Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23

Details Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23 Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsh11b1919v&link_type=abstract

American Geophysical Union, Fall Meeting 2011, abstract #SH11B-1919

Astronomy and Astrophysics

Astrophysics

[7536] Solar Physics, Astrophysics, And Astronomy / Solar Activity Cycle, [7549] Solar Physics, Astrophysics, And Astronomy / Ultraviolet Emissions

Scientific paper

The interplanetary hydrogen (IPH), a population of neutrals that fill the space between planets inside the heliosphere, carries the signature of the interstellar medium (ISM) and the heliospheric interface. As the ionized component of the incoming ISM deflects at the heliopause, charge exchange reactions decelerate the bulk motion of the neutrals that penetrate the heliosphere. Inside the heliosphere, the IPH bulk velocity is further affected by solar gravity, radiation pressure, and ionization processes, with the latter two processes dependent on solar activity. Solar cycle 23 provided the first partial temporal map of the IPH velocity, including measurements from the Hubble Space Telescope (HST) spectrometers (Goddard High Resolution Spectrograph (GHRS) and Space Telescope Imaging Spectrograph (STIS)) and the Solar and Heliospheric Observatory/Solar Wind ANisotropies (SWAN) instrument. We present an updated analysis of IPH velocity measurements from GHRS and STIS, and compare these results with those of SWAN and two different time-dependent models. Our reanalysis of STIS data reveals a significant change in IPH velocity relative to earlier reports, because of the contamination by geocoronal oxygen that was not accounted for. As a consequence, it corrects the discrepancy with SWAN data near solar maximum (2001) and we now find that all data can be fit by the existing models to within 1σ, with the exception of SWAN observations taken at solar minimum (1997/1998). We suggest that this discrepancy at solar minimum could be due to an indirect effect of the local interstellar magnetic field, which should be included in future modeling efforts. There may be extra features as the geocoronal deuterium or a possible Fermi effect from the heliospheric interface but the diagnostic is difficult because the resolution of these observations is limited. We conclude that the current data lack the temporal coverage and/or precision necessary to determine the detailed characteristics of the solar cycle dependence. Hence, new observations are merited and regular Ly-α measurements will be extremely helpful to constrain the problem of the heliospheric interface.

Affiliated with

Also associated with

No associations

Rating

Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-876297