- The 13
top stellar spectra
show regular spectral types
from the
OBAFGKM stellar classification:
temperature decreases top to bottom.
The bottom 3
stellar spectra
are special types.
- The spectral types are labeled on
the left side of the image.
- The right side of the image
gives the
star catalog name
for stars drawn from the
Henry Draper Catalogue (1918--1949),
Smithsonian
Astrophysical Observatory Star Catalog (1966),
Bonner Durchmusterung (BD),
and
Bright Star Catalogue
(Yale Bright Star Catalogue, YBS (1930--1991).
Note usually only
bright stars
have
star proper names: i.e.,
the named stars.
Also note that stars often have multiple names:
e.g.,
star proper names,
Bayer designations,
and multiple
star catalog names.
- The
hydrogen Balmer lines
(i.e., the visible band atomic hydrogen lines)
are strongest in absorption for A0--A5
A stars
which have
photospheric temperatures
of order 9000 K
(FK-424).
- In the image, the blue-green Hβ (486.132 nm) and
violet-blue Hγ (434.046 nm)
absorption lines are quite
apparent on and about the A1 spectrum
(FK-423).
- The red Hα (656.280 nm) is somewhat darkened out
for the A1 spectrum, but can still be made out
(FK-423).
- The sodium (Na) I double D lines (588.995, 589.592 nm)
in the yellow are quite noticeable for the M0 and M5
M stars
(FK-423).
The Na I double D lines
are the strongest lines of neutral
sodium.
They give low-pressure sodium-vapor lamps
their nearly
monochromatic
yellow light.
- As we know from Wien's law,
the maximum of a
blackbody spectrum
should shift to the
red as temperature decreases.
This is apparently shown in this image since bright zone forms
a broad diagonal from upper right to lower left.
But since colors in images
can be easily manipulated, it is
hard to know if we are really seeing this effect.
Credit/Permission: