With the XMM-Newton and Chandra observatories , we detected two extremely embedded X-ray sources in the R Corona Australis ( R CrA ) star forming core , near IRS 7 .
These sources , designated as X _ { { E } } and X _ { W } , have X-ray absorption columns of \sim 3 \times 10 ^ { 23 } cm ^ { -2 } equivalent to A _ { V } \sim 180 ^ { m } .
They are associated with the VLA centimeter radio sources 10E and 10W , respectively .
X _ { W } is the counterpart of the near-infrared source IRS 7 , whereas X _ { { E } } has no K -band counterpart above 19.4 ^ { m } .
This indicates that X _ { { E } } is younger than typical Class I protostars , probably a Class 0 protostar or in an intermediate phase between Class 0 and Class I .
The X-ray luminosity of X _ { { E } } varied between 29 < \log L _ { X } < 31.2 ergs s ^ { -1 } on timescales of 3–30 months .
X _ { { E } } also showed a monotonic increase in X-ray brightness by a factor of two in 30 ksec during an XMM-Newton observation .
The XMM-Newton spectra indicate emission from a hot plasma with kT \sim 3–4 keV and also show fluorescent emission from cold iron .
Though the X-ray spectrum from X _ { { E } } is similar to flare spectra from Class I protostars in luminosity and temperature , the light curve does not resemble the lightcurves of magnetically generated X-ray flares because the variability timescale of X _ { { E } } is too long and because variations in X-ray count rate were not accompanied by variations in spectral hardness .
The short-term variation of X _ { { E } } may be caused by the partial blocking of the X-ray plasma , while the month-long flux enhancement may be driven by mass accretion .