2,011 research outputs found
Progress on the hybridization of cultivated lentil Lens culinaris Medik. and wild species Lens tomentosus Ladizinsky
Non-Peer ReviewedThe domestication of lentil has produced bottleneck effects resulting in a narrow genetic basis which has resulted in reduced levels of resistance to biotic and abiotic stresses relative to its wild relatives. Phenotypic variability studies have identified wild lentil germplasm with resistance to anthracnose (Colletotrichum spp.), ascochyta blight (Ascochyta lentis), stemphylium blight (Stemphylium botryosum) and Orobanche spp. root-holoparasitic infection. To increase genetic diversity and resistance to biotic and abiotic stresses in new cultivars, introgression of desirable genes from crop wild relatives is necessary. Current evidences suggest seven taxa in the genus Lens Mill.: L. culinaris (ssp. culinaris and ssp. orientalis), L. odemensis, L. ervoides, L. nigricans, L. tomentosus and L. lamottei. Morphologically, the wild lentil species L. tomentosus most resembles L. orientalis although it can be distinguished as having a hairy pod. Previous attempts of crossing cultivated lentil L. culinaris with the wild species L. tomentosus, have failed to produce viable seeds, as with time growing embryos are gradually degraded and shrivelled, and non-viable seeds are formed; consequently an embryo rescue technique has been employed with limited success. However, this technique is time consuming, and also requires controlled growing environments and highly skilled technical personal. Using very comprehensive phenotyping technique, we have crossed cultivated lentil cultivar ‘Indian head’ with L. tomentosus and successfully produced viable F1 generation and it has currently being evaluated for phenological and morphological characteristics. Our results suggest successful results can be achieved by selecting phenotypically resembling lentil species as parents as an initial step
Chemical Abundances Of Open Clusters From High-Resolution Infrared Spectra. I. NGC 6940
We present near-infrared spectroscopic analysis of 12 red giant members of
the Galactic open cluster NGC 6940. High-resolution (R45000) and high
signal-to-noise ratio (S/N > 100) near-infrared H and K band spectra were
gathered with the Immersion Grating Infrared Spectrograph (IGRINS) on the 2.7m
Smith Telescope at McDonald Observatory. We obtained abundances of H-burning
(C, N, O), (Mg, Si, S, Ca), light odd-Z (Na, Al, P, K), Fe-group
(Sc, Ti, Cr, Fe, Co, Ni) and neutron-capture (Ce, Nd, Yb) elements. We report
the abundances of S, P, K, Ce, and Yb in NGC 6940 for the first time. Many OH
and CN features in the H band were used to obtain O and N abundances. C
abundances were measured from four different features: CO molecular lines in
the K band, high excitation C I lines present in both near-infrared and
optical, CH and bands in the optical region. We have also determined
ratios from the R-branch band heads of first overtone (2-0) and
(3-1) (2-0) lines near 23440
\overset{\lower.5em\circ}{\mathrm{A}} and (3-1) lines at about
23730 \overset{\lower.5em\circ}{\mathrm{A}}. We have also investigated the HF
feature at 23358.3 \overset{\lower.5em\circ}{\mathrm{A}}, finding solar
fluorine abundances without ruling out a slight enhancement. For some elements
(such as the group), IGRINS data yield more internally
self-consistent abundances. We also revisited the CMD of NGC 6940 by
determining the most probable cluster members using Gaia DR2. Finally, we
applied Victoria isochrones and MESA models in order to refine our estimates of
the evolutionary stages of our targets.Comment: 16 pages, 10 figure
Age Constraints for an M31 Globular Cluster from Main Sequence Photometry
We present a color-magnitude diagram (CMD) of the globular cluster SKHB-312
in the Andromeda galaxy (M31), obtained with the Advanced Camera for Surveys on
the Hubble Space Telescope. The cluster was included in deep observations taken
to measure the star formation history of the M31 halo. Overcoming a very
crowded field, our photometry of SKHB-312 reaches V ~ 30.5 mag, more than 1 mag
below the main sequence turnoff. These are the first observations to allow a
direct age estimate from the turnoff in an old M31 cluster. We analyze its CMD
and luminosity function using a finely-spaced grid of isochrones that have been
calibrated using observations of Galactic clusters taken with the same camera
and filters. The luminosity difference between the subgiant and horizontal
branches is ~0.2 mag smaller in SKHB-312 than in the Galactic clusters 47 Tuc
and NGC 5927, implying SKHB-312 is 2-3 Gyr younger. A quantitative comparison
to isochrones yields an age of 10 +2.5/-1 Gyr
Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies
‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15383.xWe investigate a class of rapidly growing emission line galaxies, known as 'Green Peas', first noted by volunteers in the Galaxy Zoo project because of their peculiar bright green colour and small size, unresolved in Sloan Digital Sky Survey imaging. Their appearance is due to very strong optical emission lines, namely [O iii]λ5007 Å, with an unusually large equivalent width of up to ∼1000 Å. We discuss a well-defined sample of 251 colour-selected objects, most of which are strongly star forming, although there are some active galactic nuclei interlopers including eight newly discovered narrow-line Seyfert 1 galaxies. The star-forming Peas are low-mass galaxies (M∼ 108.5–1010 M⊙) with high star formation rates (∼10 M⊙ yr−1) , low metallicities (log[O/H]+ 12 ∼ 8.7) and low reddening [ E(B−V) ≤ 0.25 ] and they reside in low-density environments. They have some of the highest specific star formation rates (up to ∼10−8 yr−1 ) seen in the local Universe, yielding doubling times for their stellar mass of hundreds of Myr. The few star-forming Peas with Hubble Space Telescope imaging appear to have several clumps of bright star-forming regions and low surface density features that may indicate recent or ongoing mergers. The Peas are similar in size, mass, luminosity and metallicity to luminous blue compact galaxies. They are also similar to high-redshift ultraviolet-luminous galaxies, e.g. Lyman-break galaxies and Lyα emitters, and therefore provide a local laboratory with which to study the extreme star formation processes that occur in high-redshift galaxies. Studying starbursting galaxies as a function of redshift is essential to understanding the build up of stellar mass in the Universe.Peer reviewe
Genetic study of Ascochyta blight resistance in chickpea and lentil
Non-Peer ReviewedAscochyta blight is responsible for severe crop losses in most chickpea and lentil production areas around the world. The research was conducted to study the genetic basis for Ascochyta blight resistance in chickpea and lentil by means of QTL analysis, and PCR-based approaches to identify resistance gene analogues (RGA) sequences in the lentil genome. An AFLP and three SSR markers were linked to the gene(s) for Ascochyta resistance in a chickpea population derived from a cross between CDC Chico and CDC Marengo. Two QTL that explained 36 % and 29 % of the disease reaction variability were identified in a lentil RI population derived from a cross between ILL5588 and L692-16-1. These markers were converted into SCAR markers to simplify their use for marker-assisted selection
VLBI observations of the Crab nebula pulsar
Observations were made at meter wave-lengths using very long base-line interferometry techniques. At 196.5 MHz no resolution of the pulsar are observed; all the pulse shapes observed with the interferometers are similar to single dish profiles, and all the power pulsates. At 111.5 MHz besides the pulsing power there is always a steady component, presumably due to interstellar scattering. The pulsar is slightly resolved at 111.5 MHz with an apparent angular diameter of 0.07 sec ? 0.01 sec. A 50 percent linear polarization of the time-averaged power is noted at 196.5 MHz; at 111.5 MHz, 20 percent of the total time-averaged power is polarized, 35 percent of the pulsing power is polarized, and the steady component is unpolarized
The WFC3 Galactic Bulge Treasury Program: A First Look at Resolved Stellar Population Tools
[Abridged] When WFC3 is installed on HST, the community will have powerful
new tools for investigating resolved stellar populations. The WFC3 Galactic
Bulge Treasury program will obtain deep imaging on 4 low-extinction fields.
These non-proprietary data will enable a variety of science investigations not
possible with previous data sets. To aid in planning for the use of these data
and for future proposals, we provide an introduction to the program, its
photometric system, and the associated calibration effort.
The observing strategy is based upon a new 5-band photometric system spanning
the UV, optical, and near-infrared. With these broad bands, one can construct
reddening-free indices of Teff and [Fe/H]. Besides the 4 bulge fields, the
program will target 6 fields in well-studied star clusters, spanning a wide
range of [Fe/H]. The cluster data serve to calibrate the indices, provide
population templates, and correct the transformation of isochrones into the
WFC3 photometric system. The bulge data will shed light on the bulge formation
history, and will also serve as population templates for other studies. One of
the fields includes 12 candidate hosts of extrasolar planets.
CMDs are the most popular tool for analyzing resolved stellar populations.
However, due to degeneracies among Teff, [Fe/H], and reddening in traditional
CMDs, it can be difficult to draw robust conclusions from the data. The 5-band
system used for the bulge Treasury observations will provide indices that are
roughly orthogonal in Teff and [Fe/H], and we argue that model fitting in an
index-index diagram will make better use of the information than fitting
separate CMDs. We provide simulations to show the expected data quality and the
potential for differentiating between different star-formation histories.Comment: Accepted for publication in The Astronomical Journal. 9 pages, 8
figures, latex, AJ forma
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