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In Figures 2 and 3 we show the 6m telescope spectra of blue compact galaxies
HS 1013+3809 and HS 1442+4250, in which
typical high excitation HII-region narrow emission lines are seen.
They are H
4861, [OIII]
4959,5007
and
4363,
several lines of HeI, [NeIII] and [ArIV]
for both spectra and
H
6562, [NII]
6548,6584 and [SII]
6716,6731 Å for red part of HS 1442+4250.
We postpone more detailed analysis of these spectra in conjunction with
other observational data to forthcoming paper. In here we use only
the observed intensities of important hydrogen and oxygen lines
to derive the oxygen abundance in both BCGs. They are presented in
Table 1, as well as those corrected for extinction and underlying Balmer
absorptions (Izotov et al. 1997a).
All intensities of lines are given relative to H
,
along with
the equivalent width of H
line EW(H
),
the observed H
flux F(H
),
the extinction coefficient C(H
)
and observed redshift.
To derive Te in regions of OIII and OII and oxygen
abundance, we followed the algorithms also described
in Izotov et al. (1997a).
To estimate electron density Ne(SII) in HS 1442+4250 the intensity ratio
of [SII] lines
6716 and 6731 Å was used as usual.
Since the observed ratio
the value Ne= 10 cm-3 was used (Aller 1984) for this object.
For HS 1013+3809 the typical for BCGs value Ne= 10 cm-3 was adopted
as well.
The BCG's absolute blue magnitudes presented in Table 1 are
calculated with the
KUG and UGC catalogs' apparent B-magnitudes and measured heliocentric
velocities. The Galaxy extinction correction is not applied since it is
very small in comparison with apparent magnitude uncertainties.
For so nearby galaxies to get higher precision estimate of their distance
the Virgo flow correction and the motion relative to Local group is necessary
to take into account (e.g. Kraan-Korteweg, 1986).
This correction
= 354 km s-1 was calculated for HS 1013+3809
and
= 202 km s-1 for HS 1442+4250.
The Hubble constant was adopted as 75 km s-1 Mpc-1.
Well known Wolf-Rayet features are seen in the spectrum of HS 1442+4250, what makes it interesting for study evolution of massive stars in this galaxy on the time-scale of few Myr (Izotov et al. 1997b).
The morphology of these two galaxies is very different. While HS 1013+3809 looks very symmetric and very compact, with intense star formation burst taking place in its very center, HS 1442+4250 is well elongated, resembling edge-on disk. Strong star formation burst in SW knot is well outside the center of symmetry of this elongated configuration. Another fainter knot from the opposite side of this "disk" is well seen on DSS image, but its spectrum is not yet obtained. This different morphology and relative positions of star formation regions indicate possible different mechanisms of bursting star formation in gas-rich low-mass galaxies.