arXiv subjects

M. Gutierrez

Publications and source records attributed to M. Gutierrez.

8 recordsLinked to original sources

arXiv2026

Interferometric Survey of Stellar Parameters: Mass of the metallic A-type binary $\beta$ Aur

With the capabilities of the new visible CHARA/SPICA instrument and the multiple spectral band operation of CHARA, our goal is to resolve orbits of short-period binaries and develop a robust framework for combining interferometric, spectroscopic, and photometric observations into a single consistent model. For our target sample, we selected suitable binaries based on brightness, angular separation, and orbital properties based on the expected performance of the CHARA/SPICA instrument. As a case study, we analysed the bright eclipsing binary $\beta$ Aurigae, composed of two slightly evolved A1 stars. We combined new interferometric observations of $\beta$ Aur obtained with CHARA/SPICA, MIRC-X, and MYSTIC with archival MIRC data, radial velocities, and light curves. We first derived astrometric positions from interferometric observables and computed an orbital solution. Afterwards, we implemented a unified model, capable of tying interferometric modelling with the ellc code to simultaneously fit all observables using MCMC sampling. We performed a detailed analysis of the noise statistics of each data set and in the end we adopted a profile likelihood approach to account for underestimated noise and systematics. We derived a consistent orbital and physical solution for $\beta$ Aur through joint modelling. The inclusion of interferometric data tightly constrains the angular semi-major axis and inclination. Using profile likelihood to account for the different intrinsic levels of uncertainty of the fundamentally different observables, we derived the masses of the two stars, $M_1 = 2.359 \pm 0.005$ M$_S$ and $M_2 = 2.293 \pm 0.004$ M$_S$, their radii $R_1 = 2.752 \pm 0.002$ R$_S$ and $R_2 = 2.622 \pm 0.002$ R$_S$, and the distance to the binary, $d = 24.30\pm0.05$ pc.

astro-ph.SR↗

arXiv2026

CHARA/SPICA: The six-telescope visible combiner and near-infrared fringe tracker for the CHARA Array

The suite called Stellar Parameters and Images with a Cophased Array (SPICA) has two interferometric instruments installed at the focus of the CHARA Array located at Mount Wilson, CA. SPICA is made of SPICA-VIS, a fiber-fed six-beam visible spectrograph with three spectral resolutions, and SPICA-FT, a six-beam near-infrared fringe tracker for the fast stabilization of the fringes. SPICA is opening access to imaging in the visible domain with an unprecedented angular resolution down to 0.2 milliarcseconds. It has been designed around a large survey of fundamental parameters of stars over the Hertzsprung- Russell diagram, aiming at understanding the deviations from the standard empirical relations of stellar physics as a function of activity: limb darkening, multiplicity, rotation, winds, and environments. SPICA makes use of the advanced technologies in electron multiplying detectors in the visible and electron- avalanche photodiode arrays in the near-infrared. It benefits from the newly commissioned adaptive optics on the one-meter telescopes of the array. The modules of the visible instrument, SPICA-VIS, optimize the injection of light into single-mode fibers for spatial filtering before spectral dispersion in the image plane. The fringe tracker, SPICA-FT, performs group-delay and phase-delay tracking for six beams in the H band. SPICA-FT can use an all-in-one or ABCD encoding of the fringe signals. SPICA is operational on sky and is close to reaching the expected performance in low spectral resolution, in particular, for the Interferometric Survey of Stellar Parameters (ISSP). More work is still needed to achieve the ultimate performance in terms of sensitivity and to allow operations with higher spectral resolutions.

astro-ph.IM↗

arXiv2024

Newborn Be star systems observed shortly after mass transfer

Many classical Be stars acquire their very rapid rotation by mass and angular-momentum transfer in massive binaries. Short-lived intermediate-phase objects have only been discovered recently. Data archives and the literature have been searched for additional candidates exhibiting this patterns. Thirteen candidates were identified at various confidence levels. Adding to the two known systems identified as classical Be star+pre-subdwarf binaries (LB-1 and HR6819), two more (V742Cas, HD44637) could be confirmed with interferometry, with V742Cas setting a new record for the smallest visually observed angular semi-major axis, at a=0.663mas. Two further ones (V447Sct, V1362Cyg) are not resolved interferometrically, but other evidence puts them at the same confidence level as LB-1. V2174Cyg is a candidate with very high confidence, but was not observed interferometrically. The remaining ones are either candidates with varying levels of confidence. Of a mostly magnitude complete sample of 328 Be stars, 0.5-1% are found to have recently completed the mass overflow that led to their formation. Another 5% are systems with compact subdwarf companions, i.e., further evolved after a previous overflow, and possibly two more percent harbor white dwarfs. All these systems are of early B-subtypes, however, and if the original sample is restricted to early subtypes (136 objects), these percentages increase by a factor of about 2.5, while dropping to zero for the mid and late subtypes (together 204 objects). This strongly suggests that early- vs. mid- and late-type Be stars have differently weighted channels to acquire their rapid rotation, namely binary interaction vs. evolutionary spin-up.

astro-ph.SR↗

arXiv2024

Multiplicity of Galactic Cepheids from long-baseline interferometry V. High-accuracy orbital parallax and mass of SU Cygni

Cepheid masses are particularly necessary to help solving the mass discrepancy, while independent distance determinations provide crucial test of the period-luminosity relation and Gaia parallaxes. We used CHARA/MIRC to measure the astrometric positions of the high-contrast companion orbiting the Cepheid SU Cygni. We also present new radial velocity measurements from the HST. The combination of interferometric astrometry with optical and ultraviolet spectroscopy provides the full orbital elements of the system, in addition to component masses and the distance to the Cepheid system. We measured the mass of the Cepheid, $M_A = 4.859\pm0.058M_\odot$, and its two companions, $M_{Ba} = 3.595 \pm 0.033 M_\odot$ and $M_{Bb} = 1.546 \pm 0.009 M_\odot$. This is the most accurate existing measurement of the mass of a Galactic Cepheid (1.2%). Comparing with stellar evolution models, we show that the mass predicted is higher than the measured mass of the Cepheid, similar to conclusions of our previous work. We also measured the distance to the system to be $926.3 \pm 5.0$pc, i.e. an unprecedented parallax precision of $6\mu$as (0.5%), being the most precise and accurate distance for a Cepheid. Such precision is similar to what is expected by Gaia for the last data release (DR5 in $\sim$ 2030) for single stars fainter than G = 13, but is not guaranteed for stars as bright as SU Cyg. We demonstrated that evolutionary models remain inadequate in accurately reproducing the measured mass, often predicting higher masses for the expected metallicity, even when factors such as rotation or convective core overshooting are taken into account. Our precise distance measurement allowed us to compare prediction period-luminosity relations. We found a disagreement of 0.2-0.5 mag with relations calibrated from photometry, while relations calibrated from direct distance measurement are in better agreement.

astro-ph.SR↗

arXiv2021

Nanobeacon: A time calibration device for the KM3NeT neutrino telescope

The KM3NeT Collaboration is currently constructing a multi-site high-energy neutrino telescope in the Mediterranean Sea consisting of matrices of pressure-resistant glass spheres, each holding a set of 31 small-area photomultipliers. The main goals of the telescope are the observation of neutrino sources in the Universe and the measurement of the neutrino oscillation parameters with atmospheric neutrinos. Both extraterrestrial and atmospheric neutrinos are detected through the Cherenkov light induced in seawater by charged particles produced in neutrino interactions in the surrounding medium. A relative time synchronization between photomultipliers of the order of 1 ns is needed to guarantee the required angular resolution of the detector. Due to the large detector volumes to be instrumented by KM3NeT, a cost reduction of the different systems is a priority. To this end, the inexpensive Nanobeacon has been designed and developed by the KM3NeT Collaboration to be used for detector time-calibration studies. At present, more than 600 Nanobeacons have been already produced. The characterization of the optical pulse and the wavelength emission profile of the devices are critical for the time calibration. In this paper, the main features of the Nanobeacon design, production and operation, together with the main properties of the light pulse generated are described.

astro-ph.IM↗

arXiv2017

Fault-tolerant quantum error detection

Quantum computers will eventually reach a size at which quantum error correction becomes imperative. Quantum information can be protected from qubit imperfections and flawed control operations by encoding a single logical qubit in multiple physical qubits. This redundancy allows the extraction of error syndromes and the subsequent detection or correction of errors without destroying the logical state itself through direct measurement. Here we show the encoding and syndrome measurement of a fault-tolerant logical qubit via an error detection protocol on four physical qubits, represented by trapped atomic ions. This demonstrates for the first time the robustness of a fault-tolerant qubit to imperfections in the very operations used to encode it. The advantage persists in the face of large added error rates and experimental calibration errors.

quant-ph↗

arXiv2015

On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid

Golumbic, Lipshteyn and Stern \cite{Golumbic-epg} proved that every graph can be represented as the edge intersection graph of paths on a grid (EPG graph), i.e., one can associate with each vertex of the graph a nontrivial path on a rectangular grid such that two vertices are adjacent if and only if the corresponding paths share at least one edge of the grid. For a nonnegative integer $k$, $B_k$-EPG graphs are defined as EPG graphs admitting a model in which each path has at most $k$ bends. Circular-arc graphs are intersection graphs of open arcs of a circle. It is easy to see that every circular-arc graph is a $B_4$-EPG graph, by embedding the circle into a rectangle of the grid. In this paper, we prove that every circular-arc graph is $B_3$-EPG, and that there exist circular-arc graphs which are not $B_2$-EPG. If we restrict ourselves to rectangular representations (i.e., the union of the paths used in the model is contained in a rectangle of the grid), we obtain EPR (edge intersection of path in a rectangle) representations. We may define $B_k$-EPR graphs, $k\geq 0$, the same way as $B_k$-EPG graphs. Circular-arc graphs are clearly $B_4$-EPR graphs and we will show that there exist circular-arc graphs that are not $B_3$-EPR graphs. We also show that normal circular-arc graphs are $B_2$-EPR graphs and that there exist normal circular-arc graphs that are not $B_1$-EPR graphs. Finally, we characterize $B_1$-EPR graphs by a family of minimal forbidden induced subgraphs, and show that they form a subclass of normal Helly circular-arc graphs.

math.CO↗

arXiv2013

Multiple Isotope Magneto Optical Trap from a single diode laser

We present a Dual Isotope Magneto Optical Trap produced using a single diode laser. We generate all the optical frequencies needed for trapping both species using a fiber intensity modulator. All the optical frequencies are amplified simultaneously using a tapered amplifier. The independent control of each frequency is on the RF side rather than on the optical side. This introduces an enormous simplification for laser cooling applications that often require an acousto-optic modulator for each laser beam. Frequency changing capabilities are limited by the modulator bandwidth (10 GHz). Traps for more isotopes can be simply added by including additional RF frequencies to the modulator.

physics.atom-ph↗