The masses of open star clusters and their tidal tails and the stellar initial mass function

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F24%3A10492222" target="_blank" >RIV/00216208:11320/24:10492222 - isvavai.cz</a>

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=kw4uxLnMIF" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=kw4uxLnMIF</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202347839" target="_blank" >10.1051/0004-6361/202347839</a>

Result language

angličtina

Original language name

The masses of open star clusters and their tidal tails and the stellar initial mass function

Original language description

Context. Unresolved binaries have a strong influence on the observed parameters of stellar clusters (SCs). Aims. We quantify this influence and compute the resulting mass underestimates and stellar mass function (MF). Methods. N-body simulations of realistic SCs were used to investigate the evolution of the binary population in a SC and its tidal tails. Together with an empirically gauged stellar mass-luminosity relation, the results were then used to determine how the presence of binaries changes the photometric mass and MF of the SC and its tails as deduced from observations. Results. Tail 1 (T1), which is the tidal tail caused by gas expulsion, contains a larger fraction of binaries than both the SC and Tail 2 (T2), which forms after gas expulsion. Additionally, T1 has a larger velocity dispersion. Using the luminosity of an unresolved binary, an observer would underestimate its mass. This bias sensitively depends on the companion masses due to the structure of the stellar mass-luminosity relation. Combining the effect of all binaries in the simulation, the total photometric mass of the SC is underestimated by 15%. Dark objects (black holes and neutron stars) increase the difference between the real and observed mass of the SC further. For both the SC and the tails, the observed power-law index of the MF between a stellar mass of 0.3 and 0.7 M-circle dot is smaller by up to 0.2 than the real one, the real initial mass function (IMF) being steeper by this amount. This difference is larger for stars with a larger velocity dispersion or binary fraction. Conclusions. Since the stars formed in SCs are the progenitors of the Galactic field stars, this work suggests that the binary fractions of different populations of stars in the Galactic disc will differ as a function of the velocity dispersion. However, the direction of this correlation is currently unclear, and a complete population synthesis will be needed to investigate this effect. Variations in the binary fractions of different clusters can lead to perceived variations of the deduced stellar MFs.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/GA20-21855S" target="_blank" >GA20-21855S: The dynamics of dense star clusters with primordial binaries and massive black holes</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy &amp; Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

691

Issue of the periodical within the volume

listopad

Country of publishing house

FR - FRANCE

Number of pages

15

Pages from-to

A143

UT code for WoS article

001352040700002

EID of the result in the Scopus database

2-s2.0-85208941630