High-energy transient signals are most often determined to be gamma-ray burst events, but the recently-launched Einstein Probe has expanded astronomers’ ability to quickly respond to similar signals occurring at X-ray wavelengths. Now, a multi-wavelength study of EP240408a concludes that while many of the signal’s characteristics might lead to the conclusion that it is a gamma-ray burst, the non-detection at radio wavelengths precludes that possibility.
Recent News
Students Contribute to New Understanding of ‘Twinkling’ Pulsars
The flexible observing setup of the Green Bank Observatory’s 20-meter telescope enabled frequent, long-duration observations of eight pulsars, spanning two and a half years for a student-driven study carried out by students in the Pulsar Science Collaboratory program.
Double the Disks, Double the Discovery: New Insights into Planet Formation in DF Tau
Tucked away in a star-forming region in the Taurus constellation, a pair of circling stars are displaying some unexpected differences in the circumstellar disks of dust and gas that surround them. A new study led by researchers at Lowell Observatory, combining data from the Atacama Large Millimeter/submillimeter Array (ALMA) and Keck Observatory, has unveiled intriguing findings about planet formation in this binary star system, known as DF Tau, along with other systems in this region.
Asteroid Juno Seen Traveling Through Space in New ALMA Images and Animation
A series of images made with the Atacama Large Millimeter/submillimeter Array (ALMA) provides an unprecedented view of the surface of Juno, one of the largest members of our solar system’s main asteroid belt. Linked together into a brief animation, these high-resolution images show the asteroid rotating through space as it shines in millimeter-wavelength light.
“In contrast to optical telescopes, which capture the reflected light from the Sun, the new ALMA images show the actual millimeter-wavelength light emitted by the asteroid,” said Todd Hunter, an astronomer with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Va. A paper prepared by representatives of the entire international ALMA consortium detailing these observations was accepted for publication in the Astrophysical Journal, Letters.
According to Hunter: “By using ALMA to image the thermal glow from asteroids like Juno and other bodies in our solar system, astronomers will be able to study their shape, composition, and surface properties.”
The complete ALMA observation, which includes 10 separate images, documents about 60 percent of one rotation of the asteroid. It was conducted over the course of four hours on 19 October 2014 when Juno was approximately 295 million kilometers from Earth. In these images, the asteroid’s axis of rotation is tilted away from the Earth, revealing its southern hemisphere most prominently.
For this observation, ALMA achieved a resolution of 40 milliarcseconds, meaning that each “pixel” in the images is about 60 kilometers across, covering approximately one fourth of the surface of Juno. This resolution is a vast improvement over earlier observations made at similar wavelengths and is enough to clearly resolve the shape of the asteroid and potentially tease out prominent surface features.
Juno will make its next close approach to Earth in November 2018. Since the asteroid will be much closer than it was in the most recent observations, ALMA will be able to double its resolution, potentially revealing new details about this intriguing object. At approximately 240 kilometers across, Juno is among the largest members of the solar system’s main asteroid belt, but it is still only a few percent the mass of this region’s largest inhabitant: the dwarf planet Ceres, which is now playing host to NASA’s Dawn spacecraft.
“This new observation clearly demonstrates that ALMA will be a very powerful tool for studying asteroids,” said NRAO astronomer Arielle Moullet. “At its highest resolution, ALMA is powerful enough to resolve the surface of many asteroids.” Earlier models of Juno developed by studying its reflected light indicate that it has an oblong, or potato-like, shape with possibly minor indentations on its surface. The ALMA images seem to support this model.
Juno is one of five targets selected for study during the ALMA Long Baseline Campaign to test the telescope’s high-resolution capabilities, achieved when the antennas are at their greatest separation: up to 15 kilometers apart. The other targets include the protoplanetary disk HL Tau, the gravitationally lensed galaxy SDP.81, the star Mira, and quasar 3C138.
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The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
Contact: Charles Blue, Public Information Officer
(434) 296-0314; [email protected]
Recent News
NSF VLA Contributes Crucial Puzzle Piece to ‘Peculiar’ High Energy Transient
High-energy transient signals are most often determined to be gamma-ray burst events, but the recently-launched Einstein Probe has expanded astronomers’ ability to quickly respond to similar signals occurring at X-ray wavelengths. Now, a multi-wavelength study of EP240408a concludes that while many of the signal’s characteristics might lead to the conclusion that it is a gamma-ray burst, the non-detection at radio wavelengths precludes that possibility.
Students Contribute to New Understanding of ‘Twinkling’ Pulsars
The flexible observing setup of the Green Bank Observatory’s 20-meter telescope enabled frequent, long-duration observations of eight pulsars, spanning two and a half years for a student-driven study carried out by students in the Pulsar Science Collaboratory program.
Double the Disks, Double the Discovery: New Insights into Planet Formation in DF Tau
Tucked away in a star-forming region in the Taurus constellation, a pair of circling stars are displaying some unexpected differences in the circumstellar disks of dust and gas that surround them. A new study led by researchers at Lowell Observatory, combining data from the Atacama Large Millimeter/submillimeter Array (ALMA) and Keck Observatory, has unveiled intriguing findings about planet formation in this binary star system, known as DF Tau, along with other systems in this region.