GLOWS is a non-imaging single-pixel Lyman-α An optical instrument used to measure the brightness of light within a specific range of wavelengths. It is commonly used in remote sensing techniques and can be configured to view the sky in a specific direction or sweep across a particular area. that observes the sky The number of specified items or components found in a defined space. of the The helioglow results from the interaction between interstellar neutral hydrogen atoms (ISN H), uncharged particles from outside our solar system, and a specific type of photon found in the Sun’s light emissions. These photons, called Lyman- α photons, are found in a narrow band of UV light that is invisible to human eyes. Occasionally, an ISN H atom that passed through the heliosphere boundary is excited by a Lyman-alpha photon, briefly boosting it into a higher energetic state. The atom can't be excited for very long, so it almost immediately drops back to the lowest energetic state, emitting a Lyman-α photon to take away this extra energy. The re-emitted photons form what we call the helioglow. Because UV light is invisible to human eyes, we can't see the helioglow, but we can detect it. The GLOWS instrument uses special sensors designed to collect and count the glowing particles that have a very specific amount of excited UV energy. to better understand the evolution of the A stream of charged particles, mostly protons and electrons, that escapes into the Sun's outer atmosphere at high speeds and streams out into the solar system in all directions. structure. The helioglow is formed by the interaction between interstellar neutral hydrogen (ISN H) and solar photons in a specific region called the Lyman-α waveband.
Photons enter the An instrument which is used to discover that something is present somewhere, or to measure how much of something there is. through a A device at the entrance to a sensor instrument that narrows a beam of particles or waves, such as light or energetic neutral atoms, into a more parallel or aligned stream. This helps improve the precision and accuracy of measurements or imaging by reducing the spread of the beam; the “gateway” into a sensor. with a baffle that restricts the photons to those only from The GLObal Solar Wind Structure (GLOWS) instrument investigates the structure of the solar wind and how it shifts during the solar cycle. GLOWS also investigates the distribution of the helioglow found in the extreme ultraviolet (EUV) range of the Sun’s light using a non-imaging single-pixel photometer that will collect and count Lyman-α photons found in the helioglow as IMAP spins on its axis.’ intended field of view (FOV). A spectral filter allows only photons found in the Lyman-α The distance from crest to crest or trough to trough of an electromagnetic wave or other wave. band into a channel A negatively charged elementary particle that normally resides outside (but is bound to) the nucleus of an atom. multiplier (CEM) detector that counts them. GLOWS’ FOV shifts with IMAP’s daily spin axis redirection, allowing for sequential observations of the structure of the solar wind from separate locations around the Sun. The Lyman-α The smallest possible particles of electromagnetic energy and therefore also the smallest possible particles of visible light. Photons have no mass or charge. They correspond to a single wavelength, but exist across the entire spectrum of electromagnetic radiation. counts from these observations can be used to build a more comprehensive picture of the solar wind structure and how it changes through the solar cycles.
GLOWS design and assembly is led by the Space Research Center of the Polish Academy of Sciences (CBK PAN).
The GLObal Solar Wind Structure (GLOWS) instrument prior to installation onto the IMAP spacecraft at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland.
Image Credit: NASA/Johns Hopkins APL/Princeton/Ed Whitman
