Cosmicinsightz - Within The Cosmos

Wispy remains of a supernova explosion hide a possible ‘survivor.’ Of all the varieties of exploding stars, the ones called Type Ia are perhaps the most intriguing. Their predictable brightness lets astronomers measure the expansion of the universe, which led to the discovery of dark energy. Yet the cause of these supernovae remains a mystery. Do they happen when two white dwarf stars collide? Or does a single white dwarf gorge on gases stolen from a companion star until bursting? If the second theory is true, the normal star should survive. Astronomers used the Hubble Space Telescope to search the gauzy remains of a Type Ia supernova in a neighboring galaxy called the Large Magellanic Cloud. They found a sun-like star that showed signs of being associated with the supernova. Further investigations will be needed to learn if this star is truly the culprit behind a white dwarf’s fiery demise.

 This supernova remnant is located 160,000 light-years from Earth. The actual supernova remnant is the irregular shaped dust cloud, at the upper center of the image. The gas in the lower half of the image and the dense concentration of stars in the lower left are the outskirts of a star cluster.

Image credit: NASA, ESA and H.-Y. Chu (Academia Sinica, Taipei)

Remnants from a star that exploded thousands of years ago created a celestial abstract portrait, as captured in this NASA Hubble Space Telescope image of the Pencil Nebula.

Credit: NASA and The Hubble Heritage Team (STScI/AURA)

Arp 240, Galaxy Bridge 

What is a protostar?

The formation of stars begins with the collapse and fragmentation of molecular clouds into very dense clumps.  These clumps initially contain ~0.01 solar masses of material, but increase in mass as surrounding material is accumulated through accretion.  The temperature of the material also increases while the area over which it is spread decreases as gravitational contraction continues, forming a more stellar-like object in the process.  During this time, and up until hydrogen burning begins and it joins the main sequence, the object is known as a protostar.

This stage of stellar evolution may last for between 100,000 and 10 million years depending on the size of the star being formed. If the final result is a protostar with more than 0.08 solar masses, it will go on to begin hydrogen burning and will join the main sequence as a normal star.  For protostars with masses less than this, temperatures are not sufficient for hydrogen burning to begin and they become brown dwarf stars.

Protostars are enshrouded in gas and dust and are not detectable at visible wavelengths.  To study this very early stage of stellar evolution, astronomers must use infrared or microwave wavelengths.

Protostars are also known as Young Stellar Objects (YSOs).

Seven Worlds for TRAPPIST 1 : Seven worlds orbit the ultracool dwarf star TRAPPIST-1, a mere 40 light-years away. In May 2016 astronomers using the Transiting Planets and Planetesimals Small Telescope announced the discovery of three planets in the TRAPPIST-1 system. Just announced, additional confirmations and discoveries by the Spitzer Space Telescope and supporting ESO ground-based telescopes have increased the number of known planets to seven. The TRAPPIST-1 planets are likely all rocky and similar in size to Earth, the largest treasure trove of terrestrial planets ever detected around a single star. Because they orbit very close to their faint, tiny star they could also have regions where surface temperatures allow for the presence of liquid water, a key ingredient for life. Their tantalizing proximity to Earth makes them prime candidates for future telescopic explorations of the atmospheres of potentially habitable planets. All seven worlds appear in this artists illustration, an imagined view from a fictionally powerful telescope near planet Earth. Planet sizes and relative positions are drawn to scale for the Spitzer observations. The systems inner planets are transiting their dim, red, nearly Jupiter-sized parent star. via NASA

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