23 Oct 2013

Dazzling comet ISON may be dying, says study

Comet ISON photographed by the Hubble telescope.File photo: NASA/Reuters
Comet ISON photographed by the Hubble telescope.File photo: NASA/Reuters
Comet ISON – predicted to be one of the brightest comets of the century – may actually be disintegrating, according to a new study.
Astronomer Ignacio Ferrin, from the Universidad de Antioquia, analysed the most recent observational data of Comet ISON and has identified clear signatures of what he has called an “impending demise” of the comet.
The so-called light-curve of the comet shows features previously observed in disintegrating comets.
Despite the generalised scepticism and claims about the fact that the rumours of comet ISON “fizzling” were greatly exaggerated, the comet is still showing an unexpected behaviour that cometary specialists are fighting to explain.
“The light curve of the comet exhibited a slowdown event characterised by a constant brightness with no indication of a brightness increase tendency,” he said.
This slowdown began around January 13, 2013, and it continued up to the latest available observations at the end of September, this year, Ferrin said.
The brightness has remained practically constant for more than 270 days or 9 months, a behaviour without any precedent in cometary astronomy.
These evidences have led Ferrin to conclude that it is probably that the “comet is dying“.
In a recent letter posted to Cornell University arXiv preprints repository, Ferrin presented and discussed what he identified as a peculiar photometric signature previously observed in disintegrating comets.
“When I saw this signature I immediately went to my database of comet light curves, and found that two comets had also presented this signature: Comet C/1996 Q1 Tabur and comet C/2002 O4 Honig; to my surprise these two comets had vanished turning off or disintegrating,” he said.PTI

Courtesy with: THE HINDU

Is the ‘Christmas Comet’ cracking up?

photo: Reuters
photo: Reuters
An incoming comet that skygazers had hoped would provide one of the greatest celestial shows of the century, could be a fizzle.
So say astronomers tracking the eagerly-awaited Comet ISON as it races to a searing encounter with the Sun.


Formally known as C/2012 S1 (ISON), the comet was spotted by a pair of hard-working amateur Russian astronomers on September 21, 2012.
It is called ISON because they used a telescope called the International Scientific Optical Network near Kislovodsk, in the northern Caucasus.


After the discovery was validated by the International Astronomical Union (IAU), interest in the enigmatic wanderer became huge.
Calculations showed that after looping around the Sun, the comet would become a blaze of glory towards the end of the year — a timing that gave it the tabloid title of “Christmas Comet” or even “Comet of the Century.”


Fears are multiplying that the great show will be cancelled.
Light signatures from ISON, which has just streaked past Mars, indicate the comet is about to break up, says astrophysicist Ignacio Ferrin. “This disintegration will take place before it reaches perihelion,” Ferrin said. Perihelion is an orbit’s closest point to the Sun, which ISON is supposed to reach on November 28.
He explained that comets typically brighten as they get closer to the Sun, crossing a temperature threshold that causes their icy surfaces to evaporate, depositing water vapour, other gases and dust in their wake.
But, said Ferrin, the light curve from ISON slowed down and then remained practically constant, with no sign of greater brightness, as it raced forward.
This is a signature that matches four previous comets that have broken up catastrophically, he said.AFP

Courtesy with: THE HINDU

Popularising astronomy with passing of comet Ison

Delegates familiarising themselves with the comet Ison in a workshop held at Lycee Françoise in Puducherry on Saturday.
Delegates familiarising themselves with the comet Ison in a workshop held at Lycee Françoise in Puducherry on Saturday.
The Pondicherry Science Forum has taken up a three month project to improve community’s knowledge on astronomy through the comet Ison, which is scheduled to move closest to the sun at the end of November.
During a two-day workshop, ‘Eyes on Ison’ the delegates, most of whom were school teachers, had been exposed to presentations, demonstrations, talks and even real time tracking of the comet Ison.
Through the comet, they also educated the delegates on the solar system and various aspects of astronomy, State coordinator of the PSF Hemavathy told The Hindu .
The main activities were scheduled for late night on Friday and early morning on Saturday. The participants then learnt about the night sky, and also managed to locate the comet, which is currently near Mars.
They were also given briefings on the daytime sky. Now, the project would spread to the various communes, where the delegates of the workshop were divided into teams, and each team will submit a proposal on what they can do in their commune to raise awareness and involve the community for the passing of Ison.
They would also visit various schools armed with resource material on the comet and astronomy in general to teach the students.
“The coming of Ison is extremely important since this is the first time it will be crossing the solar system. Since it was discovered when it was at the edge of the solar system, there has been a lot of time to study the comet, so a lot of valuable information has been gleaned. It is important that the people of Puducherry, especially school students, understand the importance of the comet and are able to appreciate it in its true splendour by the time it achieves perihelion (near the sun),” she said.

Courtesy with: THE HINDU