Definite [Cr IV] nebular lines 6748, 6896, 6915 seen in Orion and 30 Dor

[will-henney]

These are weakish lines in Orion. The one I found first is 6748, but now I see 6896 and 6915 too, with 6915 being the strongest. It is odd that I never saw them before. We do not see 6734 because of blend with [S II].

Atomic Line List version: 3.00b4   Constructed: 2021-07-21 14:47 GMT
Wavelength range: 0 - inf   Unit: Angstrom   Type: Air
Radial velocity: 0 km/s
Element/Spectrum: Cr IV

-LAB-WAVL-ANG-AIR-|-DLAM--|--SPC--|TT|-CONF--|TERM-|-J_i-J_k-|--A_ki---|-dA_ki-|-TPF-|--LVL-EN--CM-1---|-REF---|
   6592.31         2.5e-01 [Cr IV] E2 3d3-3d3 4F-2G 5/2 - 9/2                         237.40 - 15402.40 090
   6641.10         2.5e-01 [Cr IV] E2 3d3-3d3 4F-2G 3/2 - 7/2                           0.00 - 15053.60 090
   6733.96         2.6e-01 [Cr IV] M1 3d3-3d3 4F-2G 7/2 - 9/2 3.600e-02 3.6e-02   ASD 556.40 - 15402.40 090
   6747.51         2.6e-01 [Cr IV] M1 3d3-3d3 4F-2G 5/2 - 7/2 3.200e-02 3.2e-02   ASD 237.40 - 15053.60 090
   6895.98         2.7e-01 [Cr IV] M1 3d3-3d3 4F-2G 7/2 - 7/2 3.500e-02 3.5e-02   ASD 556.40 - 15053.60 090
   6915.20         2.7e-01 [Cr IV] M1 3d3-3d3 4F-2G 9/2 - 9/2 9.300e-02 9.3e-02   ASD 945.50 - 15402.40 090
   7086.17         2.8e-01 [Cr IV] M1 3d3-3d3 4F-2G 9/2 - 7/2 2.300e-03 2.3e-03   ASD 945.50 - 15053.60 090

[will-henney]

Here are images of Orion

[Cr IV] 6915

Peak wavelength of line

And one pixel to the blue, showing HH 202 better

[will-henney]

And here are ones of 30 Dor field A. I do not seen any obvious jets in this. It is mainly just nebular emission. We would have to look at the N fields to maybe see jets

[will-henney]

We do not seem to see these at all in NGC 346. But the spectrum around there seems affected badly by the sky