We searched for absorption lines of highly ionized O and Ne in the energy spectra of two Low-mass X-ray binaries , 4U1820–303 in the globular cluster NGC6624 and Cyg X-2 , observed with the Chandra 
LETG , and detected O vii , O viii and Ne ix absorption lines for 4U1820–303 .
The equivalent width of the O vii { K } _ { \alpha } 
line was 1.19 ^ { +0.47 } _ { -0.30 } eV ( 90 % errors ) and the significance was 6.5 \sigma .
Absorption lines were not detected for Cyg X-2 with a 90 % upper limit on the equivalent width of 1.06 eV for O vii { K } _ { \alpha } .
The intrinsic line width was not resolved and an upper limit corresponding to a velocity dispersion of b = 420 ~ { } { km~ { } s } ^ { -1 } 
was obtained for the O vii { K } _ { \alpha } line of 4U1820–303 .
The ion column densities were estimated from the curve of growth analysis assuming several different values of b .
The absorption lines observed in 4U1820–303 are likely due to hot interstellar medium , because O will be fully photo-ionized if the absorbing column is located close to the binary system .
The velocity dispersion is restricted to b = 200 - 420 ~ { } { km~ { } s } ^ { -1 } from consistency between O vii { K } _ { \alpha } and { K } _ { \beta } lines , Ne/O abundance ratio , and H column density .
The average temperature and the O vii density are respectively estimated to be \log ( T { [ K ] } ) ~ { } = 6.2 - 6.3 and n _ { OVII } = ( 0.7 - 2.3 ) \times 10 ^ { -6 } ~ { } { cm } ^ { -3 } .
The difference of O vii column densities for the two sources may be connected to the enhancement of the soft X-ray background ( SXB ) towards the Galactic bulge region .
Using the polytrope model of hot gas to account for the SXB we corrected for the density gradient and estimated the midplane O vii density at the solar neighborhood .
The scale height of hot gas is then estimated using the AGN absorption lines .
It is suggested that a significant portion of both the AGN absorption lines and the high-latitude SXB emission lines can be explained by the hot gas in our Galaxy .