60 research outputs found
Fine-scale genetic structure and parentage in Urocitellus beldingi
Urocitellus beldingi (Belding\u27s ground squirrel), previously known as Spermophilus beldingi, is a social, montane rodent that occupies alpine and subalpine meadows in the Sierra Nevadas (Helgen et al. 2009). The Tioga Pass meadow (Mono Co. CA) population has been studied behaviorally and demographically for several decades. Microsatellites were developed for this species and conditions for polymerase chain reaction (PCR) were defined. Nine microsatellite loci amplified adequately and were in Hardy-Weinberg equilibrium, displaying an average heterozygosity of 0.67±0.19. These nine microsatellite loci were analyzed via PCR to elucidate the fine scale genetic structure, offering insight into population health, stochastic events, and dispersal. Two populations were identified, corresponding to the elevation differences between the sites (FST = 0.054605 pm) of 8.66. These populations appear to maintain a stable size and are not adversely affected by inbreeding. Urocitellus beldingi maternity can be deduced by observing female burrows usage during gestation and which offspring first emerge from the burrow associated with that particular female. Paternity, however, can only be posited by observation of mating because the species exhibits multiple mating in both sexes, though not all matings necessarily result in offspring. Multiple paternity has been previously verified through allozyme analysis. Microsatellites were used to verify maternity and determine paternity. Analysis of ten litters demonstrated an average of 1 father per 1.35 pups in a litter. Sibship deduced from maternity and paternity analysis was then compared with previously collected behavioral data. While previous observations indicate preference of fullsib play partners in juveniles, our findings do not corroborate this, though the results were not significant
Quantum time transfer for freespace quantum networking
Timing requirements for long-range quantum networking are driven by the
necessity of synchronizing the arrival of photons, from independent sources,
for Bell-state measurements. Thus, characteristics such as repetition rate and
pulse duration influence the precision required to enable quantum networking
tasks such as teleportation and entanglement swapping. Some solutions have been
proposed utilizing classical laser pulses, frequency combs, and bi-photon
sources. In this article, we explore the utility of the latter method since it
is based upon quantum phenomena, which makes it naturally covert, and
potentially quantum secure. Furthermore, it relies on relatively low technology
quantum-photon sources and detection equipment, but provides picosecond timing
precision even under high loss and high noise channel conditions representative
of daytime space-Earth links. Therefore, this method is potentially relevant
for daytime space-Earth quantum networking and/or providing high-precision
secure timing in GPS denied environments
Identification of 13 Cepheids and 333 Other Variables in M31
We present Cousins and band photometry of variable stars in a
region in the disk of M31 galaxy, obtained during 141
nights. Of the 26 Cepheid variables present in the region, two are newly
discovered, 11 are classified as Cepheids for the first time and 13 are
confirmed as Cepheids. The extensive photometry of these Cepheids enabled us to
determine precise phase and amplitude of pulsation which ranges from 0.11 to
0.48 mag in band. The period of variability ranges from 7.5 to 56
days. The period-luminosity diagram is used to derive a distance modulus of
24.490.11 mag for M31 galaxy. We also report variability in 333 other
stars, of them, 115 stars appear to be long period variables, 2 suspected
eclipsing binaries and remaining 216 are irregular variables.Comment: Accepted for publication in A&A, 9 figures, the paper and figures
with better resolution can be downloaded from
http://cdfinfo.in2p3.fr/Downloads/cosmobs/yogesh/paper
Two-Way Quantum Time Transfer: A Method for Daytime Space-Earth Links
Remote clock synchronization is crucial for many classical and quantum
network applications. Current state-of-the-art remote clock synchronization
techniques achieve femtosecond-scale clock stability utilizing frequency combs,
which are supplementary to quantum-networking hardware. Demonstrating an
alternative, we synchronize two remote clocks across our freespace testbed
using a method called two-way quantum time transfer (QTT). In one second we
reach picosecond-scale timing precision under very lossy and noisy channel
conditions representative of daytime space-Earth links with commercial
off-the-shelf quantum-photon sources and detection equipment. This work
demonstrates how QTT is potentially relevant for daytime space-Earth quantum
networking and/or providing high-precision secure timing in GPS-denied
environments.Comment: arXiv admin note: text overlap with arXiv:2211.0073
The First Known Mira-type Variable Star in IC 1613
King, Modjaz, & Li (1999) discovered Nova 1999 in IC1613 at Lick Observatory.
Both Fugazza et al. (2000) and Borissova et al. (2000) questioned this
classification, because they were able to detect the star on images obtained in
previous years. In infrared frames taken on Oct. 15, 1998, the Nova 1999 has
(J-K) = 1.14 and K = 14.69 mag. Our light curve study, based primarily on 92
unfiltered Lick images, suggested that the object could be a Mira-type variable
with a period of 640.7 days. This period is very close to that obtained by
Fugazza et al. (2000) - 631 days. The star is overluminous with respect to the
period-luminosity (PL) relation derived by Feast et al. (1989) for Mira
variables in the LMC. At longer periods (P > 400 ~ days), many LMC Miras show
such behavior and the PL relation appears to break down. It is possible that
the situation in IC1613 is similar. An optical spectrum obtained with the
Keck-II telescope shows features typical of M3Ie or M3IIIe stars. We conclude
that the star is a normal long-period M-type Mira variable, the first such star
confirmed in IC1613.Comment: 5 pages, 5 figures, accepted in A&
Magnetic field structure in single late-type giants: The effectively single giant V390 Aur
We have studied the active giant V390 Aur using spectropolarimetry to obtain
direct and simultaneous measurements of the magnetic field and the activity
indicators in order to get a precise insight of its activity. We used the
spectropolarimeter NARVAL at the Bernard Lyot Telescope (Observatoire du Pic du
Midi, France) to obtain a series of Stokes I and Stokes V profiles. The Least
Square deconvolution (LSD) technique was applied to detect the Zeeman signature
of the magnetic field in each of our 13 observations and to measure its
longitudinal component. We could also monitor the CaII K & H and IR triplet, as
well as the H_alpha lines which are activity indicators. In order to
reconstruct the magnetic field geometry of V390 Aur, we applied the Zeeman
Doppler Imaging (ZDI) inversion method and present a map for the magnetic
field. Based on the obtained spectra, we also refined the fundamental
parameters of the star and the Li abundance. The ZDI revealed a structure in
the radial magnetic field consisting of a polar magnetic spot of positive
polarity and several negative spots at lower latitude. A high latitude belt is
present on the azimuthal field map, indicative of a toroidal field close to the
surface. It was found that the photometric period cannot fit the behaviour of
the activity indicators formed in the chromosphere. Their behaviour suggests
slower rotation compared to the photosphere, but our dataset is too short to be
able to estimate the exact periods for them.Accepted for publication in A&A All
these results can be explained in terms of an \alpha-\omega dynamo operation,
taking into account the stellar structure and rotation properties of V390 Aur
that we study using up to-date stellar models computed at solar metallicity.
The calculated Rossby number also points to a very efficient dynamoComment: To appear in Astronomy & Astrophysics, 8 pages, 5 figure
Optical spectroscopy of X-Mega targets in the Carina nebula - VII On the multiplicity of Tr 16-112, HD 93343 and HD 93250
We present the results of a spectroscopic monitoring campaign devoted to
three O-type stars in the Carina nebula. We derive the full SB2 orbital
solution of the binary system Tr 16-112, an exceptional dissymmetrical system
consisting of an O5.5-6V((f?p)) primary and a B2V-III secondary. We also
report on low-amplitude brightness variations in Tr 16-112 that are likely due
to the ellipsoidal shape of the O5.5-6 primary revolving in an eccentric orbit
around the system's centre of mass. We detect for the first time a clear SB2
binary signature in the spectrum of HD 93343 (O8 + O8), although our data are
not sufficient to establish an orbital solution. This system also displays low
amplitude photometric modulations. On the other hand, no indication of
multiplicity is found in the optical spectra of HD 93250. Finally, we discuss
the general properties of multiple massive stars in the Carina OB1 association.Comment: Accepted for publication in MNRA
Four-colour photometry of eclipsing binaries. XL, uvby light curves for the B-type systems DW Carinae, BF Centauri, AC Velorum, and NSV 5783
Aims. In order to increase the limited number of B-stars with accurately known dimensions, and also the number of well studied eclipsing binaries in open clusters, we have undertaken observations and studies of four southern double-lined eclipsing B-type binaries; DWCar, BF Cen, ACVel, and NSV 5783.
Methods. Complete uvby light curves were observed between January 1982 and April 1991 at the Danish 0.5 m telescope at ESO La Silla, since 1985 known as the Strömgren Automatic Telescope (SAT). Standard indices for the systems and the comparison stars,as well as additional minima observations for ACVel, have been obtained later at SAT. For DWCar and ACVel, high-resolution spectra for definitive spectroscopic orbits have also been obtained; they are presented as part of the detailed analyses of these systems.
A few spectra of NSV 5783 are included in the present paper.
Results. For all four systems, the first modern accurate light curves have been established. DWCar is a detached system consisting of two nearly identical components. It is member of the young open cluster Cr228. A detailed analysis, based on the new light curves and 29 high-resolution spectra, is published separately. BFCen is semidetached and is member of NGC 3766. Modern spectra are
needed for a detailed study. ACVel is a detached system with at least one more star. A full analysis, based on the new light curves and 18 high-resolution spectra, is published separately. NSV 5783 is discovered to be an eclipsing binary consisting of two well-detached
components in an 11-day period eccentric (e = 0.18) orbit. Secondary eclipse is practically total. From the light curves and a few high-resolution spectra, accurate photometric elements and preliminary absolute dimensions have been determined. The quite similar components have masses of about 5 M and radii of about 3.5 R, and they seem to have evolved just slightly off the ZAMS. The
measured rotational velocities (≈150 km s−1) are about 6 times those corresponding to pseudosynchronization
Measurement of directional range components of nuclear recoil tracks in a fiducialised dark matter detector
We present results from the first measurement of axial range components of fiducialized neutron induced nuclear recoil tracks using the DRIFT directional dark matter detector. Nuclear recoil events are fiducialized in the DRIFT experiment using temporal charge carrier separations between different species of anions in 30:10:1 Torr of CS:CF:O gas mixture. For this measurement, neutron-induced nuclear recoil tracks were generated by exposing the detector to Cf source from different directions. Using these events, the sensitivity of the detector to the expected axial directional signatures were investigated as the neutron source was moved from one detector axis to another. Results obtained from these measurements show clear sensitivity of the DRIFT detector to the axial directional signatures in this fiducialization gas mode
Four-colour photometry of eclipsing binaries. XLI uvby light curves for AD Bootis, HW Canis Majoris, SW Canis Majoris, V636 Centauri, VZ Hydrae, and WZ Ophiuchi
CONTEXT: Accurate mass, radius, and abundance determinations from binaries
provide important information on stellar evolution, fundamental to central
fields in modern astrophysics and cosmology.
AIMS: Within the long-term Copenhagen Binary Project, we aim to obtain
high-quality light curves and standard photometry for double-lined detached
eclipsing binaries with late A, F, and G type main-sequence components, needed
for the determination of accurate absolute dimensions and abundances, and for
detailed comparisons with results from recent stellar evolutionary models.
METHODS: Between March 1985 and July 2007, we carried out photometric
observations of AD Boo, HW CMA, SW CMa, V636 Cen, VZ Hya, and WZ Oph at the
Str"omgren Automatic Telescope at ESO, La Silla.
RESULTS: We obtained complete uvby light curves, ephemerides, and standard
uvby\beta indices for all six systems.For V636 Cen and HW CMa, we present the
first modern light curves, whereas for AD Boo, SW CMa, VZ Hya, and WZ Oph, they
are both more accurate and more complete than earlier data. Due to a high
orbital eccentricity (e = 0.50), combined with a low orbital inclination (i =
84.7), only one eclipse, close to periastron, occurs for HW CMa. For the two
other eccentric systems, V636 Cen (e = 0.134) and SW CMa (e = 0.316), apsidal
motion has been detected with periods of 5270 +/- 335 and 14900 +/- 3600 years,
respectively.Comment: Only change is: Bottom lines (hopefully) not truncated anymore.
Accepted for publication in Astonomy & Astrophysic
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