Maria Mitchell Association

IntroductionBarbarian asteroids are unique because of their wide negative branch of the polarisation phase curves. Their name comes from (234) Barbara for which such behaviour was first observed [1]. They reside in the inner  part of the Main Belt and are mainly of the L taxonomic class. Since magnitude-phase curves are sensitive to the asteroid surface properties, the question arises as to whether Barbarian asteroids' magnitude-phase curves are also anomalous. To answer this, we are carrying out photometric observations of Barbarian asteroids, fitting their phase curves with the [H,G], [H, G12], and [H, G1, G2] phase functions. These parameters are then compared with those of other asteroids in search of deviations. The results for (599) Luisa and (729) Watsonia have been presented in [2]. At the conference, we will show mag-phase curves for another three Barbarians: (234) Barbara, (236) Honoria, and (980) Anacostia.Observations and ReductionPhotometric observations were carried out using several telescopes in different observatories in the Johnson R band. For Honoria, we collected data during its 2012 opposition and for Barbara and Anacostia during the 2022 and 2023 oppositions, respectively. CCD images were reduced in a standard way, including bias, dark subtraction, and flat-field correction. The magnitudes of asteroids and standard stars were obtained with aperture photometry using the Photometry Pipeline package [3]. ResultsFor each asteroid, composite lightcurves from data collected during the opposition were obtained. Synodic periods were derived by a standard Fourier series fit procedure (Fig. 1). The composite lightcurves were used to correct the partial lightcurves (which did not cover all rotation phases) to the same level of maximum brightness. The magnitudes of the maxima of brightness from different nights were then plotted against the phase angle, producing mag-phase curves, which were fitted with three different phase functions (Fig. 2). This allowed us to compare the obtained G1, G2 parameters with similar parameters obtained by [4] for 127 Main Belt asteroids. The final results will be presented at the conference.Fig. 1. Composite lightcurve of (980) AnacostiaFig. 2. Magnitude-phase curve of (980) Anacostia, based on maxima of brightness obtained from the composite lightcurveReferences[1] Cellino, A., et al. (2006) The strange polarimetric behavior of asteroid (234) Barbara, Icarus, 180, 565[2] Mykhailova, S., et al. (2023) What do the phase curves tell us about the Barbarian asteroids. Asteroids, Comets, Meteors Conference, Flagstaff, Arizona. LPI Contribution No. 2851, 2023, id. 2202[3] Mommert, M. (2017) PHOTOMETRYPIPELINE: An automated pipeline for calibrated photometry, Astronomy and Computing, 18, 47[4] Shevchenko, V. G., et al. (2016). Planetary and Space Science, 123,

We present Keck Cosmic Web Imager (KCWI) Ly$\alpha$ integral field spectroscopy of the fields surrounding 14 Damped Ly$\alpha$ absorbers (DLAs) at $z \approx 2$. Of these 14 DLAs, 9 have high metallicities ([M/H]$~> -0.3$), and 4 of those 9 feature a CO-emitting galaxy at an impact parameter $\lesssim 30$ kpc. Our search reaches median Ly$\alpha$ line flux sensitivities of $\sim 2 \times 10^{-17}$ erg s$^{-1}$ cm$^{-2}$ over apertures of $\sim6$ kpc and out to impact parameters of $\sim50$ kpc. We recover the Ly$\alpha$ flux of three known Ly$\alpha$-emitting H I-selected galaxies in our sample. In addition, we find two Ly$\alpha$ emitters at impact parameters of $\approx 50-70$ kpc from the high metallicity DLA at $z \approx 1.96$ toward QSO B0551-366. This field also contains a massive CO-emitting galaxy at an impact parameter of $\approx 15$ kpc. Apart from the field with QSO B0551-366, we do not detect significant Ly$\alpha$ emission in any of the remaining 8 high-metallicity DLA fields. Considering the depth of our observations and our ability to recover previously known Ly$\alpha$ emitters, we conclude that H I-selected galaxies associated with high-metallicity DLAs at $z \approx 2$ are dusty, and therefore might feature low Ly$\alpha$ escape fractions. Our results indicate that complementary approaches -- using Ly$\alpha$, CO, H$\alpha$, and [C II] 158$\mu$m emission -- are necessary to identify the wide range of galaxy types associated with $z \approx 2$ DLAs.

TU Tau (=HD 38218 = HIP 27135) is a binary system consisting of a C-N carbon star primary and an A-type secondary. We report on new photometry and spectroscopy which tracked the recent disappearance of the A-star secondary. The dimming of the A star was gradual and irregular, with one or more brief brightenings, implying the presence of nonhomogeneities in the carbon star outflow. We also present evidence that the A star is actively accreting s-process enriched material from the carbon star and suggest that it will therefore eventually evolve into a Barium giant. This is an important system as well because the A-type star can serve as a probe of the outer atmosphere of the carbon star.

Abstract Fast radio burst (FRB) 190608 was detected by the Australian Square Kilometre Array Pathfinder (ASKAP) and localized to a spiral galaxy at in the Sloan Digital Sky Survey (SDSS) footprint. The burst has a large dispersion measure ( ) compared to the expected cosmic average at its redshift. It also has a large rotation measure ( ) and scattering timescale (τ = 3.3 ms at 1.28 GHz). Chittidi et al. perform a detailed analysis of the ultraviolet and optical emission of the host galaxy and estimate the host DM contribution to be . This work complements theirs and reports the analysis of the optical data of galaxies in the foreground of FRB 190608 in order to explore their contributions to the FRB signal. Together, the two studies delineate an observationally driven, end-to-end study of matter distribution along an FRB sightline, the first study of its kind. Combining our Keck Cosmic Web Imager (KCWI) observations and public SDSS data, we estimate the expected cosmic dispersion measure along the sightline to FRB 190608. We first estimate the contribution of hot, ionized gas in intervening virialized halos ( ). Then, using the Monte Carlo Physarum Machine methodology, we produce a 3D map of ionized gas in cosmic web filaments and compute the DM contribution from matter outside halos ( ). This implies that a greater fraction of ionized gas along this sightline is extant outside virialized halos. We also investigate whether the intervening halos can account for the large FRB rotation measure and pulse width and conclude that it is implausible. Both the pulse broadening and the large Faraday rotation likely arise from the progenitor environment or the host galaxy.

A new epoxy monomer, namely, tetraglycidyl-1,2-aminobenzamide (ER), was synthesized by condensation of the amines with epichlorohydrin in a basic medium. The obtained epoxy monomer was characterized by FT-IR and 1H NMR spectroscopy. Rheological properties of this monomer were determined using an advanced rheometer. Subsequently, the synthesized ER monomer was investigated as corrosion inhibitor for carbon steel in 1 M HCl solution. The adsorption properties of ER were analyzed by electrochemical, surface investigation and theoretical computational studies using DFT and molecular dynamics (MD). Results showed a high dependence of the viscosity of ER on temperature and concentration, and also, that ER has better inhibition performance. A good agreement between the results derived from computational (MD and DFT) and experimental methods was observed. The thermodynamic parameters, along with the kinetic parameters, showed that the adsorption of ER molecules onto carbon steel surface obeyed the Langmuir isotherm model, and the adsorption at metal–electrolyte interfaces involved both chemical and physical adsorption, but predominantly chemisorption mechanism.

ABSTRACT We report the discovery and analysis of the most metal-poor damped Lyα (DLA) system currently known, which also displays the Lyman series absorption lines of neutral deuterium. The average [O/H] abundance of this system is [O/H] = −2.804 ± 0.015, which includes an absorption component with [O/H] = −3.07 ± 0.03. Despite the unfortunate blending of many weak D i absorption lines, we report a precise measurement of the deuterium abundance of this system. Using the six highest-quality and self-consistently analyzed measures of D/H in DLAs, we report tentative evidence for a subtle decrease of D/H with increasing metallicity. This trend must be confirmed with future high-precision D/H measurements spanning a range of metallicity. A weighted mean of these six independent measures provides our best estimate of the primordial abundance of deuterium, 105 (D/H)P = 2.547 ± 0.033 ( ). We perform a series of detailed Monte Carlo calculations of Big Bang nucleosynthesis (BBN) that incorporate the latest determinations of several key nuclear reaction cross-sections, and propagate their associated uncertainty. Combining our measurement of (D/H)P with these BBN calculations yields an estimate of the cosmic baryon density, 100 ΩB,0 h 2(BBN) = 2.156 ± 0.020, if we adopt the most recent theoretical determination of the reaction rate. This measure of ΩB,0 h 2 differs by ∼2.3σ from the Standard Model value estimated from the Planck observations of the cosmic microwave background. Using instead a reaction rate that is based on the best available experimental cross-section data, we estimate 100 ΩB,0 h 2(BBN) = 2.260 ± 0.034, which is in somewhat better agreement with the Planck value. Forthcoming measurements of the crucial cross-section may shed further light on this discrepancy.

The inhibition of mild steel corrosion in 1 M HCl by three newly synthesized 2,4-diamino-5-(phenylthio)-5H-chromeno[2,3-b]pyridine-3-carbonitriles was studied using the weight loss method, electrochemical techniques, surface morphology studies and theoretical methods.

We use the HB morphology of 48 Galactic GCs to study the radial distributions of the different stellar populations known to exist in globular clusters. Assuming that the (extremely) blue HB stars correspond to stars enriched in Helium and light elements, we compare the radial distributions of stars selected according to colour on the HB to trace the distribution of the secondary stellar populations in globular clusters. Unlike other cases, our data show that the populations are well mixed in 80% of the cases studied. This provides some constraints on the mechanisms proposed to pollute the interstellar medium in young globular clusters.

Abstract Nantucket, Massachusetts, has one of the last remaining commercial fisheries of the bay scallop Argopecten irradians, which is based largely on natural recruitment. Though previously thought to spawn only once in early summer at age 1, individuals of the northern subspecies often spawn again in late summer or fall, and recruits from this second spawning can survive to reproduce again in their second summer. We formulated an age-based Leslie matrix model and estimated population growth rate with and without a second spawn based on data from 5 years of life history research. Elasticity analysis revealed that the population growth rate was most sensitive to juvenile survival, the major factor in recruitment rate, and year-1 adult fertility was a close second. We varied those two rates randomly in a stochastic matrix model, which represented the effect of environmental fluctuations on population growth. A life history modeled with a second spawn had a negligible effect on the deterministic population growth rate under constant conditions, but under variable conditions the second spawn increased the mean of the stochastic growth rates up to 58.3% over that of a single early-spawning life history. These results suggest that the second spawn is a successful bet-hedging strategy. The northern bay scallop increases its chances for successful recruitment in a variable environment by spreading reproductive effort over more than one period in a season. This strategy appears to have sustained the Nantucket scallop population in spite of severe annual fluctuations and the eventual collapse seen in other locations. Received March 6, 2015; accepted June 19, 2015

We investigate the possibility of maser amplification in hydrogen recombination lines from the galaxies of first generation, at z<~30. Combining analytical and computational approaches, we show that the transitions between the hydrogen Rydberg energy levels induced by the radiation from the ionizing star and by the (warmer than currently) Cosmic Microwave Background can produce noticeable differences in the population distribution, as compared with previous computations for the contemporary H+ regions, most of which ignored the processes induced by the star radiation. In particular, the low (n<~30) alpha-transitions show an increased tendency toward population inversion, when ionization of the H+ region is caused by a very hot star at high redshift. The resulting maser/laser amplification can increase the brightness of the emitted lines and make them detectable. However, the limiting effects of maser saturation will probably not allow maser gains to exceed one or two orders of magnitude.