  The Her-Lyr assoc., a nearby young MG, contains a few tens of ZAMS stars of
SpT F to M. The existence and the properties of the Her-Lyr assoc. are
controversial and discussed in the literature. The present work reassesses
properties and the member list of Her-Lyr assoc., based on kinematics and age.
Many objects form multiple systems or have low-mass companions and so we need
to account for multiplicity. We use our own new imaging obs. and archival data
to identify multiple systems. The colors and magnitudes of kinematic candidates
are compared to isochrones. We derive further information on the age based on
Li depletion, rotation, and coronal and chromospheric activity. A set of
canonical members is identified to infer mean properties. Membership criteria
are derived from the mean properties and used to discard non-members. The
candidates selected from the literature belong to 35 stellar systems, 42.9% of
which are multiple. Four multiple systems are confirmed in this work by common
proper motion. An orbital solution is presented for the binary system HH Leo B
and C. Indeed, a group of candidates displays signatures of youth. 7 canonical
members are identified. The distribution of EWLi of canonical Her-Lyr members
is spread widely and is similar to that of the Pleiades and the UMa group.
Gyrochronology gives an age of 257+-46 Myr which is in between the ages of the
Pleiades and the Ursa Major group. The measures of chromospheric and coronal
activity support the young age. Four membership criteria are presented based on
kinematics, EWLi, chromospheric activity, and gyro. age. In total, 11 stars are
identified as certain members including co-moving objects plus additional 23
possible members while 14 candidates are doubtful or can be rejected. A
comparison to the mass function, however, indicates the presence of a large
number of additional unidentified low-mass members.
