classification (Slettebak 1954), whereas the MK types classified by Osawa for faint
stars markedly deviated toward the late type, as shown in Fig. 3.17.
3.7.2.4 Observations at OAO
Osawa and his group mainly used a 91 cm reflector for photoelectric observations.
He observed several types of variable objects, as shown in Table 3.9, where the
characteristics for some stellar types are briefly given as follows:
Hydrogen-deficient stars show little or no hydrogen in their atmosphere and
generally belong to early-type stars in a wide luminosity class.
A-type peculiar stars belong to the type of chemically peculiar stars, including
metallic-line stars (Am stars) and stars of strong magnetic field.
Fig. 3.17 Comparison of HD spectral types with MK types for A-type stars. Left panel: classification by Slettebak for bright stars (m < 5.5); right panel: classification by Osawa for faint stars
(m > 6.5) (Slettebak 1954; Osawa 1963, 1966)
Table 3.9 List of stars observed by Osawa at OAO
Stellar type
Star name
Observation year
Hydrogen-deficient star
HD 30353
1963
A-type peculiar star
HD 221568
1963
Flare star
UV Ceti
1968–1973
YZ CMi
1968–1973
EV Lac
1969–1971
AD Leo
1970–1974
Novae
N Cygi
1975
N Sagittarius
1975
Nova-like star
In Ophiuckus
1976
Comets
Kohoutek
1973
Heck-Same
1973
Gehrels 2
1973
Kobayashi et al
1975
Mori-Sato et al.
1975
Sato
1975
3.7 Osawa Kiyoteru and Stellar Physics
71
stars markedly deviated toward the late type, as shown in Fig. 3.17.
3.7.2.4 Observations at OAO
Osawa and his group mainly used a 91 cm reflector for photoelectric observations.
He observed several types of variable objects, as shown in Table 3.9, where the
characteristics for some stellar types are briefly given as follows:
Hydrogen-deficient stars show little or no hydrogen in their atmosphere and
generally belong to early-type stars in a wide luminosity class.
A-type peculiar stars belong to the type of chemically peculiar stars, including
metallic-line stars (Am stars) and stars of strong magnetic field.
Fig. 3.17 Comparison of HD spectral types with MK types for A-type stars. Left panel: classification by Slettebak for bright stars (m < 5.5); right panel: classification by Osawa for faint stars
(m > 6.5) (Slettebak 1954; Osawa 1963, 1966)
Table 3.9 List of stars observed by Osawa at OAO
Stellar type
Star name
Observation year
Hydrogen-deficient star
HD 30353
1963
A-type peculiar star
HD 221568
1963
Flare star
UV Ceti
1968–1973
YZ CMi
1968–1973
EV Lac
1969–1971
AD Leo
1970–1974
Novae
N Cygi
1975
N Sagittarius
1975
Nova-like star
In Ophiuckus
1976
Comets
Kohoutek
1973
Heck-Same
1973
Gehrels 2
1973
Kobayashi et al
1975
Mori-Sato et al.
1975
Sato
1975
3.7 Osawa Kiyoteru and Stellar Physics
71