Absolute dimensions of the G7+K7 eclipsing binary star IM Virginis: Discrepancies with stellar evolution models

We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IM Vir, composed of a G7-type primary and a K7 secondary. With these observations we derive accurate absolute masses and radii of M(1) = 0.981 +/- 0.012 M(Sun), M(2) = 0.6644 +/- 0.0048 M(Sun), R(1) = 1.061 +/- 0.016 R(Sun), and R(2) = 0.681 +/- 0.013 R(Sun) for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 +/- 100 K and 4250 +/- 130 K. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory. We find that both stars are larger than the models predict, by 3.7% for the primary and 7.5% for the secondary, as well as cooler than expected, by 100 K and 150 K, respectively. These discrepancies are in line with previously reported differences in low-mass stars, and are believed to be caused by chromospheric activity, which is not accounted for in current models. The effect is not confined to low-mass stars: the rapidly-rotating primary of IM Vir joins the growing list of objects of near-solar mass (but still with convective envelopes) that show similar anomalies. The comparison with the models suggests an age of 2.4 Gyr for the system, and a metallicity [Fe/H] of approximately -0.3 that is consistent with other indications, but requires confirmation.Comment: 14 pages, 13 figures. Accepted for publication in Ap

F-algebra–Rinehart pairs and super F-algebroids

We define F-algebra--Rinehart pairs and super F-algebroids and study theconnection between them.<br

The Mass-Radius(-Rotation?) Relation for Low-Mass Stars

The fundamental properties of low-mass stars are not as well understood as those of their more massive counterparts. The best method for constraining these properties, especially masses and radii, is to study eclipsing binary systems, but only a small number of late-type (M0 or later) systems have been identified and well-characterized to date. We present the discovery and characterization of six new M dwarf eclipsing binary systems. The twelve stars in these eclipsing systems have masses spanning 0.38-0.59 Msun and orbital periods of 0.6--1.7 days, with typical uncertainties of ~0.3% in mass and 0.5--2.0% in radius. Combined with six known systems with high-precision measurements, our results reveal an intriguing trend in the low-mass regime. For stars with M=0.35-0.80 Msun, components in short-period binary systems (P<1 day; 12 stars) have radii which are inflated by up to 10% (mean=4.8+/-1.0%) with respect to evolutionary models for low-mass main-sequence stars, whereas components in longer-period systems (>1.5 days; 12 stars) tend to have smaller radii (mean=1.7+/-0.7%). This trend supports the hypothesis that short-period systems are inflated by the influence of the close companion, most likely because they are tidally locked into very high rotation speeds that enhance activity and inhibit convection. In summary, very close binary systems are not representative of typical M dwarfs, but our results for longer-period systems indicate that the evolutionary models are broadly valid in the M~0.35-0.80 Msun regime.Comment: Accepted to ApJ; 21 pages, 10 figures, 8 tables in emulateapj format. The full contents of Table 4 are included in the submission as tab4.tx

Green chemistry and environmental processes

Funding Information: Acknowledgments: Portuguese FCT—Fundação para a Ciência e a Tecnologia, I.P., under the Scientific Employment Stimulus—Institutional Call (CEECINST/00102/2018) and Associate Laboratory for Green Chemistry—LAQV, financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020) and the Spanish Project ref. RTI 2018-099224-B100 funded by ERDF/Ministry of Science, Innovation and Universities. S.M.-T. also acknowledges the Ramón y Cajal contract (RYC-2019-026634-I/AEI/10.13039/501100011033) from MINECO.publishersversionpublishe

Social policy in a global society : parallels and lessons from the Canada - Latin America experience

Meeting: Social Policy in a Global Society, 26-28 Oct. 1994, Ottawa, ON, C

Spitzer Infrared Observations and Independent Validation of the Transiting Super-Earth CoRoT-7b

The detection and characterization of the first transiting super-Earth, CoRoT-7 b, has required an unprecedented effort in terms of telescope time and analysis. Although the star does display a radial velocity signal at the period of the planet, this has been difficult to disentangle from the intrinsic stellar variability, and pinning down the velocity amplitude has been very challenging. As a result, the precise value of the mass of the planet - and even the extent to which it can be considered to be confirmed - have been debated in the recent literature, with six mass measurements published so far based on the same spectroscopic observations, ranging from about 2 to 8 Earth masses. Here we report on an independent validation of the planet discovery, using one of the fundamental properties of a transit signal: its achromaticity. We observed four transits of CoRoT-7 b with Spitzer, in order to determine whether the depth of the transit signal in the near-infrared is consistent with that observed in the CoRoT bandpass, as expected for a planet. We detected the transit and found an average depth of 0.426 {\pm} 0.115 mmag at 4.5 {\mu}m, which is in good agreement with the depth of 0.350 {\pm} 0.011 mmag found by CoRoT. These observations place important constraints on the kinds of astrophysical false positives that could mimic the signal. Combining this with additional constraints reported earlier, we performed an exhaustive exploration of possible blends scenarios for CoRoT-7 b using the BLENDER technique. We are able to rule out the vast majority of false positives, and the remaining ones are found to be much less likely than a true transiting planet. We thus validate CoRoT-7 b as a bona-fide planet with a very high degree of confidence, independently of any radial-velocity information. Our Spitzer observations have additionally allowed us to significantly improve the ephemeris of the planet.Comment: Accepted by Ap

LEARNING FOR THE GENERATION OF SHARED VALUE: CHALLENGE OF THE MANAGEMENT PROGRAM OF A PUBLIC UNIVERSITY

Companies as organizations focused on the fulfillment of particular objectives direct and maximizing limited resources in the function of satisfying needs in society, however, motivated by profit and rarely conceived of their investors as sufficient, causing neglect and distancing from the commitment to ethical and responsible management of resources, oriented by market orders, under policies more concerned with their profits than with operational practices that, in addition to improving their competitiveness, help to improve social conditions in a reactivation process after the pandemic experienced, contribute to the quality of life in general in the communities involved in their production processes, in other words, the generation of shared value (SV). The results of a study that sought to identify, through the perception delivered by students and graduates of an administration program of a public university, the level of perception of learning that allows contributing to the culture in the generation of shared value in organizations. It is a population that, due to its formation, challenges them with the transfer of knowledge that contributes to the economic reactivation, as well as to the generation of SV in the organizations. The study is based on Porter's and Kramer's ideas on preconceiving a) products and markets, b) redefining productivity in the value chain, and c) building support clusters. The methodology implemented for the analysis was mixed, using the survey as a data collection instrument. The results show that the students and graduates of the program observed show that there is a medium-low environment in the three concepts evaluated, with a medium level of 40%, a low level of 35% and a high level of only 24%

Learning For The Generation Of Shared Value: Challenge Of The Management Program Of A Public University

Companies as organizations focused on the fulfillment of particular objectives direct and maximizing limited resources in the function of satisfying needs in society, however, motivated by profit and rarely conceived of their investors as sufficient, causing neglect and distancing from the commitment to ethical and responsible management of resources, oriented by market orders, under policies more concerned with their profits than with operational practices that, in addition to improving their competitiveness, help to improve social conditions in a reactivation process after the pandemic experienced, contribute to the quality of life in general in the communities involved in their production processes, in other words, the generation of shared value (SV). The results of a study that sought to identify, through the perception delivered by students and graduates of an administration program of a public university, the level of perception of learning that allows contributing to the culture in the generation of shared value in organizations. It is a population that, due to its formation, challenges them with the transfer of knowledge that contributes to the economic reactivation, as well as to the generation of SV in the organizations. The study is based on Porter's and Kramer's ideas on preconceiving a) products and markets, b) redefining productivity in the value chain, and c) building support clusters. The methodology implemented for the analysis was mixed, using the survey as a data collection instrument. The results show that the students and graduates of the program observed show that there is a medium-low environment in the three concepts evaluated, with a medium level of 40%, a low level of 35% and a high level of only 24%