Sunday, April 1, 2018

Something "new"


 Nova

N CMa 2018


At left of the two pictures below is the pertinent cropped section of the nova image I obtained using a remote-controlled Slooh.com telescope. For reference, I reproduced a section of the map produced by Robert Conrad, using the American Association of Variable Star Observers AAVSO Variable Star Plotter regarding the AAVSO Alert Notice 627 in relation to the discovery of the nova. The nova was discovered in Japan on March 24 by Yuji Nakamura in Japan using a 4" photographic reflector telescope (called an astrograph). Robert Conrad, who is our Director of Observing at our Vancouver RASC centre, and who diligently digs out and observes new events in the sky, notified our observers about this. Spectroscopic observations, using larger, professional telescopes, classified this nova as the classical type.


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 Left: Image of Nova      Right: A section of AAVSO map of Nova location.



Here is an excerpt from Wikipedia:

Classical nova eruptions are the most common type of nova. They are likely created in a close binary star system consisting of a white dwarf and either a main sequence, sub-giant, or red giant star. When the orbital period falls in the range of several days to one day, the white dwarf is close enough to its companion star to start drawing accreted matter onto the surface of the white dwarf, which creates a dense but shallow atmosphere. This atmosphere is mostly hydrogen and is thermally heated by the hot white dwarf, which eventually reaches a critical temperature causing rapid runaway ignition by fusion. From the dramatic and sudden energies created, the now hydrogen-burnt atmosphere is then dramatically expelled into interstellar space, and its brightened envelope is seen as the visible light created from the nova event, and previously was mistaken as a "new" star. A few novae produce short-lived nova remnants,[1] lasting for perhaps several centuries. Recurrent nova processes are the same as the classical nova, except that the fusion ignition may be repetitive because the companion star can again feed the dense atmosphere of the white dwarf.

Novae most often occur in the sky along the path of the Milky Way, especially near the observed galactic centre in Sagittarius; however, they can appear anywhere in the sky. They occur far more frequently than galactic supernovae, averaging about ten per year. Most are found telescopically, perhaps only one every year to eighteen months reaching naked-eye visibility. Novae reaching first or second magnitude occur only several times per century.

More details can be obtained by linking to https://en.wikipedia.org/wiki/Nova .

You can't be bored if you are interested in astronomy. There is always something new in the sky.







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