Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction
We present general considerations regarding the derivation of the radial distances of coronal mass ejections (CMEs) from elongation angle measurements such as those provided by SECCHI and SMEI, focusing on measurements in the Heliospheric Imager 2 (HI-2) field of view (i.e. past 0.3 AU). This stu...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2009-09-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/27/3479/2009/angeo-27-3479-2009.pdf |
| _version_ | 1819157630320377856 |
|---|---|
| author | N. Lugaz A. Vourlidas I. I. Roussev |
| author_facet | N. Lugaz A. Vourlidas I. I. Roussev |
| author_sort | N. Lugaz |
| collection | DOAJ |
| description | We present general considerations regarding the derivation of the radial
distances of coronal mass ejections (CMEs) from elongation angle measurements
such as those provided by SECCHI and SMEI, focusing on measurements in the
Heliospheric Imager 2 (HI-2) field of view (i.e. past 0.3 AU). This study is
based on a three-dimensional (3-D) magneto-hydrodynamics (MHD) simulation of
two CMEs observed by SECCHI on 24–27 January 2007. Having a 3-D simulation
with synthetic HI images, we are able to compare the two basic methods used
to derive CME positions from elongation angles, the so-called "Point-P" and
"Fixed-φ" approximations. We confirm, following similar works, that
both methods, while valid in the most inner heliosphere, yield increasingly
large errors in HI-2 field of view for fast and wide CMEs. Using a simple
model of a CME as an expanding self-similar sphere, we derive an analytical
relationship between elongation angles and radial distances for wide CMEs.
This relationship is simply the harmonic mean of the "Point-P" and
"Fixed-φ" approximations and it is aimed at complementing 3-D fitting
of CMEs by cone models or flux rope shapes. It proves better at getting the
kinematics of the simulated CME right when we compare the results of our
line-of-sights to the MHD simulation. Based on this approximation, we
re-analyze the J-maps (time-elongation maps) in 26–27 January 2007 and
present the first observational evidence that the merging of CMEs is
associated with a momentum exchange from the faster ejection to the slower
one due to the propagation of the shock wave associated with the fast
eruption through the slow eruption. |
| first_indexed | 2024-12-22T16:11:49Z |
| format | Article |
| id | doaj.art-b77d4d5d1a614a21931afc8244897dde |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-22T16:11:49Z |
| publishDate | 2009-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-b77d4d5d1a614a21931afc8244897dde2022-12-21T18:20:29ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762009-09-01273479348810.5194/angeo-27-3479-2009Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interactionN. Lugaz0A. Vourlidas1I. I. Roussev2Institute for Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI, 96822, USACode 7663, Naval Research Laboratory, Washington, D.C., 20375, USAInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI, 96822, USAWe present general considerations regarding the derivation of the radial distances of coronal mass ejections (CMEs) from elongation angle measurements such as those provided by SECCHI and SMEI, focusing on measurements in the Heliospheric Imager 2 (HI-2) field of view (i.e. past 0.3 AU). This study is based on a three-dimensional (3-D) magneto-hydrodynamics (MHD) simulation of two CMEs observed by SECCHI on 24–27 January 2007. Having a 3-D simulation with synthetic HI images, we are able to compare the two basic methods used to derive CME positions from elongation angles, the so-called "Point-P" and "Fixed-φ" approximations. We confirm, following similar works, that both methods, while valid in the most inner heliosphere, yield increasingly large errors in HI-2 field of view for fast and wide CMEs. Using a simple model of a CME as an expanding self-similar sphere, we derive an analytical relationship between elongation angles and radial distances for wide CMEs. This relationship is simply the harmonic mean of the "Point-P" and "Fixed-φ" approximations and it is aimed at complementing 3-D fitting of CMEs by cone models or flux rope shapes. It proves better at getting the kinematics of the simulated CME right when we compare the results of our line-of-sights to the MHD simulation. Based on this approximation, we re-analyze the J-maps (time-elongation maps) in 26–27 January 2007 and present the first observational evidence that the merging of CMEs is associated with a momentum exchange from the faster ejection to the slower one due to the propagation of the shock wave associated with the fast eruption through the slow eruption.https://www.ann-geophys.net/27/3479/2009/angeo-27-3479-2009.pdf |
| spellingShingle | N. Lugaz A. Vourlidas I. I. Roussev Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction Annales Geophysicae |
| title | Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction |
| title_full | Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction |
| title_fullStr | Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction |
| title_full_unstemmed | Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction |
| title_short | Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction |
| title_sort | deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere ndash application to cme cme interaction |
| url | https://www.ann-geophys.net/27/3479/2009/angeo-27-3479-2009.pdf |
| work_keys_str_mv | AT nlugaz derivingtheradialdistancesofwidecoronalmassejectionsfromelongationmeasurementsintheheliospherendashapplicationtocmecmeinteraction AT avourlidas derivingtheradialdistancesofwidecoronalmassejectionsfromelongationmeasurementsintheheliospherendashapplicationtocmecmeinteraction AT iiroussev derivingtheradialdistancesofwidecoronalmassejectionsfromelongationmeasurementsintheheliospherendashapplicationtocmecmeinteraction |