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SolarNuggets

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 Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets.  The following is a time-ordered list of the latest Nuggets added to the HelioWiki.  An [[:Category:Nugget|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).
 {{Nugget Badge
 |title = Particle Pressure and CMEs

Filament Eruptions as seen in the Sun-as-a-star H-alpha Spectrum

Hhudson — Sun, 05 Jul 2026 14:58:27 GMT

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Filament Eruptions as seen in the Sun-as-a-star H-alpha Spectrum

Hhudson — Sun, 05 Jul 2026 09:03:42 GMT

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	=== On-disk vs. Limb: the line wings ===		=== On-disk vs. Limb: the line wings ===

			The primary observational difference between on-disk and limb
			eruptions arises from the contrasting Hα appearance of filaments
			against their backgrounds. On the disk, filaments appear as dark
			absorption structures; when they erupt, cool dense material moving
			toward the observer blocks background radiation, producing blue-wing
			absorption in the integrated spectrum (see the magenta ellipse in
			Figure 1. b1). At the limb, prominences appear as bright emission
			structures against the dark background; erupting material produces
			blue-wing or red-wing emission signals (see the yellow ellipse in
			Figure 1. b2). Thus, the presence of emission in the far Hα wings
			is a strong indicator that the eruption occurred at the limb;
			otherwise, it is more likely an on-disk event.

			[[File:530f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>
			Hα imaging observations (a1a3) and corresponding Sun-as-a-star
			Hα dynamic
			spectra (b1b3) for three filament/prominence eruption events: an
			on-disk active-region eruption, a frontside limb active-region eruption,
			and a farside limb active-region eruption.
			</i>]]

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Filament Eruptions as seen in the Sun-as-a-star H-alpha Spectrum

Hhudson — Sun, 05 Jul 2026 08:49:17 GMT

Created page with "{{Infobox Nugget |name = Nugget |title = Filament Eruptions as seen in the Sun-as-a-star H-alpha Spectrum |number = 530 |first_author = Junyi ZHANG |second_author = Yijun HOU |publish_date = July 6, 2026 |next_nugget = TBD |previous_nugget = {{#ask: Category:Nugget RHESSI Nugget Index::529}} }} == Introduction == Solar filament/prominence eruptions are among the most energetic phenomena in the solar atmosphere and are major drivers of [space weather]. The..."

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{{Infobox Nugget |name = Nugget
|title = Filament Eruptions as seen in the Sun-as-a-star H-alpha Spectrum
|number = 530
|first_author = Junyi ZHANG
|second_author = Yijun HOU
|publish_date = July 6, 2026
|next_nugget = TBD
|previous_nugget = {{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::529]]}}
}}

== Introduction ==

Solar filament/prominence eruptions are among the most energetic
phenomena in the solar atmosphere and are major drivers of
[space weather].
Their geoeffectiveness depends partly on where they occur
on the Sun.
For stars beyond the Sun, however, we cannot obtain spatially resolved
images - they are observed as unresolved points.
When an eruption
happens in a localized region of a stellar atmosphere, can we infer
its approximate source location (near disk center or limb, front
side or far side, active region or quiet Sun) from subtle changes
in the star's integrated spectrum?

The answer is Yes.
We show (Ref. [1]) that filaments/prominences at
different locations display distinct radiative and dynamical
signatures during eruption, leaving identifiable imprints in the
integrated spectrum.
Using high-resolution full-disk Hα spectroscopic
data from the Chinese Hα Solar Explorer
([CHASE])
we have obtained clear spectral
fingerprints for each source-location category.

== Signatures ==

=== On-disk vs. Limb: the line wings ===