Spectral Peculiarities
Additional nomenclature, in the form of lower-case letters, can follow the spectral type to indicate peculiar features of the spectrum.
| Code | Spectral peculiarities for stars |
|---|---|
| : | Blending and/or uncertain spectral value |
| ... | Undescribed spectral peculiarities exist |
| ! | Special peculiarity |
| comp | Composite spectrum |
| e | Emission lines present |
| "Forbidden" emission lines present | |
| er | "Reversed" center of emission lines weaker than edges |
| ep | Emission lines with peculiarity |
| eq | Emission lines with P Cygni profile |
| ev | Spectral emission that exhibits variability |
| f | N III and He II emission (for element name followed by roman numeral see spectral line) |
| f* | NIV λ4058Å is stronger than the NIII λ4634Å, λ4640Å, & λ4642Å lines |
| f+ | SiIV λ4089Å & λ4116Å are emission in addition to the NIII line |
| (f) | N III emission, absence or weak absorption of He II |
| (f+) | |
| ((f)) | Displays strong HeII absorption accompanied by weak NIII emissions |
| ((f*)) | |
| h | WR stars with emission lines due to hydrogen. |
| ha | WR stars with hydrogen emissions seen on both absorption and emission. |
| He wk | Weak He lines |
| k | Spectra with interstellar absorption features |
| m | Enhanced metal features |
| n | Broad ("nebulous") absorption due to spinning |
| nn | Very broad absorption features due to spinning very fast |
| neb | A nebula's spectrum mixed in |
| p | Unspecified peculiarity, peculiar star. |
| pq | Peculiar spectrum, similar to the spectra of novae |
| q | Red & blue shifts line present |
| s | Narrowly "sharp" absorption lines |
| ss | Very narrow lines |
| sh | Shell star features |
| v | Variable spectral feature (also "var") |
| w | Weak lines (also "wl" & "wk") |
| d Del | Type A and F giants with weak calcium H and K lines, as in prototype Delta Delphini |
| d Sct | Type A and F stars with spectra similar to that of short-period variable Delta Scuti |
| Code | Abnormal CNO features |
| C | C absorption enhanced, N deficient |
| N | N absorption enhanced, C and O deficient |
| Code | If spectrum shows enhanced metal features |
| Ba | Abnormally strong Barium |
| Ca | Abnormally strong Calcium |
| Cr | Abnormally strong Chromium |
| Eu | Abnormally strong Europium |
| He | Abnormally strong Helium |
| Hg | Abnormally strong Mercury |
| Mn | Abnormally strong Manganese |
| Si | Abnormally strong Silicon |
| Sr | Abnormally strong Strontium |
| Tc | Technetium is present |
| Code | Spectral peculiarities for white dwarfs |
| : | Uncertain assigned classification |
| P | Magnetic white dwarf with detectable polarization |
| E | Emission lines present |
| H | Magnetic white dwarf without detectable polarization |
| V | Variable |
| PEC | Spectral peculiarities exist |
For example, Epsilon Ursae Majoris is listed as spectral type A0pCr, indicating general classification A0 with strong emission lines of the element chromium. There are several common classes of chemically peculiar stars, where the spectral lines of a number of elements appear abnormally strong.
Read more about this topic: Stellar Classification
Famous quotes containing the word spectral:
“How does one kill fear, I wonder? How do you shoot a spectre through the heart, slash off its spectral head, take it by its spectral throat?”
—Joseph Conrad (1857–1924)