Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance

Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

doi:10.1051/swsc/2016028

Cited by 6 publications

(5 citation statements)

References 72 publications

(82 reference statements)

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“…The simultaneous long-term measurements of the total and spectral solar irradiances (TSI and SSI, respectively) by SORCE (SOlar Radiation and Climate Experiment) show that the Lyman-α variability patterns deviate from the TSI changes on Carrington rotational timescales, especially during the highactivity epochs when the line frequently anticorrelates with TSI. The Hα line-flux, though, mostly follows TSI (Lee et al 2016).…”

Section: Introductionmentioning

confidence: 95%

Solar activity and responses observed in Balmer lines

Марченко

Criscuoli

DeLand

et al. 2021

A&A

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Context. Many stars show Sun-like magnetic activity cycles, which are frequently observed by tracking changes in the chromospherically sensitive CaII H&K doublet. However, relationships between the line profile changes related to the magnetic activity seen in strong spectral transitions in other portions of a stellar spectrum are yet to be understood. Aims. We follow variability patterns in various solar lines in order to relate them to the emergence, passage, and decay of active solar regions. Methods. The line activity indices (core-to-wing ratio) for the upper Balmer lines – Hβ, Hγ, and Hδ – are constructed from the near-daily solar measurements acquired by the Ozone Monitoring Instrument and the TROPOspheric Monitoring Instrument. Results. On solar rotation timescales, the upper Balmer line activity indices closely follow variations in the total solar irradiance, r ∼ −(0.6 − 0.7), and thus frequently deviate from the behavior of the line activity indices that track chromospheric activity levels (e.g., the CH 430 nm band used in this study), specifically during passages of big sunspot groups.

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Section: Introductionmentioning

confidence: 95%

Solar activity and responses observed in Balmer lines

Марченко

Criscuoli

DeLand

et al. 2021

A&A

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“…While the radiation, dynamics, and chemistry in the UMLT are largely driven by solar radiation, solar cycle‐driven UV irradiance changes are expected to significantly modulate ozone abundances within the secondary ozone maximum layer. Substantial variation in solar UV irradiance, larger than several percent over the 11‐year solar cycle (Lee et al, ), directly impacts ozone chemistry, because the major single source of secondary maximum ozone production is photochemistry of oxygen species from the Chapman cycle (Chapman, ). This ozone production photochemistry involves reaction between atomic oxygen (O) and molecular oxygen (O 2 ),

O_{2} + italichv \to O + O,

O + O_{2} + M \to O_{3} + M,

where M indicates the total density of the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Solar Cycle Modulation of Nighttime Ozone Near the Mesopause as Observed by MLS

Lee

2020

Earth and Space Science

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Eleven-year solar cycle variations of nighttime ozone near the secondary ozone maximum layer in the mesosphere are analyzed with Aura Microwave Limb Sounder (MLS) observations since 2004, fully covering solar cycle 24. Produced primarily from the recombination of molecular oxygen (O 2 ) with atomic oxygen (O) transported from the lower thermosphere, the mesospheric nighttime ozone concentration is proportional to atomic oxygen density [O], which itself is modulated by ultraviolet (UV) solar cycle variations. MLS nighttime ozone data and UV data at 240 nm from Solar Radiation and Climate Experiment (SORCE) Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) show a positive correlation over the solar cycle. Nighttime O 3 and nighttime carbon monoxide (CO) distributions are highly correlated with each other with similar seasonal and solar cycle variations, because both [O 3 ] and [CO] depend strongly on UV photolysis and are modulated by Eddy diffusion in this region. Nighttime ozone correlates strongly with temperature, with a generally positive correlation, except at high latitudes during boreal winter.

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“…The amplitude of rotational modulation for the simulation of the Sun-like star (M(A = 1)) at 4 000 Å is ∼ 0.06%. This single example of rotational modulation lies only somewhat below the value of ≈ 0.1 − 0.2% characteristic of the active Sun (Fröhlich 2016;Lee et al 2016).…”

Section: Rotational Modulationmentioning

confidence: 72%

Testing the Solar Activity Paradigm in the Context of Exoplanet Transits

Schrijver

2020

ApJ

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Transits of exoplanets across cool stars contain blended information about structures on the stellar surface and about the planetary body and atmosphere. To advance understanding of how this information is entangled, a surface-flux transport code, based on observed properties of the Sun's magnetic field, is used to simulate the appearance of hypothetical stellar photospheres from the visible near 4000Å to the near-IR at 1.6 µm, by mapping intensities characteristic of faculae and spots onto stellar disks. Stellar appearances are computed for a Sun-like star of solar activity up to a star with mean magnetic flux density ∼ 30× higher. Simulated transit signals for a Jupiter-class planet are compared with observations. This (1) indicates that the solar paradigm is consistent with transit observations for stars throughout the activity range explored, provided that infrequent large active regions with fluxes up to ∼ 3 × 10 23 Mx are included in the emergence spectrum, (2) quantitatively confirms that for such a model, faculae brighten relatively inactive stars while starspots dim more-active stars, and suggests (3) that large starspots inferred from transits of active stars are consistent with clusters of more compact spots seen in the model runs, (4) that wavelength-dependent transit-depth effects caused by stellar magnetic activity for the range of activity and the planetary diameter studied here can introduce apparent changes in the inferred exoplanetary radii across wavelengths from a few hundred to a few thousand kilometers, increasing with activity, and (5) that activity-modulated distortions of broadband stellar radiance across the visible to near-IR spectrum can reach several percent.

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Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance

Cited by 6 publications

References 72 publications

Solar activity and responses observed in Balmer lines

Solar activity and responses observed in Balmer lines

Solar Cycle Modulation of Nighttime Ozone Near the Mesopause as Observed by MLS

Testing the Solar Activity Paradigm in the Context of Exoplanet Transits

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