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Additional
Herbig Ae/Be star
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Herbig Ae/Be star
A
Herbig Ae/Be star
(
HABe
) is a
pre-main-sequence star
– a young (<10Myr) star of
spectral types
A or B. These stars are still embedded in gas-dust envelopes and are sometimes accompanied by
circumstellar disks
.
Hydrogen
and
calcium
emission lines are observed in their spectra. They are 2-8
Solar mass
objects, still existing in the
star formation
(gravitational contraction) stage and approaching the
main sequence
(i.e. they are not
burning hydrogen
in their center). In the
Hertzsprung–Russell diagram
these stars are located to the right of the
main sequence
. They are named after the American astronomer
George Herbig
, who first distinguished them from other
stars
in 1960. The original
Herbig
criteria were:
Spectral type
earlier than F0 (in order to exclude
T Tauri stars
),
Balmer emission lines
in the stellar spectrum (in order to be similar to
T Tauri stars
),
Projected location within the boundaries of a dark
interstellar cloud
(in order to select really young stars near their birthplaces),
Illumination of a nearby bright
reflection nebula
(in order to guarantee physical link with
star formation
region).
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