Star Cluster Disruption in the Starburst Galaxy Messier 82

Abstract

Using high-resolution, multiple-passband Hubble Space Telescope images spanning the entire optical/near-infrared wavelength range, we obtained a statistically complete sample, U -band selected sample of 846 extended star clusters across the disk of the nearby starburst galaxy M82. Based on careful analysis of their spectral energy distributions, we determined their galaxy-wide age and mass distributions. The M82 clusters exhibit three clear peaks in their age distribution, thus defining a relatively young, log(t yr −1 ) ≤ 7.5, an intermediate-age, log(t yr −1 ) ∈ [7.5, 8.5], and an old sample, log(t yr −1 ) ≥ 8.5. Comparison of the completeness-corrected mass distributions offers a firm handle on the galaxy's star cluster disruption history. The most massive star clusters in the young and old samples are (almost) all concentrated in the most densely populated central region, while the intermediate-age sample's most massive clusters are more spatially dispersed, which may reflect the distribution of the highest-density gas throughout the galaxy's evolutionary history, combined with the solid-body nature of the galaxy's central region.

Star Cluster Formation and Evolution in M101: An Investigation with the Legacy Extragalactic UV Survey

“…Importantly, the distribution slopes measured for the C region also remain steeper than the NW region regardless of the mass range considered. These conclusions are what we would expect for environmentally dependent disruption for the cluster populations in M101, and are similar to the results found when analyzing the young and old cluster populations in M82 (Li et al 2015). In Table 2, we give the number of clusters used to fit the distributions shown in Figure 8 for all three regions in M101.…”

A comparative study of analytical representations of potential energy curves for CO in its ground electronic state

“…The smallest Z value implies the most accurate potential energy function. The RKR data used in the comparison for the diatomic system CO [5] was obtained from the literature.…”

“…In addition to the Z test, to prove the accuracy of the potential energy functions, in Table 3 the vibrational levels of the CO($$$ {X}^1{\Sigma}^{+} $$$) electronic state are also presented for all potentials and compared with experimental data [5]. For comparison, an accurate ab initio CO potential proposed in 2011 [23] has been included.…”

Young star clusters in circumnuclear starburst rings

“…Following the same steps as in our previously established image reduction and analysis protocol (e.g., de Grijs et al 2013a;Li et al 2015; and references therein), we ran our custom-written idl 3 source-finding routines on two 'middlewavelength' images for each galaxy. For NGC 6951 we adopted the F547M and F814W observations, while for NGC 1512 we used the F438W and F555W images.…”

“…However, while this approach is well-established for point-source photometry, it breaks down for extended objects (see, e.g., de Grijs et al 2013a), unless one fully models the radial profiles (Anders et al 2006). To show this, we additionally adopted an adaptive aperture-photometry approach (de Grijs & Anders 2012;de Grijs et al 2013a;Li et al 2015), scaling the source apertures and sky annuli based on a measure of the objects' sizes (i.e., their Gaussian sizes, σG). We used a source aperture radius of 3σG, and 3.5σG and 5σG for the inner and outer sky annuli, respectively.…”