The ACS LCID Project: overview and first results

The star formation history (SFH) of Local Group galaxies is a powerful tool for studying their evolution, including chemical enrichment histories and stellar population gradients, which in turn may shed light on the role of reionization or Supernovae feedback in galaxy formation and evolution. In particular, isolated dwarfs are ideal laboratories since their evolution has not been complicated by the vicinity of giant galaxies. In this paper, we present the project Local Cosmology from Isolated Dwarfs (LCID), aimed at deriving detailed SFHs for a sample of Local Group isolated dwarf galaxies. To accomplish this goal we have collected, using the ACS on board the HST, color-magnitude diagrams (CMD) reaching their oldest main sequence turnoff (V~28 or M_V~+3.5) with good photometric accuracy. Some preliminary results from the CMDs are shown and briefly discussed.Comment: 4 pages, 2 figures. To appear in the Proceedings of IAU Symposium 241: "Stellar Populations as Building Blocks of Galaxies", 10-16 December, 2006 at La Palma, Canary Islands, Spai

The Political and Economic Context of European defence R&D

Along with all other defence-related issues, defence research is a controversial area for EU action. Until recently, defence issues have not figured prominently among EU policy discussions and defence research has played little, if any, role in European technology policy. Although the Framework Programme is funding research projects that could have potential military applications in addition to their explicit civilian goals, there is no strategy on how to address such "dual-use" research activities. Yet, this paper argues that the interaction between technologies developed for civilian and for military use has led to a situation in which it is increasingly difficult to refer to distinct military and civilian technology bases. From the point of view of policy formulation a strict separation between defence and civilian technologies is increasingly appearing as anachronistic. The extent to which "dual-use" research will be explicitly considered in the development of the 6th Framework Programme will again emerge as a matter of debate. The paper presents and discusses different avenues through which dual-use and defence-related research could be given formal consideration in the development and implementation of the 6th Framework Programme.EU research policy, defence, "dual-use" research

The Stellar Content and the Star Formation History of the Local Group Dwarf Galaxy LGS 3

The star formation history (SFH) and the properties of the dwarf galaxy LGS3 are analyzed using color-magnitude (CM) diagrams plotted from VRI photometry of 736 stars. The distance to the galaxy is estimated through the position of the tip or the red giant branch. Two acceptable results have been obtained: 0.77+/-0.07 Mpc and 0.96+/-0.07 Mpc, although the first value is favored by complementary considerations on the stellar content of the galaxy. Both values make LGS3 a possible satellite of M31 or of M33. The SFH is investigated for each of the two adopted distances comparing the observed CM diagrams with model CM diagrams computed for different star formation rates (psi(t)) and chemical enrichment laws (Z(t)). The results are compatible with LGS3 having been forming stars since an early epoch, 15-12 Gyr ago, at an almost constant rate if distance is 0.77 Mpc or at an exponentially decreasing rate if distance is 0.96 Mpc. According to our models, the current metallicity would range from Z~0.0007 to Z~0.002. Other results are the current psi(t): (0.55+/-0.04)x10^(-10) Mo yr^(-1) pc^(-2) or (0.47+/-0.07)x10^(-10) Mo yr^(-1) pc^(-2), depending of the distance, and its average for the entire life of the galaxy, =(1.4+/-0.1)x10^(-10) Mo yr^(-1) pc^(-2). At the present psi(t), the probability of LGS3 having an HII region is 0.2, which is compatible with the fact that no HII regions have been found in the galaxy. Its fraction of gas relative to the mass intervening in the chemical evolution is about 0.40 and its percentage of dark matter (that which cannot be explained as stellar remnants or by extrapolation of the used IMF to low masses) is 95%. The results for psi(t) and Z(t) for d=0.77 Mpc are compatible with a moderate outflow of well mixed material (lambda=3), but largeComment: 23 pages, 3 tables, 14 figures. AJ in pres

Computational coverage of type logical grammar: The Montague test

It is nearly half a century since Montague made his contributions to the field of logical semantics. In this time, computational linguistics has taken an almost entirely statistical turn and mainstream linguistics has adopted an almost entirely non-formal methodology. But in a minority approach reaching back before the linguistic revolution, and to the origins of computing, type logical grammar (TLG) has continued championing the flags of symbolic computation and logical rigor in discrete grammar. In this paper, we aim to concretise a measure of progress for computational grammar in the form of the Montague Test. This is the challenge of providing a computational cover grammar of the Montague fragment. We formulate this Montague Test and show how the challenge is met by the type logical parser/theorem-prover CatLog2.Peer ReviewedPostprint (published version

The stellar content of the Local Group dwarf galaxy Phoenix

We present new deep $VI$ ground-based photometry of the Local Group dwarf galaxy Phoenix. Our results confirm that this galaxy is mainly dominated by red stars, with some blue plume stars indicating recent (100 Myr old) star formation in the central part of the galaxy. We have performed an analysis of the structural parameters of Phoenix based on an ESO/SRC scanned plate, in order to search for differentiated component. The results were then used to obtain the color-magnitude diagrams for three different regions of Phoenix in order to study the variation of the properties of its stellar population. The young population located in the central component of Phoenix shows a clear asymmetry in its distribution, that could indicate a propagation of star formation across the central component. The HI cloud found at 6 arcmin Southwest by Young & Lo (1997) could have been involved in this process. We also find the presence of a substantial intermediate-age population in the central region of Phoenix that would be less abundant or absent in its outer regions. This result is also consistent with the gradient found in the number of horizontal branch stars, whose frequency relative to red giant branch stars increases towards the outer part of the galaxy. These results, together with those of our morphological study, suggest the existence of an old, metal-poor population with a spheroidal distribution surrounding the younger inner component of Phoenix. This two-component structure may resemble the halo-disk structure observed in spirals, although more data, in particular on kinematics, are necessary to confirm this.Comment: 46 pages, 21 figures, 9 Tables, to be published in AJ, August 9

A reply to Kubota and Levine on gapping

In a series of papers Kubota and Levine give an account of gapping and determiner gapping in terms of hybrid type logical grammar, including anomalous scopal interactions with auxiliaries and negative quantifiers. We make three observations: i) under the counterpart assumptions that Kubota and Levine make, the existent displacement type logical grammar account of gapping already accounts for the scopal interactions, ii) Kubota and Levine overgenerate determiner-verb order permutations in determiner gapping conjuncts whereas the immediate adaptation of their proposal to displacement type logical grammar does not do so, and iii) Kubota and Levine do not capture simplex gapping as a special case of complex gapping, but require distinct lexical entries for the two cases; we show how a generalisation of displacement type logical grammar allows both simplex and discontinuous gapping under a single type assignmentPostprint (author's final draft

Model color-magnitude diagrams for Hubble Space Telescope observations of Local Group dwarf galaxies

In this paper, we discuss a method to conduct a quantitative study of the star formation history (SFH) of Local Group (LG) galaxies using (HST) data. This method has proven to be successful in the analysis of the SFH of the same kind of galaxies using ground-based observations. It is based on the comparison of observed CMDs with a set of model CMDs. The latter are computed assuming different evolutionary scenarios, and include a detailed simulation of observational effects. HST CMDs are ~3 mags deeper than typical ground-based CMDs, allowing the observation, for all LG galaxies, of a part of the CMD that up till now had remained accessible only for the very nearest galaxies. A very important feature that will become accessible is the HB+red-clump. The distribution of stars along this structure is quite sensitive to age and metallicity and should provide a very important improvement in the time resolution of the SFH for stars older than ~2-3 Gyr. We show and discuss four model CMDs which would be comparable with CMDs from deep HST observations. These model CMDs represent the following evolutionary scenarios corresponding to a wide range of dwarf galaxy sub-types from dI to dE: A) a constant SFR from 15Gyr ago to the present time; B) as A), but with the SFR stopped 0.5 Gyr ago; C) a constant SFR in the age range 10-9Gyr and D) as C) but in the age range 15-12 Gyr. In all four cases a range of metallicity from Z=0.0001 to Z=0.004 has been assumed. The present analysis is just a first qualitative approach to what one may expect to find in the CMDs of LG galaxies. However a complete set of model CMDs must be computed to analize the data for each galaxy, using the crowding effects derived for that particular galaxy.Comment: 2 fi