The coolest thermally emitting NSs with available B + RX J1856.5-3754
[1] Burwitz et al, 2001; [2] Drake et al, 2002; [3]
Paerels et al, 2001; [4]Zane et al, 2002; [5} Hambaryan et al,
2002; [6] Pavlov et al, 2001; [7] Taylor et al, 1993; [8] Halpern
& Wang, 1997; [9] Bignami & Caraveo, 1996; [10]
Marshall & Schulz 2002; [11] Greivendilger et al, 1996.
Most
Isolated Neutron Stars have T well in excess of THcrit :
Þ if
surface layers are H-dominated an
atmosphere is unavoidable.
But:
if some objects have not accreted much gas:
Þ we may detect thermal
emission directly from the iron surface layers
Þ
depending on B the outer layers of RX J1856.5-3754 might be in form of condensed matter
!
SPECTRUM?
Critical T for H and Fe. Condensation is possible in the shaded region for Fe and in the cross-hatched region for H. Filled circles are the NSs listed in the table. The horizontal line is the color temperature of RX J1856.5-3754