Astronomy and Astrophysics – Astronomy
Scientific paper
Oct 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993apj...416..647b&link_type=abstract
Astrophysical Journal v.416, p.647
Astronomy and Astrophysics
Astronomy
21
Stars: Pre-Main-Sequence, Ism: Jets And Outflows, Ultraviolet: Stars
Scientific paper
Using new long-exposure (two-shift) SWP IUE spectra of HH 2G, (HH 2H + HH 2A'), and HH 1F and archival spectra of (HH 2H + HH 2A') and of HH 1 we have obtained the following results:
1. For the first time we have determined a separate UV spectrum of the high-excitation condensation HH 2G. The spectrum shows similarity to that of HH 2R. However, the emission lines are fainter with respect to the continuum than in HH 2H. The H2 line 1505 Å (which is the strongest of the fluorescent H2 lines, that are usually typical of low-excitation objects) seems to be present.
2. The continuous energy distributions of HH 1F, of (HH 2H + HH 2A') and of HH 2G are all surprisingly similar and all show in addition to a two-photon continuum a rather strong continuous emission in the range 1400 Å ≲ λ ≲ 1600 Å which is probably due to a fluorescent H2 continuum.
3. The spatial distribution of the line emission shows separate maxima for the condensations HH 2H and HH 2A' (which are about 5" apart). The spatial distribution of the continuum emission shows, however, no maximum at HH 2A', indicating that (relative to the line emission) the continuum emission of this recently developed high-excitation condensation must be weak.
4. We have attempted to separate the partially blended Si III] 1883 and 1892 lines and to use their ratio for a determination of the electron density in the "Si III zones" of the shock waves of the HH objects. We get values about 2.5-7 times larger than those determined from the [S II] lines.
5. The time variation of the C IV 1550 and the C III] 1909 lines has been determined for HH 1 and for (HH 2H + HH 2A') during the time interval 1980-1991. In general the C IV 1550 line shows a larger variation than the C III] 1909 line. Between 1980 and 1983 there has been a rather rapid flux increase for both lines in (HH 2H + HH 2A'). We ascribe this to the rapid development of the high-excitation condensation HH 2A' during these years.
Boehm Karl-Heinz
Noriega-Crespo Alberto
Solf Josef
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