Researchers have long theorized that, like a comet, a "tail" trails the heliosphere, the giant bubble in which our solar system resides, as the heliosphere moves through interstellar space. The first IBEX images released in 2009 showed an unexpected ribbon of surprisingly high energetic neutral atom (ENA) emissions circling the upwind side of the solar system. With the collection of additional ENAs over the first year of observations, a structure dominated by lower energy ENAs emerged, which was preliminarily identified as the heliotail. However, it was quite small and appeared to be offset from the downwind direction, possibly because of interactions from the galaxy's external magnetic field.
As the next two years of IBEX data filled in the observational hole in the downwind direction, researchers found a second tail region to the side of the previously identified one. The IBEX team reoriented the IBEX maps and two similar, low-energy ENA structures became clearly visible straddling the downwind direction of the heliosphere, indicating structures that better resemble "lobes" than a single unified tail.
"We chose the term 'lobes' very carefully," says Dr. Dave McComas, IBEX principal investigator and assistant vice president of the Space Science and Engineering Division at Southwest Research Institute. "It may well be that these are separate structures bent back toward the downwind direction. However, we can't say that for certain with the data we have today."
The team adopted the nautical terms port and starboard to distinguish the lobes, as the heliosphere is the "vessel" that transports our solar system throughout the galaxy.
IBEX data show the heliotail is the region where the Sun's million mile per hour solar wind flows down and ultimately escapes the heliosphere, slowly evaporating because of charge exchange. The slow solar wind heads down the tail in the port and starboard lobes at low- and mid-latitudes and, at least around the Sun's minimum in solar activity, fast solar wind flows down it at high northern and southern latitudes.
"We're seeing a heliotail that's much flatter and broader than expected, with a slight tilt," says McComas. "Imagine sitting on a beach ball. The ball gets flattened by the external forces and its cross section is oval instead of circular. That's the effect the external magnetic field appears to be having on the heliotail."
The IBEX spacecraft uses two novel ENA cameras to image and map the heliosphere's global interaction, providing the first global views and new knowledge about our solar system's interaction with interstellar space.
"We often think we know what we're going to study in science, but the work sometimes takes us in unexpected directions," says McComas. "That was certainly the case with this study, which started by simply trying to better quantify the small structure incorrectly identified as an 'offset heliotail.' The heliotail we found was much bigger and very different from what we expected."
The paper, "The heliotail revealed by IBEX," by D.J. McComas, M.A. Dayeh, H.O. Funsten, G. Livadiotis, and N.A. Schwadron, was published today in the Astrophysical Journal.
IBEX is part of NASA's series of low-cost, rapidly developed Small Explorer space missions. Southwest Research Institute in San Antonio leads the IBEX mission with teams of national and international partners. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the Explorers Program for NASA's Science Mission Directorate in Washington.
Editors: Images to accompany this story are available at http://svs.gsfc.nasa.gov/vis/a010000/a011300/a011301/ .
Maria Martinez | EurekAlert!
Scientists propose synestia, a new type of planetary object
23.05.2017 | University of California - Davis
Turmoil in sluggish electrons’ existence
23.05.2017 | Max-Planck-Institut für Quantenoptik
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Physics and Astronomy
23.05.2017 | Life Sciences
23.05.2017 | Medical Engineering