From The Eberly College of Science at The Pennsylvania State University (US) : “Coronal rain on a cold star?”

From The Eberly College of Science (US)



Penn State Bloc

The Pennsylvania State University (US)

December 17, 2021

Suvrath Mahadevan
Work Phone: +1 814-865-0261

Sam Sholtis
Work Phone: 814-865-1390

Observations of a distant stellar flare could contain the first evidence of coronal rain on a cool, small M-dwarf star.

Coronal rain on the sun with Earth superimposed for scale. New high-resolution spectrographic observations of a flare on a faint distant star using the Penn State Habitable-zone Planet Finder could contain the first evidence of a similar phenomenon on an ultracool, small M-dwarf star. Credit: NASA/SDO. All Rights Reserved.

NASA Solar Dynamics Observatory

High-resolution spectroscopic observations of a stellar flare on a small, cool star indicate the possibility of coronal rain, a phenomenon that has been observed on our sun but not yet confirmed on a star of this size. This faint star, known as vB 10, which is about a tenth the size of the sun and produces less than 1% of the sun’s energy, was studied using the Penn State Habitable-zone Planet Finder (HPF) at the large Hobby Eberly Telescope (with its 10 m mirror).

U Texas McDonald Observatory Hobby-Eberly 9.1 meter Telescope, Altitude 2,070 m (6,790 ft)

These observations with the HPF spectrograph allowed researchers to measure a shift in the wavelength of certain atomic lines from the flare that are consistent with hot plasma raining back down on the star’s surface and are similar to observations of coronal rain from the sun.

A paper describing the observations, by a team led by Penn State scientists, includes a time-series analysis of the flare and could help astronomers put constraints on the energy and frequency of such events. The paper has been accepted for publication in The Astrophysical Journal.

“As the name suggests, the Habitable-zone Planet Finder was designed to detect planets by looking for shifts in the light spectra from M-dwarf stars that result from the star ‘wobbling’ under the gravitational pull of orbiting planets,” said Larry Ramsey, professor emeritus of astronomy and astrophysics at Penn State and an author of the paper. “But we knew from the start that we might learn more about stellar activity from these spectra than we do about planets.”

The star is classified as an “ultracool dwarf” — it is close in size to Jupiter — and is among the smallest stars that can still fuse hydrogen to helium. It was observed by HPF as part of its normal, planet-hunting operations but subsequent analysis revealed a huge spike in the star’s emissions consistent with a stellar flare.

Flares are short-lived, intense eruptions of energy on stellar surfaces. Astronomers don’t know exactly what causes them, but the current best hypothesis is that when magnetic field lines on stellar surfaces rupture and reconnect they release a lot of energy, some of which is converted to thermal energy which accelerates ions and electrons on the star to extreme speeds. Some of the gas near the event rushes back toward the star’s surface and some is shot out above the flare.

“Stellar flares are common on M-dwarf stars,” said Shubham Kanodia, a graduate student at Penn State and lead author of the paper. “But because of the high-resolution of the HPF spectrograph, we were able to detect some unusual characteristics in the spectra from this flare.”

HPF detected emission from several atoms that were excited to high energy states by the flare. In particular, emission lines from the atomic transitions of helium atoms showed a slight shift toward longer wavelengths, known as a “red shift.” This shift shows that the excited atoms that emitted this light, were falling towards the star with a velocity of about 70 kilometers per second.

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The Eberly College of Science is the science college of Penn State University, University Park, Pennsylvania. It was founded in 1859 by Jacob S. Whitman, professor of natural science. The College offers baccalaureate, master’s, and doctoral degree programs in the basic sciences. It was named after Robert E. Eberly.

Eberly College of Science offers sixteen majors in four disciplines: Life Sciences, Physical Sciences, Mathematical Sciences and Interdisciplinary Studies.[2]
• The Life Sciences: Biology, Biochemistry & Molecular Biology, Biotechnology, Microbiology
• The Physical Sciences: Astronomy & Astrophysics, Chemistry, Physics, Planetary Science and Astronomy
• The Mathematical Sciences: Mathematics, Statistics, Data Sciences
• Interdisciplinary Programs: General Science, Forensic Science, Premedicine, Integrated Premedical-Medical, Science BS/MBA

The Pennsylvania State University (US) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers’ High School of Pennsylvania, Penn State became the state’s only land-grant university in 1863. Today, Penn State is a major research university which conducts teaching, research, and public service. Its instructional mission includes undergraduate, graduate, professional and continuing education offered through resident instruction and online delivery. In addition to its land-grant designation, it also participates in the sea-grant, space-grant, and sun-grant research consortia; it is one of only four such universities (along with Cornell University(US), Oregon State University(US), and University of Hawaiʻi at Mānoa(US)). Its University Park campus, which is the largest and serves as the administrative hub, lies within the Borough of State College and College Township. It has two law schools: Penn State Law, on the school’s University Park campus, and Dickinson Law, in Carlisle. The College of Medicine is in Hershey. Penn State is one university that is geographically distributed throughout Pennsylvania. There are 19 commonwealth campuses and 5 special mission campuses located across the state. The University Park campus has been labeled one of the “Public Ivies,” a publicly funded university considered as providing a quality of education comparable to those of the Ivy League.

Annual enrollment at the University Park campus totals more than 46,800 graduate and undergraduate students, making it one of the largest universities in the United States. It has the world’s largest dues-paying alumni association. The university offers more than 160 majors among all its campuses.

Annually, the university hosts the Penn State IFC/Panhellenic Dance Marathon (THON), which is the world’s largest student-run philanthropy. This event is held at the Bryce Jordan Center on the University Park campus. The university’s athletics teams compete in Division I of the NCAA and are collectively known as the Penn State Nittany Lions, competing in the Big Ten Conference for most sports. Penn State students, alumni, faculty and coaches have received a total of 54 Olympic medals.

Early years

The school was sponsored by the Pennsylvania State Agricultural Society and founded as a degree-granting institution on February 22, 1855, by Pennsylvania’s state legislature as the Farmers’ High School of Pennsylvania. The use of “college” or “university” was avoided because of local prejudice against such institutions as being impractical in their courses of study. Centre County, Pennsylvania, became the home of the new school when James Irvin of Bellefonte, Pennsylvania, donated 200 acres (0.8 km2) of land – the first of 10,101 acres (41 km^2) the school would eventually acquire. In 1862, the school’s name was changed to the Agricultural College of Pennsylvania, and with the passage of the Morrill Land-Grant Acts, Pennsylvania selected the school in 1863 to be the state’s sole land-grant college. The school’s name changed to the Pennsylvania State College in 1874; enrollment fell to 64 undergraduates the following year as the school tried to balance purely agricultural studies with a more classic education.

George W. Atherton became president of the school in 1882, and broadened the curriculum. Shortly after he introduced engineering studies, Penn State became one of the ten largest engineering schools in the nation. Atherton also expanded the liberal arts and agriculture programs, for which the school began receiving regular appropriations from the state in 1887. A major road in State College has been named in Atherton’s honor. Additionally, Penn State’s Atherton Hall, a well-furnished and centrally located residence hall, is named not after George Atherton himself, but after his wife, Frances Washburn Atherton. His grave is in front of Schwab Auditorium near Old Main, marked by an engraved marble block in front of his statue.

Early 20th century

In the years that followed, Penn State grew significantly, becoming the state’s largest grantor of baccalaureate degrees and reaching an enrollment of 5,000 in 1936. Around that time, a system of commonwealth campuses was started by President Ralph Dorn Hetzel to provide an alternative for Depression-era students who were economically unable to leave home to attend college.

In 1953, President Milton S. Eisenhower, brother of then-U.S. President Dwight D. Eisenhower, sought and won permission to elevate the school to university status as The Pennsylvania State University. Under his successor Eric A. Walker (1956–1970), the university acquired hundreds of acres of surrounding land, and enrollment nearly tripled. In addition, in 1967, the Penn State Milton S. Hershey Medical Center, a college of medicine and hospital, was established in Hershey with a $50 million gift from the Hershey Trust Company.

Modern era

In the 1970s, the university became a state-related institution. As such, it now belongs to the Commonwealth System of Higher Education. In 1975, the lyrics in Penn State’s alma mater song were revised to be gender-neutral in honor of International Women’s Year; the revised lyrics were taken from the posthumously-published autobiography of the writer of the original lyrics, Fred Lewis Pattee, and Professor Patricia Farrell acted as a spokesperson for those who wanted the change.

In 1989, the Pennsylvania College of Technology in Williamsport joined ranks with the university, and in 2000, so did the Dickinson School of Law. The university is now the largest in Pennsylvania. To offset the lack of funding due to the limited growth in state appropriations to Penn State, the university has concentrated its efforts on philanthropy.


Penn State is classified among “R1: Doctoral Universities – Very high research activity”. Over 10,000 students are enrolled in the university’s graduate school (including the law and medical schools), and over 70,000 degrees have been awarded since the school was founded in 1922.

Penn State’s research and development expenditure has been on the rise in recent years. For fiscal year 2013, according to institutional rankings of total research expenditures for science and engineering released by the National Science Foundation (US), Penn State stood second in the nation, behind only Johns Hopkins University (US) and tied with the Massachusetts Institute of Technology (US), in the number of fields in which it is ranked in the top ten. Overall, Penn State ranked 17th nationally in total research expenditures across the board. In 12 individual fields, however, the university achieved rankings in the top ten nationally. The fields and sub-fields in which Penn State ranked in the top ten are materials (1st), psychology (2nd), mechanical engineering (3rd), sociology (3rd), electrical engineering (4th), total engineering (5th), aerospace engineering (8th), computer science (8th), agricultural sciences (8th), civil engineering (9th), atmospheric sciences (9th), and earth sciences (9th). Moreover, in eleven of these fields, the university has repeated top-ten status every year since at least 2008. For fiscal year 2011, the National Science Foundation reported that Penn State had spent $794.846 million on R&D and ranked 15th among U.S. universities and colleges in R&D spending.

For the 2008–2009 fiscal year, Penn State was ranked ninth among U.S. universities by the National Science Foundation, with $753 million in research and development spending for science and engineering. During the 2015–2016 fiscal year, Penn State received $836 million in research expenditures.

The Applied Research Lab (ARL), located near the University Park campus, has been a research partner with the Department of Defense (US) since 1945 and conducts research primarily in support of the United States Navy. It is the largest component of Penn State’s research efforts statewide, with over 1,000 researchers and other staff members.

The Materials Research Institute was created to coordinate the highly diverse and growing materials activities across Penn State’s University Park campus. With more than 200 faculty in 15 departments, 4 colleges, and 2 Department of Defense research laboratories, MRI was designed to break down the academic walls that traditionally divide disciplines and enable faculty to collaborate across departmental and even college boundaries. MRI has become a model for this interdisciplinary approach to research, both within and outside the university. Dr. Richard E. Tressler was an international leader in the development of high-temperature materials. He pioneered high-temperature fiber testing and use, advanced instrumentation and test methodologies for thermostructural materials, and design and performance verification of ceramics and composites in high-temperature aerospace, industrial, and energy applications. He was founding director of the Center for Advanced Materials (CAM), which supported many faculty and students from the College of Earth and Mineral Science, the Eberly College of Science, the College of Engineering, the Materials Research Laboratory and the Applied Research Laboratories at Penn State on high-temperature materials. His vision for Interdisciplinary research played a key role in creating the Materials Research Institute, and the establishment of Penn State as an acknowledged leader among major universities in materials education and research.

The university was one of the founding members of the Worldwide Universities Network (WUN), a partnership that includes 17 research-led universities in the United States, Asia, and Europe. The network provides funding, facilitates collaboration between universities, and coordinates exchanges of faculty members and graduate students among institutions. Former Penn State president Graham Spanier is a former vice-chair of the WUN.

The Pennsylvania State University Libraries were ranked 14th among research libraries in North America in the 2003–2004 survey released by The Chronicle of Higher Education. The university’s library system began with a 1,500-book library in Old Main. In 2009, its holdings had grown to 5.2 million volumes, in addition to 500,000 maps, five million microforms, and 180,000 films and videos.

The university’s College of Information Sciences and Technology is the home of CiteSeerX, an open-access repository and search engine for scholarly publications. The university is also the host to the Radiation Science & Engineering Center, which houses the oldest operating university research reactor. Additionally, University Park houses the Graduate Program in Acoustics, the only freestanding acoustics program in the United States. The university also houses the Center for Medieval Studies, a program that was founded to research and study the European Middle Ages, and the Center for the Study of Higher Education (CSHE), one of the first centers established to research postsecondary education.