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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20170411T123000
DTEND;TZID=Atlantic/Canary:20170411T133000
UID:iactalks-1026
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/1026
CREATED:2017-04-11T12:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Solar core rotation from asymptotic g modes
DESCRIPTION:Solar core rotation from asymptotic g modes\nDr. Eric Fossat\n\
 nHelioseismology is about 40 years old, still a young science. It has been
  a tremendous success providing many more results than initially expected,
  including those coming from Izana of course. Now we really know a lot of 
 the solar internal structure and rotation.However, one important parameter
  has still resisted to this investigation, the solar core rotation, which 
 is not accessible to acoustic modes of oscillation, and helioseismlogy suc
 cesses have all been obtained from acoustic modes. The reason is simple: t
 he second type of seismic oscillations, called g modes (g for gravity, as 
 the waves on the sea) are confined in the deepest layers of the Sun, while
  the observers are staying outside. These g modes that contain the informa
 tion on all properties of the solar core have never been convincingly dete
 cted despite many efforts and attempts during the last forty years.We have
  used a differential parameter of the acoustic modes, carefully selecteded
  to have a maximum sensitivity to the deepest layers and a minimum sensiti
 vity to the surface layers, to look for its possible modulation produced b
 y periodic motions in the solar core. The frequencies possibly accessible 
 are very low, they correspond to periods between about half a day and two 
 days. The advantage is that in this very low frequency range, if g modes e
 xist, they must follow an asymptotic behaviour that makes possible a colle
 ctive detection. Using a long data set (16.5 years) from the GOLF instrume
 nt onboard  the SOHO space mission, the result is the success of this
  search, and I will present you these asymptotic parameters, including the
  measurement of the core rotation within less than 1 percent uncertainty.
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