The Coronal Abundance Anomalies of M Dwarfs

Wood, Brian E.; Laming, J. M.; Karovska, M.

doi:10.1088/0004-637x/753/1/76

Cited by 37 publications

(63 citation statements)

References 39 publications

(56 reference statements)

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“…We initially set elemental abundances to Solar values (Asplund et al 2009), but we found that the spectral fit was improved significantly around 1 keV by allowing the Fe and Mg abundances to drop below Solar values (values of 0.03-0.19 Solar). This is consistent with the "inverse FIP effect" seen in very active stars and M dwarfs (where FIP refers to the first ionisation potential of the element; Wood & Linsky 2010;Wood et al 2012;Laming 2015).…”

Section: X-ray Emissionsupporting

confidence: 85%

Detection of a giant flare displaying quasi-periodic pulsations from a pre-main-sequence M star by the Next Generation Transit Survey

Jackman

Wheatley

Pugh

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present the detection of an energetic flare on the pre-main sequence M3 star NGTS J121939.5-355557, which we estimate as only 2 Myr old. The flare had an energy of 3.2 ± 0.4 0.3 ×10 36 erg and a fractional amplitude of 7.2 ± 0.8, making it one of the most energetic flares seen on an M star. The star is also X-ray active, in the saturated regime with logL X /L Bol = −3.1. In the flare peak we have identified multi-mode quasi-periodic pulsations formed of two statistically significant periods of approximately 320 and 660 seconds. This flare is one of the largest amplitude events to exhibit such pulsations. The shorter period mode is observed to start after a short-lived spike in flux lasting around 30 seconds, which would not have been resolved in Kepler or TESS short cadence modes. Our data shows how the high cadence of NGTS can be used to apply solar techniques to stellar flares and identify potential causes of the observed oscillations. We also discuss the implications of this flare for the habitability of planets around M star hosts and how NGTS can aid in our understanding of this.

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Section: X-ray Emissionsupporting

confidence: 85%

Detection of a giant flare displaying quasi-periodic pulsations from a pre-main-sequence M star by the Next Generation Transit Survey

Jackman

Wheatley

Pugh

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Objects marked with an X were already included in Wood & Laming (2013). Solid lines bound all of the stars in Wood et al (2012) except for one.…”

Section: Fip Effectmentioning

confidence: 99%

Coronae of stars with supersolar elemental abundances

Peretz

Behar

Drake

2015

A&A

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Coronal elemental abundances are known to deviate from the photospheric values of their parent star, with the degree of deviation depending on the first ionization potential (FIP). This study focuses on the coronal composition of stars with supersolar photospheric abundances. We present the coronal abundances of six such stars: 11 LMi, ι Hor, HR 7291, τ Boo, and α Cen A and B. These stars all have high-statistics X-ray spectra, three of which are presented for the first time. The abundances we measured were obtained using the line-resolved spectra of the Reflection Grating Spectrometer (RGS) in conjunction with the higher throughput EPIC-pn camera spectra onboard the XMM-Newton observatory. A collisionally ionized plasma model with two or three temperature components is found to represent the spectra well. All elements are found to be consistently depleted in the coronae compared to their respective photospheres. For 11 LMi and τ Boo no FIP effect is present, while ι Hor, HR 7291, and α Cen A and B show a clear FIP trend. These conclusions hold whether the comparison is made with solar abundances or the individual stellar abundances. Unlike the solar corona, where low-FIP elements are enriched, in these stars the FIP effect is consistently due to a depletion of high-FIP elements with respect to actual photospheric abundances. A comparison with solar (instead of stellar) abundances yields the same fractionation trend as on the Sun. In both cases, a similar FIP bias is inferred, but different fractionation mechanisms need to be invoked.

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“…The coronae of solar-like stars exhibit a varying degree of the solar-like FIP effect in their X-ray spectra whereas more active cool dwarf stars show an inverse FIP (IFIP) effect. In surveys of M dwarf stars and active binaries, low-FIP elements are under-abundant relative to high-FIP elements e.g., O, Ne, Ar (e.g., Brinkman et al 2001;Telleschi et al 2005;Robrade & Schmitt 2005;Argiroffi et al 2005;Robrade & Schmitt 2006;Wood & Linsky 2006;Liefke et al 2008;Wood et al 2012). Wood & Linsky (2010) firmly established the dependence of the (I)FIP effects on F to K spectral type stars with X-ray luminosity <10 29 ergs s −1 .…”

Section: Introductionmentioning

confidence: 98%

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Baker

Driel-Gesztelyi

Brooks

et al. 2019

ApJ

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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.

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The Coronal Abundance Anomalies of M Dwarfs

Cited by 37 publications

References 39 publications

Detection of a giant flare displaying quasi-periodic pulsations from a pre-main-sequence M star by the Next Generation Transit Survey

Detection of a giant flare displaying quasi-periodic pulsations from a pre-main-sequence M star by the Next Generation Transit Survey

Coronae of stars with supersolar elemental abundances

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

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