In their work, the scientists used a filtering algorithm when processing image data.So the
Recall that the Hubble constant is a coefficient included in Hubble's law, which relatesthe distance to the extragalactic object with the rate of its receding.
As you know, a planetary nebula is an astronomical object that is a shell of ionized gas around the central star, a white dwarf.It is formed by the ejection of the outer layers of a red giant or supergiant with a mass of0.8 to 8 solar at the final stage of its evolution.
In contrast to the continuous spectrum of a star, ions from certain elements in this gaseous envelope, such as hydrogen, oxygen, helium, and neon, emit Special optical filters tuned to these wavelengths canThe nearest object of this type in the Milky Way is the Helical Line Nebula, 650 light-years from Earth .
As the distance to the planetary nebula increases, the apparent diameter of the image decreases, and the total apparent brightness decreases in proportion to the square of the distance.In the nearby Andromeda galaxy, the Spiral Nebula will be visible only as a dot, and its apparent brightness will be 15 million times fainter.However , with today's large telescopes and long exposure times, such objects can be imaged and measured using optical filters or image spectroscopy.
AIP research team with colleaguesfrom the United States has developed a method for using MUSE to isolate and accurately measure extremely weak signals from planetary nebulae in distant galaxies with high sensitivity. This is where a particularly efficient filtering algorithm plays an important role in image data processing. Archival ESO data is available for the ring galaxy NGC 474, based on two very deep MUSE exposures, each with an observation time of 5 hours. Scientists have published the result of data processing: after applying the filtering algorithm, 15 extremely faint planetary nebulae became visible.
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Hubble's Law (the law of universal recession of galaxies) is a cosmological law that describes the expansion of the Universe.