Table 3: Spectral properties of BDs obtained from spectral fitting. To fit the spectra (Fig. 4), we used a WABS absorption model (Morrison & McCammon 1983) combined with one or two MEKAL optically thin thermal plasma model (Mewe et al. 1995) with 0.3 times the solar elemental abundances. MEKAL plasma models were computed rather than interpolated from a pre-calculated table. We used $\chi ^2$ statistics with standard weighting. Column (4) gives the net source counts collected by the instrument given in Col. (3). Confidence ranges at the 68% level ( $\Delta \chi ^2=1$ ; corresponding to $\sigma =1$ for Gaussian statistics) are given in parentheses. The value of reduced $\chi ^2$ and $\nu$ , the degrees of freedom, are indicated in Col. (10). The emission measures in Cols. (8) and (9) and the X-ray luminosity in the 0.5-8 keV energy range corrected for absorption in Col. (11) were computed assuming a distance of 140 pc for the TMC. The X-ray fractional luminosity, $\eta=\log (L_{\rm X}/L_*)$ , is given in the last column. For CFHT-BD-Tau 1, the second line gives an estimate of the quiescent X-ray luminosity derived for the light curve fit (see Sect. 3).
BD name Instr. N $N_{\rm H}$ kT₁ kT₂ EM₁ EM₂ $\chi^2_\nu$ ( $\nu$ ) $L_{\rm X}$ $\eta$

# 10²¹ cm^-2 keV 10⁵¹ cm^-3 10²⁸ erg s^-1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)

1 2MASS J0422 pn 102 1.7 (0.9-2.8) 0.7 (0.6-0.8) 2 0.83 (07) 02.0 -3.5

3a MHO 4 EPIC 571 1.2 (0.7-1.7) 0.4 (0.3-0.5) 1.1 (1.0-1.2) 5 6 0.56 (26) 08.3 -3.3

3b MHO 4 ACIS-I 271 0 (0-0.2) 0.5 (0.4-0.6) 1.1 (1.1-1.3) 4 6 0.85 (18) 08.0 -3.4

4a CFHT-Tau 5 EPIC 314 4.9 (3.7-7.7) 1.5 (1.2-1.9) 14 0.82 (13) 11.8 -3.4

5 CFHT-BD-Tau 1 EPIC 206 6.0 (3.9-10.2) 1.7 (1.1-2.6) 17 0.59 (06) 14.3 -2.7

07.7 -2.9

8 CFHT-BD-Tau 4 ACIS-I 33 8.6 (5.6-13.9) 0.5 (0.2-0.9) 27 0.74 (3) 24.3 -3.0

**Table 3:** Spectral properties of BDs obtained from spectral fitting. To fit the spectra (Fig. 4), we used a `WABS` absorption model (Morrison & McCammon 1983) combined with one or two `MEKAL` optically thin thermal plasma model (Mewe et al. 1995) with 0.3 times the solar elemental abundances. `MEKAL` plasma models were computed rather than interpolated from a pre-calculated table. We used $\chi ^2$ statistics with standard weighting. Column (4) gives the net source counts collected by the instrument given in Col. (3). Confidence ranges at the 68% level ( $\Delta \chi ^2=1$ ; corresponding to $\sigma =1$ for Gaussian statistics) are given in parentheses. The value of reduced $\chi ^2$ and $\nu$ , the degrees of freedom, are indicated in Col. (10). The emission measures in Cols. (8) and (9) and the X-ray luminosity in the 0.5-8 keV energy range corrected for absorption in Col. (11) were computed assuming a distance of 140 pc for the TMC. The X-ray fractional luminosity, $\eta=\log (L_{\rm X}/L_*)$ , is given in the last column. For CFHT-BD-Tau 1, the second line gives an estimate of the quiescent X-ray luminosity derived for the light curve fit (see Sect. 3).
	BD name	Instr.	N	$N_{\rm H}$	kT₁	kT₂	EM₁	EM₂	$\chi^2_\nu$ ( $\nu$ )	$L_{\rm X}$	$\eta$
#				10²¹ cm^-2	keV	10⁵¹ cm^-3		10²⁸ erg s^-1
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)
1	2MASS J0422	pn	102	1.7 (0.9-2.8)	0.7 (0.6-0.8)		2		0.83 (07)	02.0	-3.5
3a	MHO 4	EPIC	571	1.2 (0.7-1.7)	0.4 (0.3-0.5)	1.1 (1.0-1.2)	5	6	0.56 (26)	08.3	-3.3
3b	MHO 4	ACIS-I	271	0 (0-0.2)	0.5 (0.4-0.6)	1.1 (1.1-1.3)	4	6	0.85 (18)	08.0	-3.4
4a	CFHT-Tau 5	EPIC	314	4.9 (3.7-7.7)	1.5 (1.2-1.9)		14		0.82 (13)	11.8	-3.4
5	CFHT-BD-Tau 1	EPIC	206	6.0 (3.9-10.2)	1.7 (1.1-2.6)		17		0.59 (06)	14.3	-2.7
										07.7	-2.9
8	CFHT-BD-Tau 4	ACIS-I	33	8.6 (5.6-13.9)	0.5 (0.2-0.9)		27		0.74 (3)	24.3	-3.0

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