Scientists Make First-Ever Observations Of Comet's Demise Deep Inside Solar Atmosphere
In a paper to be published tomorrow in the journal Science, for the first time ever scientists at the Lockheed Martin Solar and Astrophysics Laboratory (LMSAL) at the Advanced Technology Centre (ATC) in Palo Alto, and collaborators at other institutions, have reported observations and analysis of the final death throes of a comet, as it passed across the face of the Sun on July 6, 2011, to vanish in flight. Read more
Title: Destruction of Sun-Grazing Comet C/2011 N3 (SOHO) Within the Low Solar Corona Authors: C. J. Schrijver, J. C. Brown, K. Battams, P. Saint-Hilaire, W. Liu, H. Hudson, W. D. Pesnell
Observations of comets in Sun-grazing orbits that survive solar insolation long enough to penetrate into the Sun's inner corona provide information on the solar atmosphere and magnetic field as well as on the makeup of the comet. On 6 July 2011, the Solar Dynamics Observatory (SDO) observed the demise of comet C/2011 N3 (SOHO) within the low solar corona in five wavelength bands in the extreme ultraviolet (EUV). The comet penetrated to within 0.146 solar radius (~100,000 kilometres) of the solar surface before its EUV signal disappeared. Before that, material released into the coma - at first seen in absorption - formed a variable EUV-bright tail. During the final 10 minutes of observation by SDO's Atmospheric Imaging Assembly, ~6 x 10^8 to 6 x 10^10 grams of total mass was lost (corresponding to an effective nucleus diameter of ~10 to 50 meters), as estimated from the tail's deceleration due to interaction with the surrounding coronal material; the EUV absorption by the comet and the brightness of the tail suggest that the mass was at the high end of this range. These observations provide evidence that the nucleus had broken up into a family of fragments, resulting in accelerated sublimation in the Sun's intense radiation field.
Comet C/2011 N3 (SOHO) was discovered by the SOHO satellite on the 4th July, 2011. The preliminary orbital elements of the comet indicate a perihelion passage on the 6th July, 2011, at a distance of 0.005 AU from the Sun.
On the evening of Tuesday, July 5, a comet flew into the sun. Such comets are not unusual, and they're called "sungrazers" since they come so close to the star that it is believed they evaporate and disappear. However, no one has actually seen the end of that journey, since the comets are best seen in cameras from SOHO (SOlar and Heliospheric Observatory) that block out the bright disk of the sun itself. But this was different. For the first time ever, SDO (Solar Dynamics Observatory) captured a 20-minute movie of the comet streaking directly in front of the sun. It's not immediately obvious, but if you watch the movie closely, you'll see a line of light appear in the right and move across to the left. Read more