4 Emission lines

As mentioned before, we have measured a total of 270 emission lines and identified 251, i.e. 93$\%$. Of these, two thirds correspond to Fe II and [Fe II]. The elements present are discussed in what follows.

• Hydrogen. Unfortunately we have only H$\delta$, H$\gamma$, H$\beta$ and H$\alpha$ of the Balmer series. H$\alpha$ is a broad line, about 6000 km$\,$s^-1 wide at the continuum level, H$\beta$ is 2400 km$\,$s^-1 wide and H$\gamma$ 1100 km$\,$s^-1 wide. The H$\delta$ line is too near to the plate limit to be able to say something meaningful. No line has an indication of a P Cyg structure.

      The Paschen series is visible up to n=28, with a clear progression from n=25 downwards. The emissions are sharp and narrow at our resolution and show no trace of underlying absorption lines.

• Helium. Lines of the ³S, ³D, ¹S and ¹D series are present, but not of the ¹P⁰ series. The lines are sharp and in single emission, except $\lambda$6678 which shows a P Cyg structure, with a separation between absorption line and emission line peaks of 170 km$\,$s^-1.
• Carbon. Ionized carbon is present with lines from M.2 and 45.
• Oxygen. Neutral oxygen is represented by lines from M.1, 4, 10, 21, 22, 23 and 34. Lines from M.1 of [O I] are also present.
• Nitrogen. Neutral nitrogen is well represented by lines from M.1, 2, 3, 8, 9 and 21.
• Magnesium. Neutral magnesium is represented by lines from M.2, 8, 11 and 22, whereas singly ionized magnesium is present with lines from M.4 and 8.
• Aluminium. Singly ionized aluminium is perhaps present with lines from M.3 and 21.
• Silicon. Ionized silicon is represented by lines from M.2, 4 and 5.
• Calcium. Ionized calcium is represented by lines from M.2 which can be seen only through the deformation of the Paschen progression.
• Titanium. Ionized titanium is represented by lines from M.41, 50 and 82. There exist also lines of [Ti II] from M.15.
• Chromium. May be present with a line from M.30.
• Manganese. Ionized manganese has lines from M.13, 19 and the line at 8783. We regard the presence of this element as dubious.
• Iron. Ionized iron is represented by many lines from M.25, 27, 28, 37, 38, 40, 41, 43, 46, 48, 49, 55, 72, 73, 74, 186, 200 and 211. Also [Fe II] is represented by many lines from M.3, 4, 6, 7, 13, 18, 19, 20, 21, 33, 34, 36 and 39.
• Nickel. Ionized nickel may be represented by two lines from M.9.

In summary we have evidence for the presence of species of 11 elements, whereas the presence of three more elements must be regarded as doubtful (Al, Cr and Mn).