Date: Mon, 7 Apr 2003 17:08:13 +0100 (BST) From: Richard de Grijs Dear Roberto, Here is the info I have collected for the UK node of the proposed network. Unfortunately, only Stephen Smartt has provided some minimal info, so there is not much in addition to what I sent you myself some time ago. This is what we'll have to work with for now, however. Richard Coordinator: Richard de Grijs (grijs@ast.cam.ac.uk) (Sheffield) Proposed collaborators: - Gerry Gilmore (gil@ast.cam.ac.uk) (Cambridge) - Stephen Smartt (sjsast.cam.ac.uk) (Cambridge) - Linda Smith (ljs@star.ucl.ac.uk) (UCL) - Ian Bonnell (iab1@st-andrews.ac.uk) (St. Andrews) Possible additional collaborators: - Paul Crowther (Sheffield) - Vik Dhillon (Sheffield) Expertise: (de Grijs and Smartt ONLY; no further information received from other collaborators) - Star cluster formation in the intense environments of interacting and starburst galaxies. Star cluster formation seems to be a (if not the) major mode of star formation in the extreme environments found in interacting and starburst galaxies. As such, they trace the major stages of galaxy formation and evolution. The main objective of our research at Sheffield is to use the young and intermediate-age star clusters as tracers of galaxy evolution and to determine whether they have the potential to evolve into old Galactic globular cluster-type objects by the time they reach similar ages. If so, this implies that globular cluster formation did not only happen at the time of galaxy fornation, but continues until the present. If we can establish this scenario beyond a doubt, this will have far-reaching consequences for theories of galaxy formation and evolution. These questions can most easily be addressed using the star cluster luminosity (or mass) functions in conjunction with models for the evolution of star cluster SYSTEMS. Alternatively, we are engaged in a number of projects in which we try to determine the stellar initial mass function (IMF) based on high-resolution spectroscopy (HST/STIS, VLT/UVES). The slope of the IMF is the most crucial ingredient for the evolution and survivability of an individual cluster Specific expertise offered at Sheffield is predominantly of observational and interpretational nature. We have developed techniques to use multi-passband imaging observations (mainly taken with the high resolution offered by the Hubble Space Telescope, but applicable to ground-based efforts as well) to simultaneously determine ages, masses, metallicities and indeed extinction values for individual star clusters. These techniques have been applied successfully to a number of interacting and starburst galaxies, including M82, NGC 3310, M51, NGC 6745, NGC 1569, among others. High-resolution spectroscopy is used to determine dynamical cluster masses, and in combination with HST imaging, their mass-to-light ratios, which are then compared to models using a variety of prescriptions for the evolution of single stellar populations with certain IMF parameters. - The internal dynamics of star clusters Rich, compact star clusters are the ideal laboratories for the study of stellar evolution. As such, the old globular clusters (GCs) in the Milky Way have been used extensively for this purpose, and their colour-magnitude diagrams (CMDs) are now well understood. However, the evolution of the dynamically important binary population is not yet well understood. Although the Milky Way contains a large population of GCs, they are predominantly old, with ages largely in excess of 10 Gyr. Therefore, we cannot use the Galactic GC population to follow the evolution of binary systems in the dense environments of GC-type objects. Fortunately, however, we have access to a unique data set of deep HST observations of a carefully selected sample of similar star clusters in the Large Magellanic Cloud (LMC). The cluster population in the LMC is characterised by ages spanning the range from ~10^6 to ~10^10 yr. The observations of the young and intermediate-age LMC clusters in our sample are sufficiently deep that we can detect binary systems based on a careful analysis of their CMDs: binary systems consisting of two stars of similar mass and temperature will have the same colour, but twice the luminosity of a single star. Thus, binary systems will appear as a broadening or a secondary main sequence in star cluster CMDs. Using our existing observations of carefully selected star clusters in the LMC, our group is involved in (i) estimating the binary fractions in each of our sample clusters, both overall and as a function of radius, using sophisticated Monte Carlo simulation techniques; (ii) connecting the expected radial dependence of the binary fraction to the effects of dynamical evolution and to the cluster stellar density, and we will thus (iii) constrain the importance of primordial versus dynamical production of binary systems; and (iv) obtain valuable constraints on the dynamical evolution of binary systems in these star clusters, by virtue of the clusters' age range. - Massive stellar evolution: How inidividual massive stars evolve as a function of metallicity, and how this in turn feeds back to the ISM. Do stars behave differently in MW, LMC and SMC clusters ? The IMF of massive stars and blue-red supergiant ratio as a function of metallicity. - Stellar winds from massive stars: their energy input to the ISM and effects on chemical evolution of galaxuies - Fundamental parameters of OB-stars and accurate calculations of theoretical spectra for input into e.g. STARBURST99. - Probing the chemical homogeneity of the Local Group by determining abundances of massive blue stars Potential PhD thesis or postdoc projects: - Star cluster formation in the intense environments of interacting and starburst galaxies - Star formation modes in gravitationally disturbed galaxy environments - The evolution and dynamical importance of binary systems in compact star clusters - Spectroscopic determinations of the initial mass function in young massive star clusters - The LMC star cluster systems as an evolutionary benchmark - Massive stellar evolution: How inidividual massive stars evolve as a function of metallicity, and how this in turn feeds back to the ISM. - Stellar winds from massive stars: their energy input to the ISM and effects on chemical evolution of galaxuies - Fundamental parameters of OB-stars and accurate calculations of theoretical spectra for input into e.g. STARBURST99. - Probing the chemical homogeneity of the Local Group by determining abundances of massive blue stars - on the topic of hot stars in starbursts (with Crowther) - on the topic of compact objects in dense environments (with Dhillon) Ongoing collaborations within the proposed network: - de Grijs: * de Grijs, Fritze-v. Alvensleben (Goettingen) - stellar populations, star cluster formation and evolution, interacting and starburst galaxies, theoretical population synthesis, multiple populations in old cluster systems * de Grijs, Gilmore - structure and evolution of resolved stellar clusters in the Magellanic Clouds, mass segregation, binary stars in clusters, dynamical cluster evolution * de Grijs, Smith - spectroscopy of young, massive stellar clusters in interacting and starburst galaxies, measuring the initial mass function in extreme cluster-forming environments * de Grijs, Lamers (Utrecht) - cluster disruption processes, tidal and gravitational effects on the cluster populations as a function of environment - Other collaborators: no information received * Smartt, Gilmore - ?? Date: Mon, 7 Apr 2003 23:31:20 +0100 (BST) From: Linda Smith To: Richard de Grijs Subject: Re: RTN information Hi Richard Sorry this is a bit late - blame the time difference and the snow storm in Madison. Jay and I will send you something on NGC 1140 tomorrow. Linda *********** name: Linda surname: Smith alias: LJS node: 2 email: ljs@star.ucl.ac.uk keywords: Massive stars, young massive clusters, interactions of winds and supernovae with ISM, feedback processes, evolutionary synthesis models, massive star populations in starburst galaxies. WR: synthesis, profile fitting, atmospheres updated. Collaborations within node: R. de Grijs (young massive clusters in starburst galaxies). Collaborations within network: I have no current formal collaborations with network members but have collaborated with some members in the past. There are overlaps in my research interests with most of the network members and I know the majority of them extremely well. I would therefore envisage that the proposed network will allow me to start new collaborations with European colleagues. (Isn't this one of the main purposes?) ************* Cathie Clarke: Ian Bonnell: Self consistent models of stellar clusters through accretion (no RT), plus feedback through winds. -------------------------------------------------------------------------------------- From: Richard de Grijs Sender: grijs@ast.cam.ac.uk To: Roberto Terlevich Subject: Basic information Dear Roberto, Here is additional info from Paul Crowther (will be in Sheffield as well, and therefore part of my node). Richard ---------- Forwarded message ---------- Date: Mon, 14 Apr 2003 14:48:02 +0100 (BST) From: Paul Crowther To: Richard de Grijs Subject: Basic information.. name: Paul surname: Crowther alias: PAC node: 2 email: pac@star.ucl.ac.uk -> Paul.Crowther@sheffield.ac.uk from 1/7/03 keywords: Stellar evolution, stellar populations collaborators: Linda Smith (UCL), Stephen Smartt (Cambridge), Daniel Schaerer (Geneva) Domain of expertise: --------------------- - Stellar modelling * stellar atmospheres and radiation transfer: atmosphere models for WR and OB stars, including stellar winds, non-LTE effects, and line blanketing - Stellar populations * Photoionization modelling of HII regions using newly developed evolutionary synthesis models. Chemical and energy yields * Resolved massive star populations in Local Group and beyond. * Near to mid-IR studies of young clusters Ongoing collaborations within the proposed network: --------------------------------------------------- LJS (UCL), PAC - Feedback from young clusters and starbursts PAC, SJS (Cambrige) - Massive stellar content of Local Group galaxies PAC, DS (Geneva) - Spectral synthesis of Wolf-Rayet galaxies Proposed topics for research and formation ------------------------------------------ - Formation and early evolution of clusters - Stellar content of young clusters - Stellar population studies of nearby to high redshift starbursts -------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------- Date: Fri, 21 Mar 2003 18:00:03 +0000 (GMT) From: Richard de Grijs Sender: grijs@ast.cam.ac.uk To: "Roberto J. Terlevich" Dear Roberto, Sorry for letting this slip, but below is the information you asked for for our node. I should stress that I think that if we have to choose between a postdoc or a PhD student, we should go for a postdoc (compared to Cambridge, PhD training is obviously less organised simply because of the smaller scale of the group). I hope this is all you need, if not let me know. Richard ----------------------------------------- Node: University of Sheffield, UK PI: Richard de Grijs possible participants (I should ask them!): Paul Crowther, Vik Dhillon Note that Sheffield is located in South Yorkshire, which has been designated a "less-favoured region" by the EU. This means that including Sheffield as a node, the chances of getting funding will be increased, everything else being equal. Expertise: The expertise offered at the University of Sheffield in the field of star clusters and their evolution is essentially two-fold: (1) Star cluster formation in the intense environments of interacting and starburst galaxies. Star cluster formation seems to be a (if not the) major mode of star formation in the extreme environments found in interacting and starburst galaxies. As such, they trace the major stages of galaxy formation and evolution. The main objective of our research at Sheffield is to use the young and intermediate-age star clusters as tracers of galaxy evolution and to determine whether they have the potential to evolve into old Galactic globular cluster-type objects by the time they reach similar ages. If so, this implies that globular cluster formation did not only happen at the time of galaxy fornation, but continues until the present. If we can establish this scenario beyond a doubt, this will have far-reaching consequences for theories of galaxy formation and evolution. These questions can most easily be addressed using the star cluster luminosity (or mass) functions in conjunction with models for the evolution of star cluster SYSTEMS. Alternatively, we are engaged in a number of projects in which we try to determine the stellar initial mass function (IMF) based on high-resolution spectroscopy (HST/STIS, VLT/UVES). The slope of the IMF is the most crucial ingredient for the evolution and survivability of an individual cluster Specific expertise offered at Sheffield is predominantly of observational and interpretational nature. We have developed techniques to use multi-passband imaging observations (mainly taken with the high resolution offered by the Hubble Space Telescope, but applicable to ground-based efforts as well) to simultaneously determine ages, masses, metallicities and indeed extinction values for individual star clusters. These techniques have been applied successfully to a number of interacting and starburst galaxies, including M82, NGC 3310, M51, NGC 6745, NGC 1569, among others. High-resolution spectroscopy is used to determine dynamical cluster masses, and in combination with HST imaging, their mass-to-light ratios, which are then compared to models using a variety of prescriptions for the evolution of single stellar populations with certain IMF parameters. (2) The internal dynamics of star clusters Rich, compact star clusters are the ideal laboratories for the study of stellar evolution. As such, the old globular clusters (GCs) in the Milky Way have been used extensively for this purpose, and their colour-magnitude diagrams (CMDs) are now well understood. However, the evolution of the dynamically important binary population is not yet well understood. Although the Milky Way contains a large population of GCs, they are predominantly old, with ages largely in excess of 10 Gyr. Therefore, we cannot use the Galactic GC population to follow the evolution of binary systems in the dense environments of GC-type objects. Fortunately, however, we have access to a unique data set of deep HST observations of a carefully selected sample of similar star clusters in the Large Magellanic Cloud (LMC). The cluster population in the LMC is characterised by ages spanning the range from ~10^6 to ~10^10 yr. The observations of the young and intermediate-age LMC clusters in our sample are sufficiently deep that we can detect binary systems based on a careful analysis of their CMDs: binary systems consisting of two stars of similar mass and temperature will have the same colour, but twice the luminosity of a single star. Thus, binary systems will appear as a broadening or a secondary main sequence in star cluster CMDs. Using our existing observations of carefully selected star clusters in the LMC, our group is involved in (i) estimating the binary fractions in each of our sample clusters, both overall and as a function of radius, using sophisticated Monte Carlo simulation techniques; (ii) connecting the expected radial dependence of the binary fraction to the effects of dynamical evolution and to the cluster stellar density, and we will thus (iii) constrain the importance of primordial versus dynamical production of binary systems; and (iv) obtain valuable constraints on the dynamical evolution of binary systems in these star clusters, by virtue of the clusters' age range. a List of ongoing collaborations with other participants in this RTN: - Uta Fritze-v. Alvensleben (we jointly supervise 2 PhD students, who are based at Goettingen; we are both co-PI's on a grant from the German Research Council) - Gerry Gilmore (projects related to the LMC cluster sample; mass segregation issues, dynamical cluster evolution) b The Sheffield astronomy group is small (5 permanent staff in astronomy, within a large physics department). Opportunities to do a PhD are numerous, however, in particular because the group has just been expanded from 3 to 5 staff members, so that there is a lot of science going on. Related to the topic of this RTN, PhD theses can be done with myself: e.g., - Star cluster formation in the intense environments of interacting and starburst galaxies - Star formation modes in gravitationally disturbed galaxy environments - The evolution and dynamical importance of binary systems in compact star clusters - Spectroscopic determinations of the initial mass function in young massive star clusters - The LMC star cluster systems as an evolutionary benchmark - ... etc. ... with Paul Crowther - on the topic of hot stars in starbursts with Vik Dhillon - on the topic of compact objects in dense environments There is an active seminar schedule, and close interaction with neighbouring universities (Leicester, Nottingham, Leeds) c See my research paragraphs above. In the field of age dating star clusters and their use as tracers of galaxy evolution, as well as the evolution of the cluster luminosity and mass function, we are at the forefront of current astrophysics, as shown by numerous recent articles. Similarly, in the field of the evolution of hot stars as such (Paul Crowther's group), our research activities are also up to date.