Podcasts about globular clusters

Chris and Shane welcome Peter Jedicke back to the show to talk about globular clusters.

New analysis of Cassini data suggests more complex hydrocarbons are part of Enceladus's global sub-surface ocean. We discuss the prospects for life on this tiny moon. The JWST continues to deliver scientific bonanzas, now providing direct observations of globular clusters in very distant galaxies, helping us understand these enigmatic and ancient structures. Join us to explore these mysteries and for space news and special down quark holiday-themed space trivia.

The dynamical state of the globular clusters Rup 106 and IC 4499 by Giacomo Beccari et al. on Wednesday 30 November The dynamical evolution of globular clusters is theoretically described by a series of well known events typical of N-body systems. Still, the identification of observational signatures able to empirically describe the stage of dynamical evolution of a stellar system of the density typical of a globular cluster, represents a challenge. In this paper we study the dynamical age of the globular clusters Rup 106 and IC 4499. To this aim, we study the radial distribution of the Blue Straggler Stars via the A+ parameter and of the slope of the Main Sequence Mass Function. Both tracers show that Rup 106 and IC 4499 are dynamically young clusters where dynamical friction has just started to segregate massive stars towards the clusters' centre. In fact, we observe that the Blue Straggler stars are more centrally concentrated in both clusters than the reference population. On the same line, we find that in both cases the slope of the mass function significantly decreases as a function of the cluster-centric distances. This result provides additional support for the use of the the radial distribution of the blue stragglers as a powerful observationally convenient indicator of the cluster dynamical age. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12884v2

The dynamical state of the globular clusters Rup 106 and IC 4499 by Giacomo Beccari et al. on Wednesday 30 November The dynamical evolution of globular clusters is theoretically described by a series of well known events typical of N-body systems. Still, the identification of observational signatures able to empirically describe the stage of dynamical evolution of a stellar system of the density typical of a globular cluster, represents a challenge. In this paper we study the dynamical age of the globular clusters Rup 106 and IC 4499. To this aim, we study the radial distribution of the Blue Straggler Stars via the A+ parameter and of the slope of the Main Sequence Mass Function. Both tracers show that Rup 106 and IC 4499 are dynamically young clusters where dynamical friction has just started to segregate massive stars towards the clusters' centre. In fact, we observe that the Blue Straggler stars are more centrally concentrated in both clusters than the reference population. On the same line, we find that in both cases the slope of the mass function significantly decreases as a function of the cluster-centric distances. This result provides additional support for the use of the the radial distribution of the blue stragglers as a powerful observationally convenient indicator of the cluster dynamical age. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12884v2

Stellar Escape from Globular Clusters I: Escape Mechanisms and Properties at Ejection by Newlin C. Weatherford et al. on Wednesday 30 November The theory of stellar escape from globular clusters (GCs) dates back nearly a century, especially the gradual evaporation of GCs via two-body relaxation coupled with external tides. More violent ejection can also occur via strong gravitational scattering, supernovae, gravitational wave-driven mergers, tidal disruption events, and physical collisions, but comprehensive study of the many escape mechanisms has been limited. Recent exquisite kinematic data from the Gaia space telescope has revealed numerous stellar streams in the Milky Way (MW) and traced the origin of many to specific MWGCs, highlighting the need for further examination of stellar escape from these clusters. In this study, the first of a series, we lay groundwork for detailed follow-up comparisons between Cluster Monte Carlo (CMC) GC models and the latest Gaia data on the outskirts of MWGCs, their tidal tails, and associated streams. We thoroughly review escape mechanisms from GCs and examine their relative contributions to the escape rate, ejection velocities, and escaper demographics. We show for the first time that three-body binary formation may dominate high-speed ejection from typical MWGCs, potentially explaining some of the hypervelocity stars in the MW. Due to their mass, black holes strongly catalyze this process, and their loss at the onset of observable core collapse, characterized by a steep central brightness profile, dramatically curtails three-body binary formation, despite the increased post-collapse density. We also demonstrate that even when born from a thermal eccentricity distribution, escaping binaries have significantly non-thermal eccentricities consistent with the roughly uniform distribution observed in the Galactic field. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16523v1

The dynamical state of the globular clusters Rup 106 and IC 4499 by Giacomo Beccari et al. on Wednesday 30 November The dynamical evolution of globular clusters is theoretically described by a series of well known events typical of N-body systems. Still, the identification of observational signatures able to empirically describe the stage of dynamical evolution of a stellar system of the density typical of a globular cluster, represents a challenge. In this paper we study the dynamical age of the globular clusters Rup 106 and IC 4499. To this aim, we study the radial distribution of the Blue Straggler Stars via the A+ parameter and of the slope of the Main Sequence Mass Function. Both tracers show that Rup 106 and IC 4499 are dynamically young clusters where dynamical friction has just started to segregate massive stars towards the clusters' centre. In fact, we observe that the Blue Straggler stars are more centrally concentrated in both clusters than the reference population. On the same line, we find that in both cases the slope of the mass function significantly decreases as a function of the cluster-centric distances. This result provides additional support for the use of the the radial distribution of the blue stragglers as a powerful observationally convenient indicator of the cluster dynamical age. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12884v2

Stellar Escape from Globular Clusters I: Escape Mechanisms and Properties at Ejection by Newlin C. Weatherford et al. on Wednesday 30 November The theory of stellar escape from globular clusters (GCs) dates back nearly a century, especially the gradual evaporation of GCs via two-body relaxation coupled with external tides. More violent ejection can also occur via strong gravitational scattering, supernovae, gravitational wave-driven mergers, tidal disruption events, and physical collisions, but comprehensive study of the many escape mechanisms has been limited. Recent exquisite kinematic data from the Gaia space telescope has revealed numerous stellar streams in the Milky Way (MW) and traced the origin of many to specific MWGCs, highlighting the need for further examination of stellar escape from these clusters. In this study, the first of a series, we lay groundwork for detailed follow-up comparisons between Cluster Monte Carlo (CMC) GC models and the latest Gaia data on the outskirts of MWGCs, their tidal tails, and associated streams. We thoroughly review escape mechanisms from GCs and examine their relative contributions to the escape rate, ejection velocities, and escaper demographics. We show for the first time that three-body binary formation may dominate high-speed ejection from typical MWGCs, potentially explaining some of the hypervelocity stars in the MW. Due to their mass, black holes strongly catalyze this process, and their loss at the onset of observable core collapse, characterized by a steep central brightness profile, dramatically curtails three-body binary formation, despite the increased post-collapse density. We also demonstrate that even when born from a thermal eccentricity distribution, escaping binaries have significantly non-thermal eccentricities consistent with the roughly uniform distribution observed in the Galactic field. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16523v1

Dynamics in the outskirts of four Milky Way globular clusters: it's the tides that dominate by Zhen Wan et al. on Wednesday 30 November We present the results of a spectroscopic survey of the outskirts of 4 globular clusters -- NGC 1261, NGC 4590, NGC 1904, and NGC 1851 -- covering targets within 1 degree from the cluster centres, with 2dF/AAOmega on the Anglo-Australian Telescope (AAT) and FLAMES on the Very Large Telescope (VLT). We extracted chemo-dynamical information for individual stars, from which we estimated the velocity dispersion profile and the rotation of each cluster. The observations are compared to direct $N$-body simulations and appropriate {sc limepy}/{sc spes} models for each cluster to interpret the results. In NGC 1851, the detected internal rotation agrees with existing literature, and NGC 1261 shows some rotation signal beyond the truncation radius, likely coming from the escaped stars. We find that the dispersion profiles for both the observations and the simulations for NGC 1261, NGC 1851, and NGC 1904 do not decrease as the {sc limepy}/{sc spes} models predict beyond the truncation radius, where the $N$-body simulations show that escaped stars dominate; the dispersion profile of NGC 4590 follows the predictions of the {sc limepy}/{sc spes} models, though the data do not effectively extend beyond the truncation radius. The increasing/flat dispersion profiles in the outskirts of NGC 1261, NGC 1851 and NGC 1904, are reproduced by the simulations. Hence, the increasing/flat dispersion profiles of the clusters in question can be explained by the tidal interaction with the Galaxy without introducing dark matter. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16659v1

Dynamics in the outskirts of four Milky Way globular clusters: it's the tides that dominate by Zhen Wan et al. on Wednesday 30 November We present the results of a spectroscopic survey of the outskirts of 4 globular clusters -- NGC 1261, NGC 4590, NGC 1904, and NGC 1851 -- covering targets within 1 degree from the cluster centres, with 2dF/AAOmega on the Anglo-Australian Telescope (AAT) and FLAMES on the Very Large Telescope (VLT). We extracted chemo-dynamical information for individual stars, from which we estimated the velocity dispersion profile and the rotation of each cluster. The observations are compared to direct $N$-body simulations and appropriate {sc limepy}/{sc spes} models for each cluster to interpret the results. In NGC 1851, the detected internal rotation agrees with existing literature, and NGC 1261 shows some rotation signal beyond the truncation radius, likely coming from the escaped stars. We find that the dispersion profiles for both the observations and the simulations for NGC 1261, NGC 1851, and NGC 1904 do not decrease as the {sc limepy}/{sc spes} models predict beyond the truncation radius, where the $N$-body simulations show that escaped stars dominate; the dispersion profile of NGC 4590 follows the predictions of the {sc limepy}/{sc spes} models, though the data do not effectively extend beyond the truncation radius. The increasing/flat dispersion profiles in the outskirts of NGC 1261, NGC 1851 and NGC 1904, are reproduced by the simulations. Hence, the increasing/flat dispersion profiles of the clusters in question can be explained by the tidal interaction with the Galaxy without introducing dark matter. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16659v1

Isochrone fitting of Galactic globular clusters -- IV NGC6362 and NGC6723 by George A. Gontcharov et al. on Thursday 24 November We present new isochrone fits to the colour-magnitude diagrams of the Galactic globular clusters NGC,6362 and NGC,6723. We utilize 22 and 26 photometric filters for NGC,6362 and NGC,6723, respectively, from the ultraviolet to mid-infrared using data sets from {it HST}, {it Gaia}, unWISE, and other photometric sources. We use models and isochrones from the Dartmouth Stellar Evolution Database (DSED) and Bag of Stellar Tracks and Isochrones (BaSTI) for $alpha$-enhanced [$alpha$/Fe]$=+0.4$ and different helium abundances. The metallicities [Fe/H]$=-1.04pm0.07$ and $-1.09pm0.06$ are derived from the red giant branch slopes in our fitting for NGC,6362 and NGC,6723, respectively. They agree with spectroscopic estimates from the literature. We find a differential reddening up to $Delta E(B-V)=0.13$ mag in the NGC,6723 field due to the adjacent Corona Australis cloud complex. We derive the following for NGC,6362 and NGC,6723, respectively: distances $7.75pm0.03pm0.15$ (statistic and systematic error) and $8.15pm0.04pm0.15$ kpc; ages $12.0pm0.1pm0.8$ and $12.4pm0.1pm0.8$ Gyr; extinctions $A_mathrm{V}=0.19pm0.04pm0.06$ and $0.24pm0.03pm0.06$ mag; reddenings $E(B-V)=0.056pm0.01pm0.02$ and $0.068pm0.01pm0.02$ mag. DSED provides systematically lower [Fe/H] and higher reddenings than BaSTI. However, the models agree in their relative estimates: NGC,6723 is $0.44pm0.04$ kpc further, $0.5pm0.1$ Gyr older, $Delta E(B-V)=0.007pm0.002$ more reddened, and with $0.05pm0.01$ dex lower [Fe/H] than NGC,6362. The lower metallicity and greater age of NGC,6723 with respect to NGC,6362 explain their horizontal branch morphology difference. This confirms age as the second parameter for these clusters. We provide lists of the cluster members from the {it Gaia} Data Release 3. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12684v1

The dynamical state of the globular clusters Rup 106 and IC 4499 by Giacomo Beccari et al. on Thursday 24 November The dynamical evolution of globular clusters is theoretically described by a series of well known events typical of N-body systems. Still, the identification of observational signatures able to empirically describe the stage of dynamical evolution of a stellar system of the density typical of a globular cluster, represents a challenge. In this paper we study the dynamical age of the globular clusters Rup 106 and IC 4499. To this aim, we study the radial distribution of the Blue Straggler Stars via the A+ parameter and of the slope of the Main Sequence Mass Function. Both tracers show that Rup 106 and IC 4499 are dynamically young clusters where dynamical friction has just started to segregate massive stars towards the clusters' centre. In fact, we observe that the Blue Straggler stars are more centrally concentrated in both clusters than the reference population. On the same line, we find that in both cases the slope of the mass function significantly decreases as a function of the cluster-centric distances. This result provides additional support for the use of the the radial distribution of the blue stragglers as a powerful observationally convenient indicator of the cluster dynamical age. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12884v1

The dynamical state of the globular clusters Rup 106 and IC 4499 by Giacomo Beccari et al. on Wednesday 23 November The dynamical evolution of globular clusters is theoretically described by a series of well known events typical of N-body systems. Still, the identification of observational signatures able to empirically describe the stage of dynamical evolution of a stellar system of the density typical of a globular cluster, represents a challenge. In this paper we study the dynamical age of the globular clusters Rup 106 and IC 4499. To this aim, we study the radial distribution of the Blue Straggler Stars via the A+ parameter and of the slope of the Main Sequence Mass Function. Both tracers show that Rup 106 and IC 4499 are dynamically young clusters where dynamical friction has just started to segregate massive stars towards the clusters' centre. In fact, we observe that the Blue Straggler stars are more centrally concentrated in both clusters than the reference population. On the same line, we find that in both cases the slope of the mass function significantly decreases as a function of the cluster-centric distances. This result provides additional support for the use of the the radial distribution of the blue stragglers as a powerful observationally convenient indicator of the cluster dynamical age. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12884v1

Isochrone fitting of Galactic globular clusters -- IV NGC6362 and NGC6723 by George A. Gontcharov et al. on Wednesday 23 November We present new isochrone fits to the colour-magnitude diagrams of the Galactic globular clusters NGC,6362 and NGC,6723. We utilize 22 and 26 photometric filters for NGC,6362 and NGC,6723, respectively, from the ultraviolet to mid-infrared using data sets from {it HST}, {it Gaia}, unWISE, and other photometric sources. We use models and isochrones from the Dartmouth Stellar Evolution Database (DSED) and Bag of Stellar Tracks and Isochrones (BaSTI) for $alpha$-enhanced [$alpha$/Fe]$=+0.4$ and different helium abundances. The metallicities [Fe/H]$=-1.04pm0.07$ and $-1.09pm0.06$ are derived from the red giant branch slopes in our fitting for NGC,6362 and NGC,6723, respectively. They agree with spectroscopic estimates from the literature. We find a differential reddening up to $Delta E(B-V)=0.13$ mag in the NGC,6723 field due to the adjacent Corona Australis cloud complex. We derive the following for NGC,6362 and NGC,6723, respectively: distances $7.75pm0.03pm0.15$ (statistic and systematic error) and $8.15pm0.04pm0.15$ kpc; ages $12.0pm0.1pm0.8$ and $12.4pm0.1pm0.8$ Gyr; extinctions $A_mathrm{V}=0.19pm0.04pm0.06$ and $0.24pm0.03pm0.06$ mag; reddenings $E(B-V)=0.056pm0.01pm0.02$ and $0.068pm0.01pm0.02$ mag. DSED provides systematically lower [Fe/H] and higher reddenings than BaSTI. However, the models agree in their relative estimates: NGC,6723 is $0.44pm0.04$ kpc further, $0.5pm0.1$ Gyr older, $Delta E(B-V)=0.007pm0.002$ more reddened, and with $0.05pm0.01$ dex lower [Fe/H] than NGC,6362. The lower metallicity and greater age of NGC,6723 with respect to NGC,6362 explain their horizontal branch morphology difference. This confirms age as the second parameter for these clusters. We provide lists of the cluster members from the {it Gaia} Data Release 3. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12684v1

Linking the Internal Properties of Infant Globular Clusters to their Formation Environments by Frederika Phipps et al. on Monday 21 November We investigate the formation of infant globular cluster (GC) candidates in high-resolution cosmological simulations from the First Billion Years (FiBY) project. By analysing the evolution of the systems in the energy and angular momentum plane, we identify the redshift at which the infant GCs first became gravitationally bound, and we find evidence of radial infall of their gaseous and stellar components. The collapse appears to be driven by internal self-gravity, however, the initial trigger is sourced from the external environment. The phase space behaviour of the infant GCs also allows us to identify some characteristic groupings of objects. Such a classification based on internal properties appears to be reflected in the formation environment: GC candidates that belong to the same class are found in host galaxies of similar morphology, with the majority of the infant GCs located in clumpy, irregular proto-galaxies. Finally, through the inspection of two GC candidates that contain only stars by z = 6, we find that supernova feedback is the main physical mechanism behind their dearth of gas and that the systems subsequently respond with an approximately adiabatic expansion. Such infant GC candidates already resemble the GCs we currently observe in the local Universe. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.09583v1

The quest to understand the formation mechanisms of globular clusters was limited by the Hubble Space Telescope's ability to peer back in time. Now, JWST's larger mirror has allowed astronomers to find gravitationally lensed galaxies that have globular clusters almost nine billion years old. Plus, two new super-mercury exoplanets, This Week in Space History, and an interview with Eric Palmer about the DART mission.   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs.  Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too!  Every bit helps! Thank you! ------------------------------------ Do go visit http://www.redbubble.com/people/CosmoQuestX/shop for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations.  Thank you! (Haven't donated? It's not too late! Just click!) ------------------------------------ The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. http://www.psi.edu Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.

The quest to understand the formation mechanisms of globular clusters was limited by the Hubble Space Telescope's ability to peer back in time. Now, JWST's larger mirror has allowed astronomers to find gravitationally lensed galaxies that have globular clusters almost nine billion years old. Plus, two new super-mercury exoplanets, This Week in Space History, and an interview with Eric Palmer about the DART mission.   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs.  Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too!  Every bit helps! Thank you! ------------------------------------ Do go visit http://www.redbubble.com/people/CosmoQuestX/shop for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations.  Thank you! (Haven't donated? It's not too late! Just click!) ------------------------------------ The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. http://www.psi.edu Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.

Detection of Intracluster Globular Clusters in the First JWST Images of the Gravitational Lens Cluster SMACS J0723 3-7327 at z = 0 39 by Myung Gyoon Lee et al. on Wednesday 12 October We present a survey of globular clusters (GCs) in the massive gravitational lens cluster SMACS J0723.3-7327 at $z=0.39$ based on the early released JWST/NIRCam images. In the color-magnitude diagrams of the point sources we find clearly a rich population of intracluster GCs that spread in a wide area of the cluster. Their ages, considering the cluster redshift, are younger than 9.5 Gyr. The F200W (AB) magnitudes of these GCs, $26.5

Prospects for Detecting Fast Radio Bursts in Globular Clusters of Nearby Galaxies by Kyle Kremer et al. on Tuesday 11 October The recent detection of a repeating fast radio burst (FRB) in an old globular cluster in M81 challenges traditional FRB formation mechanisms based on magnetic activity in young neutron stars formed recently in core-collapse supernovae. Furthermore, the detection of this repeater in such a nearby galaxy implies a high local universe rate of similar events in globular clusters. Building off the properties inferred from the M81 FRB, we predict the number of FRB sources in nearby ($d lesssim 20,$Mpc) galaxies with large globular cluster systems known. Incorporating the uncertain burst energy distribution, we estimate the rate of bursts detectable in these galaxies by radio instruments such as FAST and MeerKat. Of all local galaxies, we find M87 is the best candidate for FRB detections. We predict M87's globular cluster system contains $mathcal{O}(10)$ FRB sources at present and that a dedicated radio survey (by FAST) of $mathcal{O}(10),$hr has a $90%$ probability of detecting a globular cluster FRB in M87. The detection of even a handful of additional globular cluster FRBs would provide invaluable constraints on FRB mechanisms and population properties. Previous studies have demonstrated young neutron stars formed following collapse of dynamically-formed massive white dwarf binary mergers may provide the most natural mechanism for these bursts. We explore the white dwarf merger scenario using a suite of $N$-body cluster models, focusing in particular on such mergers in M87 clusters. We describe a number of outstanding features of this scenario that in principle may be testable with an ensemble of observed FRBs in nearby globular clusters. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2210.04907v1

The distribution of globular clusters in kinematic spaces does not trace the accretion history of the host galaxy by Giulia Pagnini et al. on Monday 10 October Reconstructing how all the stellar components of the Galaxy formed and assembled over time, by studying the properties of the stars which make it, is the aim of Galactic archeology. In these last years, thanks to the launch of the ESA Gaia astrometric mission, and the development of many spectroscopic surveys, we are for the first time in the position to delve into the layers of the past of our galaxy. Globular clusters (GCs) play a fundamental role in this research field since they are among the oldest stellar systems in the Milky Way (MW) and so bear witness of its entire past. In the recent years, there have been several attempts to constrain the nature of clusters (accreted or formed in the MW itself) through the analysis of kinematic spaces and to reconstruct from this the properties of the accretions events experienced by the MW through time. This work aims to test a widely-used assumption about the clustering of the accreted populations of GCs in the integrals of motions space. We analyze a set of dissipation-less N-body simulations that reproduce the accretion of one or two satellites with their GC population on a MW-type galaxy. Our results demonstrate that a significant overlap between accreted and "kinematically-heated" in-situ GCs is expected in kinematic spaces, for mergers with mass ratios of 1:10. In contrast with standard assumptions made in the literature so far, we find that accreted GCs do not show dynamical coherence, that is they do not cluster in kinematic spaces. In addition, GCs can also be found in regions dominated by stars which have a different origin (i.e. different progenitor). This casts doubt on the association between GCs and field stars that is generally made in the literature to assign them to a common origin. Our findings severely question the recovered accretion history of the MW based on the phase-space clustering of the GC population. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2210.04245v1

The quest to understand the formation mechanisms of globular clusters was limited by the Hubble Space Telescope's ability to peer back in time. Now, JWST's larger mirror has allowed astronomers to find gravitationally lensed galaxies that have globular clusters almost nine billion years old. Plus, two new super-mercury exoplanets, This Week in Space History, and an interview with Eric Palmer about the DART mission.

Modeling globular clusters in the TNG50 simulation: predictions from dwarfs to giants by Jessica E. Doppel et al. on Monday 26 September We present a post-processing catalog of globular clusters (GCs) for the $39$ most massive groups and clusters in the TNG50 simulation of the IlllustrisTNG project (virial masses $M_{200} =[5times 10^{12} rm - 2 times 10^{14}$] M$_{odot}$). We tag GC particles to all galaxies with stellar mass $M_* geq 5times10^6$ M$_{odot}$, and we calibrate their masses to reproduce the observed power-law relation between GC mass and halo mass for galaxies with $M_{200} geq 10^{11}$ M$_{odot}$ (corresponding to $M_* sim 10^9$ $M_{odot}$). Here we explore whether an extrapolation of this $M_{rm GC}$-$M_{200}$ relation to lower-mass dwarfs is consistent with current observations. We find a good agreement between our predicted number and specific frequency of GCs in dwarfs with $rm M_*=[5 times 10^6 rm - 10^9]$ M$_{odot}$ and observations. Moreover, we predict a steep decline in the GC occupation fraction for dwarfs with $M_*

Modeling globular clusters in the TNG50 simulation: predictions from dwarfs to giants by Jessica E. Doppel et al. on Monday 26 September We present a post-processing catalog of globular clusters (GCs) for the $39$ most massive groups and clusters in the TNG50 simulation of the IlllustrisTNG project (virial masses $M_{200} =[5times 10^{12} rm - 2 times 10^{14}$] M$_{odot}$). We tag GC particles to all galaxies with stellar mass $M_* geq 5times10^6$ M$_{odot}$, and we calibrate their masses to reproduce the observed power-law relation between GC mass and halo mass for galaxies with $M_{200} geq 10^{11}$ M$_{odot}$ (corresponding to $M_* sim 10^9$ $M_{odot}$). Here we explore whether an extrapolation of this $M_{rm GC}$-$M_{200}$ relation to lower-mass dwarfs is consistent with current observations. We find a good agreement between our predicted number and specific frequency of GCs in dwarfs with $rm M_*=[5 times 10^6 rm - 10^9]$ M$_{odot}$ and observations. Moreover, we predict a steep decline in the GC occupation fraction for dwarfs with $M_*

The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I by Steven R. Janssens et al. on Wednesday 21 September We investigate the isolated, quiescent ultra-diffuse galaxy (UDG) DGSAT I and its globular cluster (GC) system using two orbits of Hubble Space Telescope Advanced Camera for Surveys imaging in the F606W and F814W filters. This is the first study of GCs around a UDG in a low-density environment. DGSAT I was previously found to host an irregular blue low surface brightness clump, that we confirm as very likely belonging to the galaxy rather than being a chance projection, and represents a recent episode of star formation (${sim}500~mathrm{Myr}$) that challenges some UDG formation scenarios. We select GC candidates based on colours and magnitudes, and construct a self consistent model of the GC radial surface density profile along with the background. We find a half-number radius of $R_mathrm{GC} = 2.7pm0.1~mathrm{kpc}$ (more compact than the diffuse starlight) and a total of $12 pm 2$ GCs. The total mass fraction in GCs is relatively high, supporting an overmassive dark matter halo as also implied by the high velocity dispersion previously measured. The GCs extend to higher luminosities than expected, and have colours that are unusually similar to their host galaxy colour, with a very narrow spread--all of which suggest an early, intense burst of cluster formation. The nature and origin of this galaxy remain puzzling, but the most likely scenario is a "failed galaxy" that formed relatively few stars for its halo mass, and could be related to cluster UDGs whose size and quiescence pre-date their infall. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.09910v1

The role of rotation on the formation of second generation stars in globular clusters by Elena Lacchin et al. on Monday 12 September By means of 3D hydrodynamic simulations, we explore the effects of rotation in the formation of second-generation (SG) stars in globular clusters (GC). Our simulations follow the SG formation in a first-generation (FG) internally rotating GC; SG stars form out of FG asymptotic giant branch (AGB) ejecta and external pristine gas accreted by the system. We have explored two different initial rotational velocity profiles for the FG cluster and two different inclinations of the rotational axis with respect to the direction of motion of the external infalling gas, whose density has also been varied. For a low (10^-24 g cm^-3) external gas density, a disk of SG helium-enhanced stars is formed. The SG is characterized by distinct chemo-dynamical phase space patterns: it shows a more rapid rotation than the FG with the helium-enhanced SG subsystem rotating more rapidly than the moderate helium-enhanced one. In models with high external gas density (10^-23 g cm^-3), the inner SG disc is disrupted by the early arrival of external gas and only a small fraction of highly enhanced helium stars preserves the rotation acquired at birth. Variations in the inclination angle between the rotation axis and the direction of the infalling gas and the velocity profile can slightly alter the extent of the stellar disc and the rotational amplitude. No significant variation has been found in the timespan of our simulations when changing the inclination angle between the rotation axis and the direction of the infalling gas, while different velocity profiles can slightly alter the extent of the stellar disc and the rotational amplitude. The results of our simulations illustrate the complex link between dynamical and chemical properties of multiple populations and provide new elements for the interpretation of observational studies and future investigations of the dynamics of multiple-population GCs. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.05178v1

Nonlinear Color-Metallicity Relations of Globular Clusters XI Nonlinearity Effect Revealed by NGC 5128 Centaurus A and NGC 4594 Sombrero Galaxies by Hak-Sub Kim et al. on Wednesday 07 September Metallicity distributions (MDs) of globular clusters (GCs) provide crucial clues for the assembly and star formation history of their host galaxies. GC colors, when GCs are old, have been used as a proxy of GC metallicities. Bimodal GC color distributions (CDs) observed in most early-type galaxies have been interpreted as bimodal MDs for decades, suggesting the presence of merely two GC subpopulations within single galaxies. However, the conventional view has been challenged by a new theory that nonlinear metallicity-to-color conversion can cause bimodal CDs from unimodal MDs. The unimodal MDs seem natural given that MDs involved many thousand protogalaxies. The new theory has been tested and corroborated by various observational and theoretical studies. Here we examine the nonlinear nature of GC color-metallicity relations (CMRs) using photometric and spectroscopic GC data of NGC 5128 (Centaurus A) and NGC 4594 (Sombrero), in comparison with stellar population simulations. We find that, with a slight offset in color, the overall shapes of observed and modeled CMRs agree well for all available colors. Diverse color-depending morphologies of GC CDs of the two galaxies are well reproduced based on their observed spectroscopic MDs via our CMR models. The results corroborate the nonlinear CMR interpretation of the GC color bimodality, shedding further light on theories of galaxy formation. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.02738v1

Welcome to the SHOT with CwC where we all take a shot and tell a brief story about one of the universe's many topics! In this episode, Mike talks about Globular Clusters and the importance of understanding galaxy formation through the study of these huge bundles of stars. Grab a shot and cheers to old stars with new tricks. *Always Drink Responsibly* Listen and Subscribe to us on: Anchor.fm Spotify YouTube Apple Podcasts Google Podcasts Cosmoswithcosmos.com Follow Us! Twitter: @drinkingcosmos Instagram: @cosmoswithcosmos Credits: Eric Skiff - Resistor Anthems http://EricSkiff.com/music Theme Music Remixed by: Ron Proctor https://www.youtube.com/channel/UC__fjzKFm0X0BQWHjYX8Z_w

JOIN OUR DISCORD: https://discord.gg/8DmFBmMA63  There had been a plan for this episode, and it was quickly thrown out the window when we asked the Trailcasters Discord for any questions and our fam went OFF. Keith & Chris covered some distance in this episode, including but not limited to... - Love, Hugs & Hatemail: AAPI Heritage Month, JJ Redick, Dillon Brooks & more - Rogue 1 is the best Star Wars movie & ET was not a Jedi - Favorite food in the Rose Garden & where to watch outside it - Best parts of a Blazers-less postseason - How can Blazers "win" the Hart/CJ trade? - Fit vs Future: Josh Hart & Penny Simons - Judging Billups' first year as HC - If we colonized the moon... JOIN OUR DISCORD: https://discord.gg/8DmFBmMA63  Hit us up on Discord, @trailcasters on Twitter & Reddit, or email trailcasters@gmail.com and if you can share opinions on what you like, dislike, or which directions we should expand on, we'll do our best to make it happen! For more of our music, you can find Odar's beats at soundcloud.com/odarbeats And if you have any need of their services, PLEASE support clearlyspeakingoregon.com like they've supported our podcast from the beginning! Enjoy the episode and GO BLAZERS!!!

How are globular clusters so old? Where did they come from, and how are they linked to galaxy formation? What makes them so globular, anyway? I discuss these questions and more in today's Ask a Spaceman!   Support the show: http://www.patreon.com/pmsutter All episodes: http://www.AskASpaceman.com Follow on Twitter: http://www.twitter.com/PaulMattSutter Like on Facebook: http://www.facebook.com/PaulMattSutter Watch on YouTube: http://www.youtube.com/PaulMSutter Read a book: http://www.pmsutter/book Go on an adventure: http://www.AstroTours.co   Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE! Big thanks to my top Patreon supporters this month: Justin G, Chris L, Barbara K, Duncan M, Corey D, Justin Z, Nate H, Andrew F, Naila, Aaron S, Scott M, Rob H, Lowell T, Justin, Louis M, Paul G, John W, Alexis, Erin J, Jennifer M, Gilbert M, Tom B, Joshua, Curt M, David B, Frank T, Tim R, Tom Van S, Mark R, Alan B, Craig B, Richard K, Steve P, Dave L, Chuck C, Stephen M, Maureen R, Stace J, Neil P, lothian53, COTFM, Stephen S, Ken L, Debra S, Alberto M, Matt C, Ron S, Joe R, Jeremy K, David P, Ulfert B, Robert B, Fr. Bruce W, Nicolai B, Sean M, Edward K, Darren W, Tracy F, Sarah K, Bill H, Steven S, Ryan L, Ella F, Richard S, Sam R, Thomas K, James C, Jorg D, R Larche, Syamkumar M, John S, Fred S, Homer V, Mark D, Brianna V, Colin B, Bruce A, Steven M, Brent B, Bill E, Tim Z, Thomas W, Linda C, David W, Aissa F, Marc H, Avery P, Scott M, Katelyn, Thomas H, Farshad A, Matthias S, Kenneth D, Maureen R, Michael W, Scott W, David W, Neuterdude, Cha0sKami, Brett, Robert C, Matthew K, Robert B, Gary K, Stephen J, dhr18, Anna V, Johanna M, Matthew G, Paul & Giulia S, Dr. D, Ron D, Steven M, Louis M, and Michael C! Thanks to Cathy Rinella for editing. Hosted by Paul M. Sutter, astrophysicist and the one and only Agent to the Stars  http://www.pmsutter.com   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs.  Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too!  Every bit helps! Thank you! ------------------------------------ Do go visit http://www.redbubble.com/people/CosmoQuestX/shop for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations.  Thank you! (Haven't donated? It's not too late! Just click!) ------------------------------------ The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. http://www.psi.edu Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.

How are globular clusters so old? Where did they come from, and how are they linked to galaxy formation? What makes them so globular, anyway? I discuss these questions and more in today's Ask a Spaceman! Support the show: http://www.patreon.com/pmsutter All episodes: http://www.AskASpaceman.com Follow on Twitter: http://www.twitter.com/PaulMattSutter Like on Facebook: http://www.facebook.com/PaulMattSutter Watch on YouTube: http://www.youtube.com/PaulMSutter Read a book: http://www.pmsutter/book Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE! Big thanks to my top Patreon supporters this month: Justin G, Chris L, Barbara K, Duncan M, Corey D, Justin Z, Nate H, Andrew F, Naila, Aaron S, Scott M, Rob H, Lowell T, Justin, Louis M, Paul G, John W, Alexis, Erin J, Jennifer M, Gilbert M, Tom B, Joshua, Curt M, David B, Frank T, Tim R, Tom Van S, Mark R, Alan B, Craig B, Richard K, Steve P, Dave L, Chuck C, Stephen M, Maureen R, Stace J, Neil P, lothian53, COTFM, Stephen S, Ken L, Debra S, Alberto M, Matt C, Ron S, Joe R, Jeremy K, David P, Ulfert B, Robert B, Fr. Bruce W, Nicolai B, Sean M, Edward K, Darren W, Tracy F, Sarah K, Bill H, Steven S, Ryan L, Ella F, Richard S, Sam R, Thomas K, James C, Jorg D, R Larche, Syamkumar M, John S, Fred S, Homer V, Mark D, Brianna V, Colin B, Bruce A, Steven M, Brent B, Bill E, Tim Z, Thomas W, Linda C, David W, Aissa F, Marc H, Avery P, Scott M, Katelyn, Thomas H, Farshad A, Matthias S, Kenneth D, Maureen R, Michael W, Scott W, David W, Neuterdude, Cha0sKami, Brett, Robert C, Matthew K, Robert B, Gary K, Stephen J, dhr18, Anna V, Johanna M, Matthew G, Paul & Giulia S, Dr. D, Ron D, Steven M, Louis M, and Michael C! Thanks to Cathy Rinella for editing. Hosted by Paul M. Sutter, astrophysicist and the one and only Agent to the Stars (http://www.pmsutter.com).

Welcome to the Music Tas Podcast. In this episode, we hear from the Sisters Akousmatica. Their expanded radio projects explore radical transmission possibilities through voice, radio receivers and transmitters, amplified mineral samples, re-kindled transistor parts, pulsar, wind, waves, and words. Recently they drove their Broom Broom vehicle of transmission at Junction Festival in various public spaces, where audiences could draw on the car and take control of hyperlocal airwaves. They also have a Borderadio artwork presented at the group exhibition Shaping the Aether at the espace multimedia Gantner in France curated by Pali Meursault.The nipaluna/Hobart based radio queens share some recordings concerned with collective electromagnetic practices and ownership of the airwaves located in high magnetic latitude in the southern hemisphere. They interview Dr Warren Hankey, a PhD on globular clusters at the Grote Reber Museum and a member of The Sound Preservation Association of Tasmania team, who shares their knowledge of radio waves lutruwita-Tasmania.  In the conversation, they talk about an impromptu sewage sound, and lament a horde of musical wind creatures.In this episode, all sounds were researched, performed, and recorded on the unceded land of the palawa people between 2017 and 2021.

Daniel and guest host Katie Goldin explore the mysteries of these weird, ancient blobs of stars. Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

Bio: Cosmic (aka Matt Cheselka / @AstroAndMusic ) is an independent research astronomer and space musician. Description: Cosmic discusses the study of stars being ejected from globular clusters, and how these tidal tails are formed by internal and external forces. Bonaca et al -- https://arxiv.org/pdf/1910.00592.pdf Combes et al -- https://arxiv.org/pdf/astro-ph/9910148.pdf Michie -- http://articles.adsabs.harvard.edu/pdf/1963MNRAS.125..127M Woolley & Robertson -- http://articles.adsabs.harvard.edu/pdf/1956MNRAS.116..288W   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs. Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too! Every bit helps! Thank you! ------------------------------------ Do go visit http://astrogear.spreadshirt.com/ for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations. Thank you! (Haven't donated? It's not too late! Just click!) The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. http://www.astrosphere.org/ Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.

A conversation with Astronomer Caty Pilachowski, about diversity in the sciences, the future of telescopes, and the beginning of everything.

In this week's questions show, I answer a question about solar sails, what geologists might learn from lunar rocks, if Earth could survive inside Jupiter, could gas giants be closer to the Sun, and more. Dark Site Finder: https://darksitefinder.com/map/ Videos mentioned: What is an Electric Sail? Another Exotic Way to Explore the Solar System - https://youtu.be/-pIl_cv3OkA Oldest Rock From Earth Was Found On The Moon (Of All Places) - https://youtu.be/0h_ckjhGdjs What are Globular Clusters? Relics of the Early Universe - https://youtu.be/BjzptXhpsz8 Timecodes: 00:15 Solar sails to the outer Solar System? 01:57 What could geologists learn from more lunar rocks? 04:01 Could Earth survive inside Jupiter? 05:49 Would gas giants change if they were closer to the Sun? 08:01 What if aliens have different laws of physics? 10:19 Best places to put a telescope 12:03 Difference between globular clusters and dwarf galaxies 13:31 Water shielding for a rover 15:16 Do I play RPGs 17:32 Should science be outcome-based? 19:33 Could you orbit the Moon more closely? 21:17 Site to avoid light pollution Want to be part of the questions show? Ask a short question on any video on my channel. I gather a bunch up each week, and answer them here. Our Book is out! https://www.amazon.com/Universe-Today-Ultimate-Viewing-Cosmos/dp/1624145442/ Audio Podcast version: ITunes: https://itunes.apple.com/us/podcast/universe-today-guide-to-space-audio/id794058155?mt=2 RSS: https://www.universetoday.com/audio What Fraser's Watching Playlist: https://www.youtube.com/playlist?list=PLbJ42wpShvmkjd428BcHcCEVWOjv7cJ1G Weekly email newsletter: https://www.universetoday.com/newsletter Weekly Space Hangout: https://www.youtube.com/channel/UC0-KklSGlCiJDwOPdR2EUcg/ Astronomy Cast: https://www.youtube.com/channel/UCUHI67dh9jEO2rvK--MdCSg Support us at: http://www.patreon.com/universetoday More stories at: http://www.universetoday.com/ Twitch: https://twitch.tv/fcain Follow us on Twitter: @universetoday Like us on Facebook: https://www.facebook.com/universetoday Instagram - https://instagram.com/universetoday Team: Fraser Cain - @fcain / frasercain@gmail.com Karla Thompson - @karlaii / https://www.youtube.com/channel/UCEItkORQYd4Wf0TpgYI_1fw Chad Weber - weber.chad@gmail.comSupport Universe Today Podcast

Is it globular clusters or is it globeular clusters? It doesn't matter, they're awesome and we're here to update you on them.

497: Update on Globular Clusters Astronomy Cast 497: Update on Globular Clusters by Fraser Cain & Dr. Pamela Gay

A serving of Globular Clusters and Amanda's favourite milkshake (it's not chocolate).

One of the most beautiful and scientifically interesting objects in space are the globular clusters, containing hundreds of thousands of stars. What are they and where did they come from?Support Universe Today Podcast

One of the most beautiful and scientifically interesting objects in space are the globular clusters, containing hundreds of thousands of stars. What are they and where did they come from?

This week in Rhubarb and Sam, astronomy! We set-up at the Tucker Creek observatory for some time at the telescope only to have a clear night turn into a not-so-clear night due to high humidity. The stars were still pretty bright in our dark skies so we settled in on the moon couch (our disc shaped outdoor couch) to record an episode. From Cygnus to Sagittarius, Saturn to Mars, take a tour of our night sky with us. There's nothing quite like pondering our place in our galaxy and our galaxy's place in the Universe. Have a listen! Links of interest:Our Milky Way GalaxyOur Solar SystemGlobular Clusters Please note that you can subscribe to the podcast in several ways:At the iTunes store via this link.If you are using an RSS reader or podcast app use this link.Thanks and enjoy!

This work is focused on the search for intermediate-mass black holes (IMBHs) in the centers of globular clusters. It has been demonstrated that supermassive black holes (SMBHs) at the centers of galaxies show a tight correlation between their mass (M•) and the velocity dispersion (σ) of the galaxy. Investigating this M• − σ and similar correlations is crucial to constrain scenarios of galaxy formation and evolution. If they formed by runaway collisions of massive stars in young and dense stellar clusters, IMBHs could still be present in the centers of globular clusters, today. We measured the inner kinematic profiles for a sample of 9 galactic globular clusters using integral-field spectroscopy and combined them with existing outer kinematics and photom- etry obtained form HST archive images. In order to constrain the mass of a possible black hole we applied analytical Jeans models in combinations with varying M/LV profiles to each of the clusters. The results of these fits range from strong hints towards an IMBH (e.g. NGC 6388) to globular clusters which do not show any indications of a rising velocity dis- persion profile in their center (e.g. NGC 2808). Furthermore, the discovery of two high velocity stars in NGC 2808 opened another opportunity to study the internal kinematics of this particular cluster and indicates a high number of stellar-mass black holes in NGC 2808. We finally combined our results with measurements from the literature and investigated known scaling relations for SMBHs in galaxies (e.g. M• − σ) at the low-mass end by plac- ing the results and upper limits of IMBH measurements on these correlations. We found that IMBHs follow similar, but more shallow correlations of their mass and the properties of their host systems. This might be caused with the severe mass-loss the cluster suffers during its life time. In addition we ran numerical N-body simulations and compared globular clusters with dif- ferent black-hole retention fractions, IMBH masses and binary fractions. We found that IMBHs lead to a higher ejection rate of massive stars so that clusters with less depleted mass functions might therefore be good candidates to host IMBHs at their centers. In the future more N-body simulations will be performed in order to reproduce our observations in a more sophisticated way and perform crucial tests to our observing and analysis methods. The search for IMBHs requires both high spatial and spectral resolution and will remain at the edge of feasibility. However, it is crucial to continue the investigations in order to shed light on black-hole formation and growth.

Transcript: The ages of stars are derived from stellar models. The physics is complex so computers are used to simulate energy transport mechanisms. The details depend on heavy element abundance and on the mechanism for helium diffusion in the atmosphere of the stars. Thus there are uncertainties attached to the prediction of luminosity from stellar models. There are also uncertainties attached to the determination of luminosity from observation of stars. This can include the effect of interstellar extinction and uncertainties in the distance estimates. Since luminosity is proportional to distance squared, a ten percent error in the distance leads to a twenty percent error in luminosity. For all of these reasons it’s difficult to measure ages more accurately than ten or twenty percent.

Thu, 10 Jun 2010 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/12383/ https://edoc.ub.uni-muenchen.de/12383/1/Huang_Hsiu-Hui.pdf Huang, Hsiu-Hui ddc:530, ddc:500, Fakultät für Physik

Astronomer Scott Ransom has discovered 30 pulsars and counting in a globular cluster known as Terzan 5. Learn more about these bizarre spinning neutron stars.

The work presented here deals with the age structure in globular cluster systems of early-type galaxies and aims at further clues about the formation and evolution of these galaxies. Hereby we turn our attention mainly to the detection of age sub-populations within the globular cluster systems, which are a clear signature of multiple star formation events and describe the major phases in the evolutionary history of the host galaxy. The basic ingredients to our semi-numerical approach are combined optical and near-infrared observations of various globular cluster systems and Single Stellar Population models. Besides the introduction and the test of our semi-numerical method of deriving the age structure in globular cluster systems we are also interested in investigating an extended galaxy sample, i.e. their globular cluster systems in order to find systematic dependencies of the age structure. Since Single Stellar Population models are crucial for our project and various of these models are available we also to evcaluate the influence of our choice of SSP model on the final result.