Late Planting Decisions with Crop Insurance: Decision Guidelines for Michigan Farmers in Spring 2011

Michigan has had unusually wet planting conditions in 2011, leading to substantial acreage that has not been planted at this late date. Farmers who purchased crop insurance have many options available to them. This paper addresses the major crop insurance decisions that farmers will face during the next 30 days.crop insurance, prevented planting, risk management, farm management, corn returns, soybean returns, Agricultural and Food Policy, Crop Production/Industries, Farm Management, Risk and Uncertainty,

The globular cluster system of NGC 1316 IV. Nature of the star cluster complex SH2

The light of the merger remnant NGC 1316 is dominated by old and intermediate-age stars. The only sign of current star formation in this big galaxy is the HII region SH2, an isolated star cluster complex with a ring-like morphology and an estimated age of 0.1 Gyr at a galactocentric distance of about 35 kpc. A nearby intermediate-age globular cluster, surrounded by weak line emission and a few more young star clusters, is kinematically associated. The origin of this complex is enigmatic. The nebular emission lines permit a metallicity determination which can discriminate between a dwarf galaxy or other possible precursors. We used the Integrated Field Unit of the VIMOS instrument at the Very Large Telescope of the European Southern Observatory to study the morphology, kinematics, and metallicity employing line maps, velocity maps, and line diagnostics of a few characteristic spectra. The line ratios of different spectra vary, indicating highly structured HII regions, but define a locus of uniform metallicity. The strong-line diagnostic diagrams and empirical calibrations point to a nearly solar or even super-solar oxygen abundance. The velocity dispersion of the gas is highest in the region offset from the bright clusters. Star formation may be active on a low level. There is evidence for a large-scale disk-like structure in the region of SH2, which would make the similar radial velocity of the nearby globular cluster easier to understand. The high metallicity does not fit to a dwarf galaxy as progenitor. We favour the scenario of a free-floating gaseous complex having its origin in the merger 2 Gyr ago. Over a long period the densities increased secularly until finally the threshold for star formation was reached. SH2 illustrates how massive star clusters can form outside starbursts and without a considerable field population.Comment: 10 pages, 5 figures, accepted for Astronomy & Astrophysic

The globular cluster system of NGC1316: III. Kinematic complexity

Defining photometric peculiar type Ia Supernovae The merger remnant NGC 1316 (Fornax A) is one of the most important objects regarding the investigation of and thus an important object to study merger-related processes. A recent photometric study used globular clusters in NGC 1316 to constrain its star formation history, but without the knowledge of individual radial velocities. The kinematical properties of the globular cluster system in comparison with the diffuse stellar light might reveal more insight into the formation of NGC 1316. Of particular interest is the dark matter content. Planetary nebulae in NGC 1316 indicate a massive dark halo, and globular cluster velocities provide independent evidence. We aim at measuring radial velocities of globular clusters in NGC 1316. We use these kinematical data to investigate the global structure of NGC 1316 and to constrain the dark matter content. We perform multi-object-spectroscopy with VLT/FORS2 and MXU. Out of 562 slits, we extract radial velocities for 177 globular clusters. Moreover, we measure radial velocities of the integrated galaxy light, using slits with a sufficiently bright ”sky”. To these data, we add 20 cluster velocities from Goudfrooij et al. 2001b. In an appendix, we identify new morphological features of NGC 1316 and its companion galaxy NGC 1317. The GC sample based on radial velocities confirms the colour peaks already found in our photometric study. The bright clusters, which probably have their origin in a 2 Gyr-old starburst and younger star formation events, avoid the systemic velocity. A Gaussian velocity distribution is found only for clusters fainter than about mR = 22 mag. The velocity distribution of clusters shows a pronounced peak at 1600 km/s. These clusters populate a wide area in the south-western region which we suspect to be a disk population. Globular clusters or subsamples of them do not show a clear rotation signal. This is different from the galaxy light, where rotation along the major axis is discernable out to 3 0 radius. The kinematic major axis of NGC 1316 is misaligned by about 10◦ with the photometric major axis, which might indicate a triaxial symmetry. A simple spherical model like that suggested by dynamical analyses of planetary nebulae reproduces also the velocity dispersions of the faint globular clusters. The central dark matter density of the present model resembles a giant elliptical galaxy. This contradicts population properties which indicate spiral galaxies as pre-merger components. MOND would provide a solution, but the kinematical complexity of NGC 1316 does not allow a really firm conclusion. However, NGC 1316 might anyway be a problem for a CDM scenario, if the high dark matter density in the inner region is confirmed in future studies.Fil: Richtler, T.. Universidad de Concepción; ChileFil: Hilker, M.. European Southern Observatory; AlemaniaFil: Kumar, B.. Aryabhatta Research Institute Of Observational Sciences; IndiaFil: Bassino, Lilia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Astrofísica de la Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Gomez, M.. Universidad Andres Bello; ChileFil: Dirsch, B.. Friedrich-Ebert Gymnasium; Alemani

The Globular Cluster System of NGC 1399 IV. Some noteworthy objects

We present 8 bright globular clusters and/or objects of less familiar nature which we found in the course of scrutinizing the globular cluster system of NGC 1399. These objects are morphologically striking, either by their sizes or by other structural properties. Some of them may be candidates for stripped dwarf galaxy nuclei, emphasizing the possible role of accretion in the NGC 1399 cluster system. They are all highly interesting targets for further deep spectroscopy or HST-imaging. Since these objects have been found within an area of only 42 arcmin**2, we expect many more still to be detected in a full census of the NGC 1399 cluster system.Comment: 6 pages, 3 figures, accepted by A&A (Research Note

The dark matter halo of NGC 1399 - CDM or MOND?

Context: Central galaxies in galaxy clusters may be key discriminants in the competition between the cold dark matter (CDM) paradigm and modified Newtonian dynamics (MOND). Aims: We investigate the dark halo of NGC 1399, the central galaxy of the Fornax cluster, out to a galactocentric distance of 80 kpc. Methods: The data base consists of 656 radial velocities of globular clusters obtained with MXU/VLT and GMOS/Gemini, which is the largest sample so far for any galaxy. We performed a Jeans analysis for a non-rotating isotropic model. Results: An NFW halo with the parameters rs = 50 kpc and gs = 0.0065 M⊙/pc3 provides a good description of our data, fitting well to the X-ray mass. More massive halos are also permitted that agree with the mass of the Fornax cluster as derived from galaxy velocities. We compare this halo with the expected MOND models under isotropy and find that additional dark matter on the order of the stellar mass is needed to get agreement. A fully radial infinite globular cluster system would be needed to change this conclusion. Conclusions: Regarding CDM, we cannot draw firm conclusions. To really constrain a cluster wide halo, more data covering a larger radius are necessary. The MOND result appears as a small-scale variant of the finding that MOND in galaxy clusters still needs dark matter.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Searches for Ultra-Compact Dwarf Galaxies in Galaxy Groups

We present the results of a search for ultra-compact dwarf galaxies (UCDs) in six different galaxy groups: Dorado, NGC1400, NGC0681, NGC4038, NGC4697 and NGC5084. We searched in the apparent magnitude range 17.5 < b_j < 20.5 (except NGC5084: 19.2 < b_j < 21.0). We found 1 definite plus 2 possible UCD candidates in the Dorado group and 2 possible UCD candidates in the NGC1400 group. No UCDs were found in the other groups. We compared these results with predicted luminosities of UCDs in the groups according to the hypothesis that UCDs are globular clusters formed in galaxies. The theoretical predictions broadly agree with the observational results, but deeper surveys are needed to fully test the predictions.Comment: 8 pages, 2 figures, accepted for publication in MNRA

The globular cluster system of NGC 1399 V. dynamics of the cluster system out to 80 kpc

(Abridged) We use the largest set of globular cluster velocities obtained so far of any elliptical galaxy to revise and extend the previous investigations of the dynamics of NGC 1399, the central dominant galaxy of the nearby Fornax cluster of galaxies. Our sample now comprises velocities for almost 700 GCs with projected galactocentric radii between 6 and 100 kpc. In addition, we use velocities published by Bergond et al. (2007). We study the kinematics of the metal-poor and metal-rich subpopulations and perform spherical Jeans modelling. The most important results are: The metal-rich (red) GCs resemble the stellar field population of NGC 1399 in the region of overlap. Both subpopulations are kinematically distinct and do not show a smooth transition. It is not possible to find a common dark halo which reproduces simultaneously the properties of both subpopulations. Some velocities of blue GCs are only to be explained by orbits with very large apogalactic distances, thus indicating a contamination with GCs which belong to the entire Fornax cluster rather than to NGC 1399. Stripped GCs from nearby elliptical galaxies, particularly NGC 1404, may also contaminate the metal-poor sample. We argue in favour of a scenario in which the majority of the blue cluster population has been accreted during the assembly of the Fornax cluster. The red cluster population shares the dynamical history of the galaxy itself. Therefore we recommend to use a dark halo based on the red GCs alone. The dark halo which fits best is marginally less massive than the halo quoted by Richtler et al. (2004). The comparison with X-ray analyses is satisfactory in the inner regions, but without showing evidence for a transition from a galaxy to a cluster halo, as suggested by X-ray work.Comment: 31 pages, accepted for publication in A&A. Online material will be available from the CD