the National Science Foundation to study the extended atmospheres of exoplanets. For more information and to view a animation that summarizes the paper’s results, visit Cauley’s website.

In addition, Redfield and Cauley will present results from an observation made at the largest telescopes in the world, the Keck Telescope in Hawaii, during the International Astronomical Union General Assembly in August.


7 Faculty Promoted, Awarded Tenure

In its most recent meeting, the Board of Trustees promoted seven faculty members.

The BOT conferred tenure on Lauren Caldwell, associate professor of classical studies; Stephen Collins, associate professor of film studies; Paul Erickson, associate professor of history; Matthew Garrett, associate professor of English; Brian Northrop, associate professor of chemistry; Julia Randall, associate professor of art; and Seth Redfield, associate professor of astronomy.

The promotions are effective July 1, 2015.

Brief descriptions of their areas of research and teaching appear below.

Lauren Caldwell
Caldwell’s research focuses on Roman social history, Roman law, and Greco-Roman medicine. Her recent book, Roman Girlhood and the Fashioning of Femininity (Cambridge University Press, 2014) investigates the social pressures

Redfield Speaks about Magnetic Polarity Flipping on WNPR

Seth Redfield

Seth Redfield

Seth Redfield, assistant professor of astronomy, spoke with Patrick Skahill and WNPR News on Nov. 15 about the sun flipping its magnetic polarity, which only happens every 11 years. While the change in polarity is not fully understood by scientists, the event is exciting “because this is kind of a probe into the internal workings of the sun, which is actually really hard for us to get a handle on,” according to Redfield.

This solar cycle, Cycle 24, has not been disruptive to satellites or the electric grid, which can react negatively to solar radiation. The sun’s northern hemisphere flipped earlier this summer and the southern hemisphere is poised to flip very soon.

Read the article online here.

NASA’s Astronomy Picture of the Day Features Redfield’s Interstellar Medium

"The Local Fluff" by Seth Redfield, assistant professor of astronomy.

“The Local Fluff” by Seth Redfield, assistant professor of astronomy.

On Sept. 24, NASA’s Astronomy Picture of the Day featured a figure that Assistant Professor of Astronomy Seth Redfield generated as part of his research on the interstellar medium, the gas and dust surrounding the Sun and other nearby stars. Each day, NASA features a different image or photograph of the universe, along with a brief explanation written by a professional astronomer.

The explanation of the figure states: “The stars are not alone. In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM). The ISM is not uniform, and shows patchiness even near our Sun. It can be quite difficult to detect the local ISM because it is so tenuous and emits so little light. This mostly hydrogen gas, however, absorbs some very specific colors that can be detected in the light of the nearest stars.

A working map of the local ISM within 20 light-years, based on ongoing observations and recent particle detections from the Earth-orbiting Interstellar Boundary Explorer satellite (IBEX), is shown above. These observations indicate that our Sun is moving through a Local Interstellar Cloud as this cloud flows outwards from the Scorpius-Centaurus Association star forming region.

Our Sun may exit the Local Cloud, also called the Local Fluff, during the next 10,000 years. Much remains unknown about the local ISM, including details of its distribution, its origin, and how it affects the Sun and the Earth. Unexpectedly, recent IBEX spacecraft measurements indicate that the direction from which neutral interstellar particles flow through our Solar System is changing.”

Redfield Receives NSF Grant for Exoplanet Atmosphere Research

Seth Redfield, assistant professor of astronomy, won a three-year grant for $341,039 from the National Science Foundation Astronomy and Astrophysics Research Grants program to fund his research on “Accessing Atmospheric Properties of Terrestrial Exoplanets: Ground-Based Observations of Rayleigh Scattering and Extended Atmospheres.” The grant was awarded in August 2013.

Study by Redfield, Wyman MA ’11 Published in Astrophysical Journal, Forbes

Seth Redfield

Seth Redfield

Seth Redfield, assistant professor of astronomy, and Katy Wyman MA ’11, recently co-authored a paper that will appear in the Aug. 10 Astrophysical Journal, detailing several hundred spectral line measurements out to bright stars within 326 light years of our sun. Wyman is now employed at the Harvard-Smithsonian Center for Astrophysics.

The study also appeared in the July 28 edition of Forbes in an article titled “Looking In The Sun’s Rear-View Mirror: A New Map Of The Local Interstellar Medium.”

The first comprehensive map of the local interstellar medium — the gas drifting between the nearest stars — “will not only help theorists better understand the dynamics of our tiny swath of the galaxy, but represents the first crucial step in paving the way for interstellar travel,” the article reports.

Redfield, Wyman and their colleagues made their primary observations through the Hubble Space Telescope, the McDonald Observatory in Texas and the Australian Astronomical Observatory in New South Wales. Redfield says the plan is to publish a revised morphological model in the next six months.

Read the Forbes article online here.

Redfield Invited Speaker at Extrasolar Planets Conference in Germany

Seth Redfield

Seth Redfield, assistant professor of astronomy, spoke on “Properties of the Interstellar Medium Surrounding the Sun and Nearby Stars” during a conference held March 11-15 in the Physikzentrum in Bad Honnef, Germany.

The conference, which was 527th in a series, was sponsored by the Wilhelm und Else Heraeus Stiftung, a German foundation that supports scientific research and education. The topic of the conference was “Plasma and Radiation Environment in Astrospheres and Implications for the Habitability of Extrasolar Planets.”

Redfield’s Article Published by the Royal Astronomical Society

Seth Redfield, assistant professor of astronomy, is the co-author of “Probing potassium in the atmosphere of HD 80606b with tunable filter transit spectrophotometry from the Gran Telescopio Canarias,” published in the Monthly Notices of the Royal Astronomical Society, Volume 419, pages 2233-50, 2012.


Redfield, Herbst Discuss Transit of Venus on Fox 61

Bill Herbst discusses the Venus transit on Fox 61 news.

On a feature for Fox 61, Seth Redfield, assistant professor of astronomy, and Bill Herbst, chair and the John Monroe Van Vleck Professor of Astronomy, discussed the transit of Venus across the Sun, and showed viewers how Wesleyan would be marking the event with public viewings from Van Vleck Observatory.

“So here we have a case, where we can see the affect of a planet on a star, close up,” Herbst said in the feature, which aired on June 5.

The next transit won’t happen intil 2017.

“It’s a very wonderful opportunity to learn something new about planets and their atmospheres and solar systems in general,” Redfield said.