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Cousins Photometry and Temperatures for the Hyades, Coma, NGC 752, Praesepe, and M67
In this paper, new Cousins VRI data are presented for NGC 752 and Praesepe, and new and extant data are combined into an augmented database for M67. For those three clusters, catalogs containing Cousins VRI photometry, reddening-corrected values of (V -K)(J), and temperatures are produced. The same is done for Coma by using both previously published and newly derived Cousins photometry. An extant set of catalogs for the Hyades is updated to include V magnitudes and values of (R -I)(C) that were published after the original catalogs appeared. Finally, M67 V magnitudes published previously by Sandquist are corrected for an effect that depends on location on the face of the cluster. The corrected data and values of (V -I)(C) given by Sandquist are then set out in a supplementary catalog. Data files containing all of these catalogs are deposited in the CDS archives. To assess the quality of the data in the catalogs, the consistency of extant Cousins VRI databases is tested by performing analyses with the following features: (1) quantities as small as a few millimags are regarded as meaningful; (2) statistical analysis is applied; (3) no use is made of data other than VRI measurements and comparable results; (4) no inferences are drawn from color-magnitude comparisons; (5) pertinent data that have not been included previously are analyzed; and (6) results based on direct comparisons of stellar groups at the telescope are featured. In this way, it is found that our updated M67 color data and those of Sandquist are on the E region zero point. In contrast, values of (V -I)(C) from Montgomery and collaborators are found to be too red by 27 +/- 3 mmag, with an even larger offset being likely for unpublished data from Richer and his collaborators. Zero-point tests of our Cousins VRI colors for Coma, Praesepe, and NGC 752 are also satisfactory. Scale factor tests of the M67 colors are performed, and a likely scale factor error in the Montgomery et al. colors is found. However, it appears at present that the scale factors of our M67 colors and those of Sandquist are satisfactory. For the most part, zero-point tests of the assembled V magnitudes are also satisfactory, although it is found that further work on the V magnitudes for Praesepe and M67 would be useful. To put these results in perspective, it is pointed out that photometric tests that are satisfactory at the few-millimag level have been published for some two decades and so are not appearing for the first time in this paper.Astronom
The enigmatic young object : Walker 90/V590 Monocerotis
Aims. We assess the evolutionary status of the intriguing object Walker 90/V590 Mon, which is located about 20 arcmin northwest of the Cone Nebula near the center of the open cluster NGC 2264. This object, according to its most recent optical spectral type determination (B7), which we confirmed, is at least 3 mag too faint in V for the cluster distance, but it shows the classical signs of a young pre-main sequence object, such as highly variable H emission, Mg II emission, IR excess, UV continuum, and optical variability.
Methods. We analyzed a collection of archival and original data on Walker 90, covering 45 years including photometry, imaging, and spectroscopic data ranging from ultraviolet to near-infrared wavelengths.
Results. According to star formation processes, it is expected that, as this object clears its primordial surroundings, it should become optically brighter, show a weakening of its IR excess and present decreasing line emissions. This behavior is supported by our observations and analysis, but timescales are expected to be longer than the one observed here. Based on photometric data secured in 2007, we find Walker 90 at its brightest recorded optical magnitude √(12.47 ± 0.06). We document an evolution in spectral type over the past five decades (from A2/A3 to currently B7 and as early as B4), along with a decrease in the near-infrared K fluxes. From near-infrared VISIR images secured in 2004, Walker 90 appears as a point source placing an upper limit of < 0.1" for its diameter. Evidence of turbulent inflows is found in rapidly changing inverse P-Cygni profiles in the lower Balmer lines, with a broadening of ±400 km s-1 in Hα and a redshifted component in Hβ with a terminal velocity of ~600 km s-1. The measured steep UV continuum fluxes (mimicking a star as early as B4), added to a tentative identification of N V emission, suggest a strong non-photospheric component, typically of fluxes arising from a thermally inhomogeneous accretion disk. We detect a well defined 2200 Å bump, indicative of dense material in the line-of-sight. We conclude that many observational features are explained if W90 is a flared disk system, surrounded by an inclined optically thick accretion disk
A new LMC K-band distance from precision measurements of nearby red clump stars
High-precision (sigma < 0.01) new JHK observations of 226 of the brightest
and nearest red clump stars in the solar neighbourhood are used to determine
distance moduli for the LMC. The resulting K- and H-band values of 18.47\pm0.02
and 18.49\pm0.06 imply that any correction to the K-band Cepheid PL relation
due to metallicity differences between Cepheids in the LMC and in the solar
neighborhood must be quite small.Comment: 7 pages, 4 figure
The EBLM project. II. A very hot, low-mass M dwarf in an eccentric and long period eclipsing binary system from SuperWASP
In this paper, we derive the fundamental properties of
1SWASPJ011351.29+314909.7 (J0113+31), a metal-poor (-0.40 +/- 0.04 dex),
eclipsing binary in an eccentric orbit (~0.3) with an orbital period of ~14.277
d. Eclipsing M dwarfs orbiting solar-type stars (EBLMs), like J0113+31, have
been identified from WASP light curves and follow-up spectroscopy in the course
of the transiting planet search. We present the first binary of the EBLM sample
to be fully analysed, and thus, define here the methodology. The primary
component with a mass of 0.945 +/- 0.045 Msun has a large radius (1.378 +/-
0.058 Rsun) indicating that the system is quite old, ~9.5 Gyr. The M-dwarf
secondary mass of 0.186 +/- 0.010 Msun and radius of 0.209 +/- 0.011 Rsun are
fully consistent with stellar evolutionary models. However, from the
near-infrared secondary eclipse light curve, the M dwarf is found to have an
effective temperature of 3922 +/- 42 K, which is ~600 K hotter than predicted
by theoretical models. We discuss different scenarios to explain this
temperature discrepancy. The case of J0113+31 for which we can measure mass,
radius, temperature and metallicity, highlights the importance of deriving
mass, radius and temperature as a function of metallicity for M dwarfs to
better understand the lowest mass stars. The EBLM Project will define the
relationship between mass, radius, temperature and metallicity for M dwarfs
providing important empirical constraints at the bottom of the main sequence.Comment: 13 pages, 7 figures. Accepted for publication in A&
Inoculations with Arbuscular Mycorrhizal Fungi Increase Vegetable Yields and Decrease Phoxim Concentrations in Carrot and Green Onion and Their Soils
Background As one of the most widely used organophosphate insecticides in vegetable production, phoxim (C12H15N2O3PS) is often found as residues in crops and soils and thus poses a potential threat to public health and environment. Arbuscular mycorrhizal (AM) fungi may make a contribution to the decrease of organophosphate residues in crops and/or the degradation in soils, but such effects remain unknown. Methodology/Principal Findings A greenhouse pot experiment studied the influence of AM fungi and phoxim application on the growth of carrot and green onion, and phoxim concentrations in the two vegetables and their soil media. Treatments included three AM fungal inoculations with Glomus intraradices BEG 141, G. mosseae BEG 167, and a nonmycorrhizal control, and four phoxim application rates (0, 200, 400, 800 mg l−1, while 400 mg l−1 rate is the recommended dose in the vegetable production system). Carrot and green onion were grown in a greenhouse for 130 d and 150 d. Phoxim solution (100 ml) was poured into each pot around the roots 14d before plant harvest. Results showed that mycorrhizal colonization was higher than 70%, and phoxim application inhibited AM colonization on carrot but not on green onion. Compared with the nonmycorrhizal controls, both shoot and root fresh weights of these two vegetables were significantly increased by AM inoculations irrespective of phoxim application rates. Phoxim concentrations in shoots, roots and soils were increased with the increase of phoxim application rate, but significantly decreased by the AM inoculations. Soil phosphatase activity was enhanced by both AM inocula, but not affected by phoxim application rate. In general, G. intraradices BEG 141 had more pronounced effects than G. mosseae BEG 167 on the increase of fresh weight production in both carrot and green onion, and the decrease of phoxim concentrations in plants and soils. Conclusions/Significance Our results indicate a promising potential of AM fungi for enhancing vegetable production and reducing organophosphorus pesticide residues in plant tissues and their growth media, as well as for the phytoremediation of organophosphorus pesticide-contaminated soils
The Lick AGN Monitoring Project 2011: Reverberation Mapping of Markarian 50
The Lick AGN Monitoring Project 2011 observing campaign was carried out over
the course of 11 weeks in Spring 2011. Here we present the first results from
this program, a measurement of the broad-line reverberation lag in the Seyfert
1 galaxy Mrk 50. Combining our data with supplemental observations obtained
prior to the start of the main observing campaign, our dataset covers a total
duration of 4.5 months. During this time, Mrk 50 was highly variable,
exhibiting a maximum variability amplitude of a factor of 4 in the U-band
continuum and a factor of 2 in the H-beta line. Using standard
cross-correlation techniques, we find that H-beta and H-gamma lag the V-band
continuum by tau_cen = 10.64(-0.93,+0.82) and 8.43(-1.28,+1.30) days,
respectively, while the lag of He II 4686 is unresolved. The H-beta line
exhibits a symmetric velocity-resolved reverberation signature with shorter
lags in the high-velocity wings than in the line core, consistent with an
origin in a broad-line region dominated by orbital motion rather than infall or
outflow. Assuming a virial normalization factor of f=5.25, the virial estimate
of the black hole mass is (3.2+-0.5)*10^7 solar masses. These observations
demonstrate that Mrk 50 is among the most promising nearby active galaxies for
detailed investigations of broad-line region structure and dynamics.Comment: Accepted for publication in ApJ Letters. 6 pages, 4 figure
The Lick AGN Monitoring Project 2011: Dynamical Modeling of the Broad-Line Region
We present models of the H-emitting broad-line region (BLR) in seven
Seyfert 1 galaxies from the Lick AGN (Active Galactic Nucleus) Monitoring
Project 2011 sample, drawing inferences on the BLR structure and dynamics as
well as the mass of the central supermassive black hole. We find that the BLR
is generally a thick disk, viewed close to face-on, with preferential emission
back toward the ionizing source. The dynamics in our sample range from
near-circular elliptical orbits to inflowing or outflowing trajectories. We
measure black hole masses of for PG 1310108, for Mrk 50,
for Mrk 141, for Mrk 279,
for Mrk 1511, for NGC 4593, and
for Zw 229015. We use these black hole mass
measurements along with cross-correlation time lags and line widths to recover
the scale factor used in traditional reverberation mapping measurements.
Combining our results with other studies that use this modeling technique,
bringing our sample size to 16, we calculate a scale factor that can be used
for measuring black hole masses in other reverberation mapping campaigns. When
using the root-mean-square (rms) spectrum and using the line dispersion to
measure the line width, we find . Finally, we search for correlations between and other AGN
and BLR parameters and find marginal evidence that is correlated with
and the BLR inclination angle, but no significant evidence of a
correlation with the AGN luminosity or Eddington ratio.Comment: 26 pages, 14 figures. Accepted for publication in Ap
Long-term field metal extraction by pelargonium:phytoextraction efficiency in relation to plant maturity
The long length of periods required for effective soil remediation via phytoextraction constitutes a weak point that reduces its industrial use. However, these calculated periods are mainly based on short-term and/or hydroponic controlled experiments. Moreover, only a few studies concern more than one metal, although soils are scarcely polluted by only one element.In this scientific context, the phytoextraction of metals and metalloids (Pb, Cd, Zn, Cu,and As) by Pelargonium was measured after a long-term field experiment. Both bulk and rhizosphere soils were analyzed in order to determine the mechanisms involved in soil-root transfer. First, a strong increase in lead phytoextraction was observed with plant maturity, significantly reducing the length of the period required for remediation. Rhizosphere Pb, Zn, Cu, Cd, and As accumulation was observed (compared to bulk soil), indicating metal mobilization by the plant, perhaps in relation to root activity. Moreover, metal phytoextraction and translocation were found to be a function of the metals’ nature. These results, taken altogether, suggest that Pelargonium could be used as a multi-metal hyperaccumulator under multi-metal soil contamination conditions, and they also provide an interesting insight for improving field phytoextraction remediation in terms of the length of time required, promoting this biological technique
The Enigmatic Young Object: Walker 90/V590 Monocerotis
We assess the evolutionary status of the intriguing object Walker 90/V590
Mon, which is located about 20 arcminutes northwest of the Cone Nebula near the
center of the open cluster NGC 2264. This object, according to its most recent
optical spectral type determination (B7), which we confirmed, is at least 3
magnitudes too faint in V for the cluster distance, but it shows the classical
signs of a young pre-main sequence object, such as highly variable Halpha
emission, Mg II emission, IR excess, UV continuum, and optical variability. We
analyzed a collection of archival and original data on Walker 90, covering 45
years including photometry, imaging, and spectroscopic data ranging from
ultraviolet to near-infrared wavelengths. According to star formation
processes, it is expected that, as this object clears its primordial
surroundings, it should become optically brighter, show a weakening of its IR
excess and present decreasing line emissions. This behavior is supported by our
observations and analysis, but timescales are expected to be longer than the
one observed here. Based on photometric data secured in 2007, we find Walker 90
at its brightest recorded optical magnitude. We document an evolution in
spectral type over the past five decades (from A2/A3 to currently B7 and as
early as B4), along with a decrease in the near-infrared K fluxes. From
near-infrared images secured in 2004, Walker 90 appears as a point source
placing an upper limit of 0.1 arcsec for its diameter. We conclude that many
observational features are explained if W90 is a flared disk system, surrounded
by an inclined optically thick accretion disk.Comment: 13 pages, 19 figure
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