Globular clusters in the galactic plane

Václav Glos

Star clusters

Main properities of globular clusters

- Age from half to nearly one Hubble time

- Tight gravitational bound of members

- Rare or none star formation

- Low metalicity

- Density profile fitable with Kings function

Credit: Marco Burali, Tiziano Capecchi, Marco Mancini

Positions of globular clusters in MW

Orbits of globular clusters in MW

Credit: Pearson Education

Absorption in visual light

Credit: Serge Brunier

Infrared solution

Milky Way in infrared

Credit: 2MASS

Finding globular clusters through disc

Credit: VSA

- Many field stars

- Non-homogenic reddening possibility

Difficulties:

Overdensity in star field

Credit: C. Moni Bidin et al.

Cluster members decontamination

Credit: C. Moni Bidin et al.

Determining cluster parameters

Cred

it: C

. Mon

i Bid

in e

t al.

Color Magnitude Diagram

- α-enhancement- metalicity- distance modulus- reddening- age

Red Giants spectra

- α-enhancement- metalicity

Globular clusters in the galactic plane

- Most in galactic bulge

- Confirmed GCs in trasition region between bulge and disc (for example GLIMPSE-C02 3,7 kpc from galactic center)

- One possible GC with distance from galaxy center 5 kpc VVV CL003

Harris W. (2003)

GLIMPSE-C02

- 3.7 kpc from galactic center

- Metal rich [Fe/H] = -0.33±0.14 in the scale of Zinn

- Compact – core radius 0.9 pc

Credit R. Kurtev et al.

VVV CL003

- 5 kpc from galactic center

- Metal rich [Fe/H] = −0.1 ± 0.2 possible open cluster?

- Deeper photometry needed

Credit: C. Moni Bidin et al.

Thank you for your attention.