For Yous Data - The Cygnus Loop

The Cygnus Loop (also known every bit the Veil Nebula) is a supernova remnant, the detritus of the explosive expiry of a massive star almost 10 to xx yard years ago. Detailed modeling of its spectacular filamentary shape suggests that the explosion occurred within an interstellar cavity created past times the progenitor star.

A composite icon of the Cygnus Loop (Veil) Nebula, the detritus of a supernova explosion,
as seen inwards X-ray (blue), UV (white), in addition to 12 in addition to 22 μm infrared information (blue in addition to red, respectively)
with the ROSAT, GALEX in addition to WISE missions. Astronomers accept used novel astrometric information
from the GAIA mission to make upwards one's hear the distance to the nebula: almost 2420 light-years
[Credit: NASA; Fesen et al. 2018]

As is mutual inwards astronomy, many of the precise physical properties of the object are rendered uncertain past times the dubiety of its distance. For decades scientists used a value of almost 2500 light-years based on analyses of its gas motions past times Hubble inwards 1937 in addition to Minkowski inwards 1958. Many recent distance estimates accept varied over a broad arrive at to a greater extent than oft than non consistent alongside this one, precisely the most cited value is a 2005 touchstone of betwixt 1500 in addition to 2100 light-years.

During the past times ii decades astronomers accept tried to pivot downward the distance past times measuring the distances to stars either behind or within the nebula every bit determined past times seeing absorption lines from the nebula inwards their spectra precisely the distances to those stars are inwards plough likewise uncertain, in addition to parallax measurements of some of the stellar distances accept too been unreliable. Efforts accept too been made late to stair out the distance using the motions of the nebular gas directly, alongside published estimates suggesting a theatre distance less than 2600 light-years in addition to consistent alongside the sometime value of 2500 light-years.

The Gaia satellite has been making rattling precise measurements of stellar parallaxes, in addition to the most recent catalogs accept at nowadays been released. CfA astronomer John Raymond joined alongside iv colleagues to apply the Gaia information to the occupation of the Cygnus Loop distance past times looking for absorption signatures from the gas inwards the ii dozen stellar spectra, thereby constraining the stars every bit beingness foreground or background objects. Their result: 2420 light-years to the key role of the nebula, alongside a 3.4% uncertainty. They too identified a star whose current of air is interacting alongside the supernova remnant.

The novel distance trial has several of import implications. It agency that the supernova that created the Loop had less release energy than previously idea past times perchance every bit much every bit a component subdivision of iv (about every bit much release energy every bit the electrical current Sunday would emit inwards vi billion years). It too agency that the nebula is likely aspherical inwards shape alongside the eastern beingness limb beingness closer to us than the western side in addition to alongside a diameter of almost ane hundred in addition to xx light-years.

The written report is published inwards Monthly Notices of the Royal Astronomical Society.

Source: Harvard-Smithsonian Center for Astrophysics [November 26, 2018]


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