Voyager Enters Final Frontier Of Solar System Options

[Guest_Sunspot_*]

http://planetary.org/news/2005/voyager-upd...ation_0524.html

Voyager 1, the most distant human-made object in space, has crossed the termination shock, the last major threshold in the solar system, team members announced today at the annual American Geophysical Union (AGU) meeting in New Orleans, Louisiana.

[ljk4-1]

Astrophysics, abstract
astro-ph/0603318

From: Merav Opher [view email]

Date: Mon, 13 Mar 2006 19:30:59 GMT (539kb)

Effects of a Local Interstellar Magnetic Field on Voyager 1 and 2 Observations

Authors: Merav Opher, Edward C. Stone, Paulett C. Liewer

Comments: 12 pages, 5 figures

Journal-ref: Astrophysical Journal Letters v.640, 71, 2006

We show that that an interstellar magnetic field can produce a north/south asymmetry in solar wind termination shock. Using Voyager 1 and 2 measurements, we suggest that the angle $\alpha$ between the interstellar wind velocity and magnetic field is $30^{\circ} < \alpha < 60^{\circ}$. The distortion of the shock is such that termination shock particles could stream outward along the spiral interplanetary magnetic field connecting Voyager 1 to the shock when the spacecraft was within $\sim 2~AU$ of the shock. The shock distortion is larger in the southern hemisphere, and Voyager 2 could be connected to the shock when it is within $\sim 5~AU$ of the shock, but with particles from the shock streaming inward along the field. Tighter constraints on the interstellar magnetic field should be possible when Voyager 2 crosses the shock in the next several years.

http://fr.arxiv.org/abs/astro-ph/0603318

[dilo]

From updated solar wind speed diagram, Voyager-2 experienced a repentine increase (more than 100 Km/s) at the end of February/beginning of March.
In my understanding, transition through termination shock should produce a dramatic wind speed decrease, so this is not the case... Anyway still intriguing, because even if in the past Voyager-2 already observed speed close to 500 Km/s, now increase seems more repentine and appear associated to one of the largest ions density spikes ever observed by the spacecraft...
Any suggestion?

[dilo]

Something is definitely happening around Voyager-2!
Last nucleon data shows that, after 10 months of caothic behavior, density dropped to very low levels; in the meantime, wind speed stopped the regular descent (after the step-up previously noticed) and started to go up and down on a hourly scale (density and velocity seems to have a complementary behaviour...).
I do not recall what exactly happened to Voyager-1 density data (any help?), but I strongly suspect termination shock is very close... or already passed!