SIMBAD references

We present new spectroscopic observations between 3100 and 5100 Å and 3500 and 7500 Å of the stars Hen 3-461, Hen 3-653, Hen 2-156, V704 Cen, Mac 1-17, V3804 Sgr, and V2905 Sgr. Except for V3804 Sgr, which presents a flat spectrum in the optical range, and V704 Cen, all the objects have late-type continuum spectra, and some have H I, He I, He II λ4686, and [O III] λ5007 emission lines. All the objects have been previously classified as suspected symbiotic stars. We find that five of them (Hen 3-461, Hen 2-156, Mac 1-17, V3804 Sgr, and V2905 Sgr) are symbiotic stars. The nature of two objects, Hen 3-653 and V704 Cen, is still uncertain despite their symbiotic behavior. We also present a discussion of the nature of each object.