Is the high-energy environment of K2-18b special? | Astronomy & Astrophysics (A&A)

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Table 4.

Soft X-ray flux properties for K2-18 across different observations.

Date	Observatory	Duration	Flux	logLx	L_x/L_bol	kT_peak	kT_σ	Abundance
		[ks]	[10⁻¹⁵ erg cm⁻² s⁻¹]	[erg/s]	[10⁻⁵]	[keV]	[keV]	[Solar]
2020	eROSITA	6.20	< 140.73	< 28.38		–	–	–
2023-12	Chandra	40.0	< 9.09	< 27.20		–	–	–
2024-12	XMM PN*	110.0	$5 . 89_{- 0.96}^{+ 1.04}$ $Mathematical equation: $ 5.89^{+1.04}_{-0.96} $$	27.01 ± 0.08	1.33 ± 0.23	0.51 ± 0.72	0.86 ± 0.48	0.15 ± 0.12
2024-12	XMM MOS1	110.0	$4 . 13_{- 0.98}^{+ 1.12}$ $Mathematical equation: $ 4.13^{+1.12}_{-0.98} $$	26.85 ± 0.11	0.93 ± 0.24	0.35 ± 0.15	0.28 ± 0.26	0.46 ± 0.24
2024-12	XMM MOS2	110.0	$4 . 36_{- 0.97}^{+ 0.97}$ $Mathematical equation: $ 4.36^{+0.97}_{-0.97} $$	26.88 ± 0.10	0.98 ± 0.22	0.42 ± 0.50	0.63 ± 0.42	0.18 ± 0.17

Notes. *Flux calculated for energy band 0.2–2.0 keV for XMM Newton.

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