4 Her - Bibliographie et évolutions

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4 Her, HD 142926, HR 5938

Information :

In emission since 1996, we are waiting for an absorption return in 2011-2012.

What we know

Spectroscopic binary P=46.023d (Pédoussant et al., 1977)

P=46.194 (Heard et al., 1975)

Activity 1921 : Ha absorption

1939 : Ha emission

1940 : Ha emission , Hb absorption (Heard, A&A, 42,47)

1949 : weaker emission

1953-63 : Ha absorption (Hubert, A&A, 11,100)

1964 : Ha strong emission

1967-68 : Ha two peaks emission (Cowler et al., PASP, 80, 685)

1969-71 : Ha emission (Harmanec et al., BAICz, 27, 47)

1982:Ha emission (Andrillat et al., A&AS,48,93)

1989-91 : Ha no emission detected (Koubsky et al., A&A, 277, 521 and A&A, 328,551)

1996-2010 : Ha emission in BESS

Hubert suggests a 28 years period (13 for emission, 15 for absorption) Non emission phase coincide with maximum brigthness and blueshift of the star

Conclusion :

P, if exists, is very uncertain.

In emission since 1996, we are waiting for an absorption return in 2011-2012.