Evolution of an Eruptive Prominence from the Corona to Interplanetary Space

(Solar Orbiter Nugget #69 by B. Zhuang¹, N. Lugaz¹, B. E. Wood², C. R. Braga³, M. Temmer⁴, T. Gou⁵, P. Hess², S. B. Shaik^2,6, C. Mac Cormack^7,8, and X. Li​⁹​)

1. Introduction

Understanding the location and evolution of the cool dense prominence in relation to the large-scale structure of coronal mass ejections (CMEs) is critical to distinguish between different CME initiation mechanisms and to further deepen our understanding of CME evolution through the heliosphere [e.g., 1-3].

Unlike large-scale CMEs, eruptive prominences that can be clearly tracked in interplanetary space are rare [e.g., 1,4].

Combining remote observations of extreme-ultraviolet (EUV) images and white-light (WL) coronagraphs and heliospheric imagers (HIs) obtained from SDO, SOHO, STEREO-A, and Solar Orbiter, we present an analysis of the continuous tracking from the corona to interplanetary space (to distances of about 1 AU) of the substructures of a CME associated with a prominence that erupted on 2022 September 23.

2. Observations

The CME of interest erupted at around 13:00 UT on 2022 September 23, based on EUV observations (Figure 1). The CME was observed by Solar Orbiter (SO), STEREO-A, and telescopes near Earth. STEREO-A was east of Earth, while SO was located at 0.49 au and separated by 165° west of Earth. Both the global CME structure and its associated prominence propagated approximately along the longitude of 90° west (indicated by the gray arrow in Figure 1), based on the graduated cylindrical model (GCS; [5]) and triangulation methods [6,7].

Figure 1: Spacecraft locations and prominence observations in EUV and WL images. In the top left panel, the red solid and dashed straight lines indicate the FOVs of STEREO-A/HI1 and HI2, respectively. The green dashed lines indicate SoloHI’s FOV. The gray arrow indicates the longitude of the CME propagation direction of 90° west from Earth.

The propagation of the CME and its substructures in interplanetary space were observed by STEREO-A/HIs [8] and Solar Orbiter Heliospheric Imager (SoloHI; [9]), as shown in Figures 2 and 3. Having a heliocentric distance smaller than 1 au enhances SoloHI’s spatial resolution and enables observations of more detailed CME substructures [e.g., 10]. In Figure 2, the prominence remained bright and compact for approximately one day after its eruption and maintained a similar morphology for about 14 hours, compared to its appearance in LASCO/C3 and STEREO-A/COR2 at around 17:40 UT on 2022 September 23 (the right part of Figure 1).

Figure 2: Running-difference HI observations of the 2022 September 23 CME obtained from STEREO-A/HI1 (left) and SoloHI (right). The CME and prominence fronts are outlined by the red and blue curves, respectively.

When the CME propagated to an elongation of about 20° in the STEREO-A/HI1 FOV, a nearly vertical dark ridge appeared and traveled along with the CME to the HI2 FOV (indicated by the white dashed curve in Figure 3). The dark ridge finally passed over the prominence (see the bottom right panel of Figure 3), during which the prominence was seen to be tilted and lagging behind the CME dark ridge but remained bright and compact. The CME front was seen to be distorted during its propagation (e.g., see the bottom left panel of Figure 2). As the CME propagated further, the distortion became more evident, and two bright fronts (a sharp inner one and a fuzzy outer one) appeared and were separated gradually. Multiple apparent fronts in HI images are also called “ghost” fronts [e.g., 11]. The appearance of the two fronts could be attributed to three different factors: (a) distortion due to interaction; (b) preexisting distortion; or (c) the difference between the leading edge and the CME sheath region.

Figure 3: Running-difference processed STEREO-A HI observations of the 2022 September 23 CME.

CME Kinematic Evolution

Kinematic evolutions from the corona to interplanetary space of the CME substructures are shown in Figure 4. The fixed-phi method [e.g., 12] and the self-similar expansion (SSE) method [13] are used to convert the measured elongations of the prominence and other CME substructures (e.g., front) to heliocentric distances.

Both the CME and prominence fronts showed an acceleration in the (high) corona, with the CME front velocity increasing to about 758 km/s when the CME reached about 26R_sun . After that, the CME front showed a deceleration, while the prominence propagated at an approximately constant velocity of 600 km/s.

The radial size between the CME front and the prominence front increased monotonically during the CME propagation before the occurrence of the front distortion. Considering that the prominence was positioned at (near) the CME bottom [e.g., 1], the radial size evolution is extrapolated outward starting from the estimate in the corona and using a power-law function with two power-law indices (alpha=1 indicating an SSE of the CME, and alpha=0.78 obtained from past statistics). The extrapolation with alpha=0.78  matches well with the measured radial size, indicating a non-SSE for the CME. However, under the alternative scenario that the CME experiences different expansion mechanisms at different heliocentric distances [14], with a self-similar and stronger expansion occurring close to the Sun [15], this consistency may instead suggest that the prominence moves toward the CME center during its propagation.

Figure 4: Kinematic and radial size evolution of the CME substructures along with the front distance. The top panel shows the velocity of the CME front and prominence front along with the front distance. The bottom panels show the radial size evolution along with the CME front distance. The two curves indicate the power-law forward-extrapolated radial sizes based on the CME radial size estimate in the corona. The vertical dashed line indicates the distance of 60Rsun  (0.28 au), at which the two bright fronts first appeared. The appearance of the two fronts on the right of the vertical prevents accurate measurements of the velocity and radial size evolutions, and thus the data points of the CME front on the right of the vertical line are shown with thinner symbols.

Conclusions

Combining STEREO-A/HIs and SoloHI, an eruptive prominence was continuously tracked in interplanetary space. The prominence remained bright and compact for more than 3 days after its eruption, reaching a distance of about 1 au. The persistence of a prominence observed in interplanetary space is a very unusual occurrence during the decade and a half since STEREO’s launch.

The prominence propagation relative to the global CME structure is crucial for understanding its evolution, e.g., whether the prominence propagates with the CME (considering that the prominence has been fully ionized in the high corona; [16]) or independently of it [2,4]. For this case, with the first 0.28 au (60R_sun), the consistent evolution of the kinematics of the CME front and that of the prominence suggests that the prominence propagation was governed by the CME dynamics. Beyond that distance, the prominence’s constant velocity, along with observations of its tilt and the passage of a dark ridge associated with the CME rear, indicate that the prominence may start propagating independently of the CME farther from the Sun. Together, these results suggest that both scenarios (the prominence being tied to and propagating independently of the CME) are valid, but within different distance ranges. The location of the transition may depend on the specific case, and the generality of this finding requires further investigation, for example using STEREO/HIs, SoloHI, PUNCH, and the planned HIs on Vigil.

This nugget is based on the following paper: Zhuang et al. 2025, ApJ, 990:18, 10.3847/1538-4357/adf2a9

Acknowledgements

We thank the mission teams for the ready availability of their data. B.Z. acknowledges NASA grant No. 80NSSC23K1057. B.Z. and N.L. acknowledge NASA grant Nos. 80NSSC20K0431 and 80NSSC24K1245, and NSF grant AGS-2301382. P.H. and B.W. acknowledge support from the Office of Naval Research. C.R.B. acknowledges NASA grant Nos. 80NSSC22K1028, 80NSSC23K0412, and 80NSSC24K1252. S.B.S. acknowledges the support from George Mason University via the NRL contract N00173-23-2-C603. SoloHI was designed, built, and is now operated by the US Naval Research Laboratory, with support from the NASA Heliophysics Division and the Solar Orbiter Collaboration Office under DPR NNG09EK11I.

Affiliations

1 Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA

2 Naval Research Laboratory, Space Science Division, Washington, DC 20375, USA

3 Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA

4 Institute of Physics, University of Graz, A-8010 Graz, Austria

5 Center for Astrophysics | Harvard & Smithsonian, Cambridge, MA 02138, USA

6 George Mason University, Fairfax, VA 22030, USA

7 NASA Goddard Space Flight Center, Greenbelt, MD 02138, USA

8 The Catholic University of America, Washington, DC 20064, USA

9 Department of Physics, Auburn University, Auburn, AL 36832, USA

References

[1] Gibson, S. 2015, in Solar Prominences, ed. J.-C. Vial & O. Engvold (Cham:Springer), 323, 10.1007/978-3-319-10416-4_13

[2] Howard, T. A. 2015a, ApJ, 806, 176, 10.1088/0004-637X/806/2/176

[3] Zhuang, B., Lugaz, N., Temmer, M., Gou, T., & Al-Haddad, N. 2022, ApJ, 933, 169, 10.3847/1538-4357/ac75d4

[4] Wood, B. E., Howard, R. A., & Linton, M. G. 2016, ApJ, 816, 67, 10.3847/0004-637X/816/2/67

[5] Thernisien, A. F. R., Howard, R. A., & Vourlidas, A. 2006, ApJ, 652, 763, 10.1086/508254

[6] Liu, Y., Davies, J. A., Luhmann, J. G., et al. 2010, ApJL, 710, L82, 10.1088/2041-8205/710/1/L82

[7] Lugaz, N. 2010, SoPh, 267, 411, 10.1007/s11207-010-9654-9

[8] Howard, R. A., Moses, J. D., Vourlidas, A., et al. 2008, SSRv, 136, 67, 10.1007/s11214-008-9341-4

[9] Howard, R. A., Vourlidas, A., Colaninno, R. C., et al. 2020, A&A, 642, A13, 10.1051/0004-6361/201935202

[10] Hess, P., Colaninno, R. C., Vourlidas, A., Howard, R. A., & Stenborg, G.2023, A&A, 679, A149, 10.1051/0004-6361/202346907

[11] Scott, C. J., Owens, M. J., de Koning, C. A., et al. 2019, SpWea, 17, 539, 10.1029/2018SW002093

[12] Rouillard, A. P., Davies, J. A., Forsyth, R. J., et al. 2008, GeoRL, 35, L10110, 10.1029/2008GL033767

[13] Davies, J. A., Harrison, R. A., Perry, C. H., et al. 2012, ApJ, 750, 23, 10.1088/0004-637X/750/1/23

[14] Lugaz, N., Salman, T. M., Winslow, R. M., et al. 2020, ApJ, 899, 119, 10.3847/1538-4357/aba26b

[15] Bothmer, V., & Schwenn, R. 1998, AnGeo, 16, 1, 10.1007/s00585-997-0001-x

[16] Howard, T. A. 2015b, ApJ, 806, 175, 10.1088/0004-637X/806/2/175