Coronae of stars with supersolar elemental abundances

Peretz, U.; Behar, E.; Drake, S. A.

doi:10.1051/0004-6361/201424769

Cited by 6 publications

(7 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The comparison we make with the photosphere of ι Hor shows no trend related to the FIP. Our results differ from those of Peretz et al (2015) Peretz et al (2015) could be due to our better statistics, which allow us to use a 3-T model to fit the spectrum, thus with a better sampling of the region where oxygen lines are formed. Our result also contradicts the conclusion made by Wood & Linsky (2010), followed by Laming (2015), in which FIP-related effects in dwarfs are correlated with spectral type, using only stars with log L X (erg s −1 )< 29.…”

Section: ι Hor As a Young Solar Analogcontrasting

confidence: 80%

“…It has been proposed that activity cycles can also act as weather seasons for biological processes in exoplanets under some circumstances (Mullan & Bais 2018). Peretz et al (2015) used the EPIC-pn spectrum to measure the coronal abundances of a few elements in ι Hor, which were then compared with the photospheric values in the literature. Our superb RGS combined spectrum allows for a more accurate measurement of the coronal abundances (Table 2, Fig.…”

Section: ι Hor As a Young Solar Analogmentioning

confidence: 99%

See 1 more Smart Citation

Multi-wavelength variability of the young solar analog ι Horologii

Sanz-Forcada

Stelzer

Coffaro

et al. 2019

A&A

View full text Add to dashboard Cite

Context. Chromospheric activity cycles are common in late-type stars; however, only a handful of coronal activity cycles have been discovered. ι Hor is the most active and youngest star with known coronal cycles. It is also a young solar analog, and we are likely facing the earliest cycles in the evolution of solar-like stars, at an age (∼ 600 Myr) when life appeared on Earth. Aims. Our aim is to confirm the ∼1.6 yr coronal cycle and characterize its stability over time. We use X-ray observations of ι Hor to study the corona of a star representing the solar past through variability, thermal structure, and coronal abundances. Methods. We analyzed multi-wavelength observations of ι Hor using XMM-Newton, TESS, and HST data. We monitored ι Hor throughout almost seven years in X-rays and in two UV bands. The summed RGS and STIS spectra were used for a detailed thermal structure model, and the determination of coronal abundances. We studied rotation and flares in the TESS light curve. Results. We find a stable coronal cycle along four complete periods, more than covered in the Sun. There is no evidence for a second longer X-ray cycle. Coronal abundances are consistent with photospheric values, discarding any effects related to the first ionization potential. From the TESS light curve we derived the first photometric measurement of the rotation period (8.2 d). No flares were detected in the TESS light curve of ι Hor. We estimate the probability of having detected zero flares with TESS to be ∼ 2%. Conclusions. We corroborate the presence of an activity cycle of ∼1.6 yr in ι Hor in X-rays, more regular than its Ca ii H&K counterpart. A decoupling of the activity between the northern and southern hemispheres of the star might explain the disagreement. The inclination of the system would result in an irregular behavior in the chromospheric indicators. The more extended coronal material would be less sensitive to this effect.

show abstract

Section: ι Hor As a Young Solar Analogcontrasting

confidence: 80%

Section: ι Hor As a Young Solar Analogmentioning

confidence: 99%

Multi-wavelength variability of the young solar analog ι Horologii

Sanz-Forcada

Stelzer

Coffaro

et al. 2019

A&A

View full text Add to dashboard Cite

show abstract

“…This discrepancy was previously noted by Maggio et al (2011) and Peretz et al (2015) based on an XMM spectrum from 2003 June 24, though those authors were looking for evidence of changes in coronal abundance behavior induced by high photospheric metallicity, rather than changes that might be induced by τ Boo A's exoplanet. One advantage of the Chandra spectrum analyzed here is that the τ Boo AB binary is resolved by Chandra, unlike XMM, meaning our τ Boo A spectrum is uncontaminated by any emission from the M2 V companion τ Boo B.…”

Section: Exoplanet Effects On Coronal Abundancesmentioning

confidence: 78%

A Chandra/LETGS Survey of Main-sequence Stars

Wood

Laming

Warren

et al. 2018

ApJ

View full text Add to dashboard Cite

We analyze the X-ray spectra of 19 main sequence stars observed by Chandra using its LETGS configuration. Emission measure (EM) distributions are computed based on emission line measurements, an analysis that also yields evaluations of coronal abundances. The use of newer atomic physics data results in significant changes compared to past published analyses. The stellar EM distributions correlate with surface X-ray flux (F X ) in a predictable way, regardless of spectral type. Thus, we provide EM distributions as a function of F X , which can be used to estimate the EM distribution of any main sequence star with a measured broadband X-ray luminosity. Comparisons are made with solar EM distributions, both full-disk distributions and spatially resolved ones from active regions (ARs), flares, and the quiet Sun. For moderately active stars, the slopes and magnitudes of the EM distributions are in excellent agreement with those of solar ARs for log T < 6.6, suggesting that such stars have surfaces completely filled with solar-like ARs. A stellar surface covered with solar X-class flares yields a reasonable approximation for the EM distributions of the most active stars. Unlike the EM distributions, coronal abundances are very spectral-type dependent, and we provide relations with surface temperature for both relative and absolute abundances. Finally, the coronal abundances of the exoplanet host star τ Boo A (F7 V) are anomalous, and we propose that this is due to the presence of the exoplanet.

show abstract

“…Wood et al (2018) extended the FIP biasspectral type relationship to include stars of earlier spectral types A and F. It is worth noting that the observed composition of stellar coronae can be more complex than having either a straightforward FIP or IFIP effect. For example, Peretz et al (2015) found that all elements were consistently depleted in the coronae of six main sequence stars of spectral type F7-K1 compared to their respective photospheres, whether compared to solar abundances or the individual stellar abundances.…”

Section: Introductionmentioning

confidence: 99%

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Baker

Driel-Gesztelyi

Brooks

et al. 2019

ApJ

View full text Add to dashboard Cite

Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of the Sun's atmosphere. High-FIP elements (>10 eV) maintain photospheric abundances in the corona, whereas low-FIP elements have enhanced abundances. Conversely, inverse FIP (IFIP) refers to the enhancement of high-FIP or depletion of low-FIP elements. We use spatially resolved spectroscopic observations, specifically the Ar XIV/Ca XIV intensity ratio, from Hinode's Extreme-ultraviolet Imaging Spectrometer to investigate the distribution and evolution of plasma composition within two confined flares in a newly emerging, highly sheared active region. During the decay phase of the first flare, patches above the flare ribbons evolve from the FIP to the IFIP effect, while the flaring loop tops show a stronger FIP effect. The patch and loop compositions then evolve toward the pre-flare basal state. We propose an explanation of how flaring in strands of highly sheared emerging magnetic fields can lead to flare-modulated IFIP plasma composition over coalescing umbrae which are crossed by flare ribbons. Subsurface reconnection between the coalescing umbrae leads to the depletion of low-FIP elements as a result of an increased wave flux from below. This material is evaporated when the flare ribbons cross the umbrae. Our results are consistent with the ponderomotive fractionation model (Laming 2015) for the creation of IFIP-biased plasma.

show abstract

Coronae of stars with supersolar elemental abundances

Cited by 6 publications

References 43 publications

Multi-wavelength variability of the young solar analog ι Horologii

Multi-wavelength variability of the young solar analog ι Horologii

A Chandra/LETGS Survey of Main-sequence Stars

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Contact Info

Product

Resources

About