Publications of the Astronomical Society of the Pacific最新文献

{"title":"Two-photon Production in Low-velocity Shocks","authors":"S. R. Kulkarni, J. Michael Shull","doi":"10.1088/1538-3873/acff85","DOIUrl":"https://doi.org/10.1088/1538-3873/acff85","url":null,"abstract":"The Galactic interstellar medium abounds in shocks with low velocities <italic toggle=\"yes\">v</italic>\u0000_{\u0000<italic toggle=\"yes\">s</italic>\u0000} ≲ 70 km s⁻¹. Some are descendants of higher velocity shocks, while others start off at low velocity (e.g., stellar bow shocks, intermediate velocity clouds, spiral density waves). Low-velocity shocks cool primarily via Ly<italic toggle=\"yes\">α</italic> and two-photon continuum, augmented by optical recombination lines (e.g., H<italic toggle=\"yes\">α</italic>), forbidden lines of metals and free-bound emission, free–free emission. The dark far-ultraviolet (FUV) sky, aided by the fact that the two-photon continuum peaks at 1400 Å, makes the FUV band an ideal tracer of low-velocity shocks. GALEX FUV images reaffirm this expectation, discovering faint and large interstellar structure in old supernova remnants and thin arcs stretching across the sky. Interstellar bow shocks are expected from fast stars from the Galactic disk passing through the numerous gas clouds in the local interstellar medium within 15 pc of the Sun. Using the bests atomic data available to date, we present convenient fitting formulae for yields of Ly<italic toggle=\"yes\">α</italic>, two-photon continuum, and H<italic toggle=\"yes\">α</italic> for pure hydrogen plasma in the temperature range of 10⁴–10⁵ K. The formulae presented here can be readily incorporated into time-dependent cooling models as well as collisional ionization equilibrium models.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"21 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139096132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SDSS-IV from 2014 to 2016: A Detailed Demographic Comparison over Three Years","authors":"Amy M. Jones, Rachael L. Beaton, Brian A. Cherinka, Karen L. Masters, Sara Lucatello, Aleksandar M. Diamond-Stanic, Sarah A. Bird, Michael R. Blanton, Katia Cunha, Emily E. Farr, Diane Feuillet, Peter M. Frinchaboy, Alex Hagen, Karen Kinemuchi, Britt Lundgren, Mariarosa L. Marinelli, Adam D. Myers, Alexandre Roman-Lopes, Ashley J. Ross, José R. Sánchez-Gallego, Sarah J. Schmidt, Jennifer Sobeck, Keivan G. Stassun, Jamie Tayar, Mariana Vargas-Magaña, J. C. Wilson, Gail Zasowski","doi":"10.1088/1538-3873/ad0d7b","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0d7b","url":null,"abstract":"The Sloan Digital Sky Survey (SDSS) is one of the largest international astronomy organizations. We present demographic data based on surveys of its members from 2014, 2015 and 2016, during the fourth phase of SDSS (SDSS-IV). We find about half of SDSS-IV collaboration members were based in North America, a quarter in Europe, and the remainder in Asia and Central and South America. Overall, 26%–36% are women (from 2014 to 2016), up to 2% report non-binary genders. 11%–14% report that they are racial or ethnic minorities where they live. The fraction of women drops with seniority, and is also lower among collaboration leadership. Men in SDSS-IV were more likely to report being in a leadership role, and for the role to be funded and formally recognized. SDSS-IV collaboration members are twice as likely to have a parent with a college degree, than the general population, and are ten times more likely to have a parent with a PhD. This trend is slightly enhanced for female collaboration members. Despite this, the fraction of first generation college students is significant (31%). This fraction increased among collaboration members who are racial or ethnic minorities (40%–50%), and decreased among women (15%–25%). SDSS-IV implemented many inclusive policies and established a dedicated committee, the Committee on INclusiveness in SDSS. More than 60% of the collaboration agree that the collaboration is inclusive; however, collaboration leadership more strongly agree with this than the general membership. In this paper, we explain these results in full, including the history of inclusive efforts in SDSS-IV. We conclude with a list of suggested recommendations based on our findings, which can be used to improve equity and inclusion in large astronomical collaborations, which we argue is not only moral, but will also optimize their scientific output.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"21 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Large Array Survey Telescope—Pipeline. I. Basic Image Reduction and Visit Coaddition","authors":"E. O. Ofek, Y. Shvartzvald, A. Sharon, C. Tishler, D. Elhanati, N. Segev, S. Ben-Ami, G. Nir, E. Segre, Y. Sofer-Rimalt, A. Blumenzweig, N. L. Strotjohann, D. Polishook, A. Krassilchtchikov, A. Zenin, V. Fallah Ramazani, S. Weimann, S. Garrappa, Y. Shanni, P. Chen, E. Zimmerman","doi":"10.1088/1538-3873/ad0977","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0977","url":null,"abstract":"The Large Array Survey Telescope (LAST) is a wide-field telescope designed to explore the variable and transient sky with a high cadence and to be a test-bed for cost-effective telescope design. A LAST node is composed of 48 (32 already deployed), 28 cm <italic toggle=\"yes\">f</italic>/2.2 telescopes. A single telescope has a 7.4 deg² field of view and reaches a 5<italic toggle=\"yes\">σ</italic> limiting magnitude of 19.6 (21.0) in 20 (20 × 20) s (filter-less), while the entire system provides a 355 deg² field of view. The basic strategy of LAST is to obtain multiple 20 s consecutive exposures of each field (a visit). Each telescope carries a 61 Mpix camera, and the system produces, on average, about 2.2 Gbit s⁻¹. This high data rate is analyzed in near real-time at the observatory site, using limited computing resources (about 700 cores). Given this high data rate, we have developed a new, efficient data reduction and analysis pipeline. The LAST data pipeline includes two major parts: (i) Processing and calibration of single images, followed by a coaddition of the visit’s exposures. (ii) Building the reference images and performing image subtraction and transient detection. Here we describe in detail the first part of the pipeline. Among the products of this pipeline are photometrically and astrometrically calibrated single and coadded images, 32 bit mask images marking a wide variety of problems and states of each pixel, source catalogs built from individual and coadded images, Point-Spread Function photometry, merged source catalogs, proper motion and variability indicators, minor planets detection, calibrated light curves, and matching with external catalogs. The entire pipeline code is made public. Finally, we demonstrate the pipeline performance on real data taken by LAST.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"80 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AstroSer: Leveraging Deep Learning for Efficient Content-based Retrieval in Massive Solar-observation Images","authors":"Shichao Wu, Yingbo Liu, Lei Yang, Xiaoying Liu, Xingxu Li, Yongyuan Xiang, Yunyu Gong","doi":"10.1088/1538-3873/ad0e7e","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0e7e","url":null,"abstract":"Rapid and proficient data retrieval is an essential component of modern astronomical research. In this paper, we address the challenge of retrieving astronomical image content by leveraging state-of-the-art deep learning techniques. We have designed a retrieval model, HybridVR, that integrates the capabilities of the deep learning models ResNet50 and VGG16 and have used it to extract key features of solar activity and solar environmental characteristics from observed images. This model enables efficient image matching and allows for content-based image retrieval (CBIR). Experimental results demonstrate that the model can achieve up to 98% similarity during CBIR while exhibiting adaptability and scalability. Our work has implications for astronomical research, data management, and education, and it can contribute to optimizing the utilization of astronomical image data. It also serves as a useful example of the application of deep learning technology in the field of astronomy.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138684285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Impact of Serpentinization on the Initial Conditions of Satellite Forming Collisions of Large Kuiper Belt Objects","authors":"A. Farkas-Takács, Csaba Kiss","doi":"10.1088/1538-3873/ad0f9a","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0f9a","url":null,"abstract":"Kuiper Belt objects are thought to be formed at least a few million years after the formation of calcium–aluminum-rich inclusions (CAIs), at a time when the 26Al isotope—the major source of radiogenic heat in the early solar system—had significantly depleted. The internal structure of these objects is highly dependent on any additional source that can produce extra heat in addition to that produced by the remaining, long-lasting radioactive isotopes. In this paper, we explore how serpentinization, the hydration of silicate minerals, can contribute to the heat budget and to what extent it can modify the internal structure of large Kuiper Belt objects. We find that the extent of restructuring depends very strongly on the start time of the formation process, the size of the object, and the starting ice-to-rock ratio. Serpentinization is able to restructure most of the interior of all objects in the whole size range (400–1200 km) and ice-to-rock ratio range investigated if the process starts early, ∼3 Myr after CAI formation, potentially leading to a predominantly serpentine core much earlier than previously thought (≤5 Myr versus several tens of million years). While the ratio of serpentinized material gradually decreases with the increasing formation time, the increasing ice-to-rock ratio, and the increasing start time of planetesimal formation in the outer solar system, in the case of the largest objects a significant part of the interior will be serpentinized even if the formation starts relatively late, ∼5 Myr after CAI formation. Therefore it is feasible that the interior of planetesimals may have contained a significant amount of serpentine, and in some cases, it could have been a dominant constituent, at the time of satellite-forming impacts.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"41 46","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138588727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Staring at the Sun with the Keck Planet Finder: An Autonomous Solar Calibrator for High Signal-to-noise Sun-as-a-star Spectra","authors":"Ryan A. Rubenzahl, Samuel Halverson, Josh Walawender, Grant M. Hill, Andrew W. Howard, Matthew Brown, Evan Ida, Jerez Tehero, Benjamin J. Fulton, Steven R. Gibson, Marc Kassis, Brett Smith, Truman Wold, Joel Payne","doi":"10.1088/1538-3873/ad0b30","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0b30","url":null,"abstract":"Extreme precision radial velocity (EPRV) measurements contend with internal noise (instrumental systematics) and external noise (intrinsic stellar variability) on the road to 10 cm s⁻¹ “exo-Earth” sensitivity. Both of these noise sources are well-probed using “Sun-as-a-star” RVs and cross-instrument comparisons. We built the Solar Calibrator (SoCal), an autonomous system that feeds stable, disk-integrated sunlight to the recently commissioned Keck Planet Finder (KPF) at the W. M. Keck Observatory. With SoCal, KPF acquires signal-to-noise ratio (S/N) ∼ 1200, <italic toggle=\"yes\">R</italic> = 98,000 optical (445–870 nm) spectra of the Sun in 5 s exposures at unprecedented cadence for an EPRV facility using KPF’s fast readout mode (&lt;16 s between exposures). Daily autonomous operation is achieved by defining an operations loop using state machine logic. Data affected by clouds are automatically flagged using a reliable quality control metric derived from simultaneous irradiance measurements. Comparing solar data across the growing global network of EPRV spectrographs with solar feeds will allow EPRV teams to disentangle internal and external noise sources and benchmark spectrograph performance. To facilitate this, all SoCal data products are immediately available to the public on the Keck Observatory Archive. We compared SoCal RVs to contemporaneous RVs from NEID, the only other immediately public EPRV solar data set. We find agreement at the 30–40 cm s⁻¹ level on timescales of several hours, which is comparable to the combined photon-limited precision. Data from SoCal were also used to assess a detector problem and wavelength calibration inaccuracies associated with KPF during early operations. Long-term SoCal operations will collect upwards of 1000 solar spectra per six-hour day using KPF’s fast readout mode, enabling stellar activity studies at high S/N on our nearest solar-type star.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"51 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138684481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Abrupt Resumptions of Pulsations in α Cygni (Deneb)","authors":"H. Abt, J. Guzik, J. Jackiewicz","doi":"10.1088/1538-3873/ad1118","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1118","url":null,"abstract":"Paddock’s 1927–1935 radial velocities of α Cygni (Deneb) show semi-regular pulsations with a dominant period of about 12 days. Lucy found many periods of lesser amplitude. In Paddock’s data and subsequent 1956 data from Abt, after the large-amplitude pulsations seemed to damp down, abruptly new sets of pulsations started within a fraction of a day. Five of those resumptions occurred with intervals averaging 72.4 ± 0.3 days. These resumptions seem to start at any phase during the pulsations. We are unaware of this behavior in any other star. We also find evidence of this behavior in the 1977–1982 radial velocity data of Parthasarathy & Lambert and the 1997–2001 photometry/radial velocity data of Richardson et al., as well as in photometric data from the NASA Transiting Exoplanet Survey Satellite (TESS) spacecraft and ground-based visual observations in the AAVSO International Database. The ground-based data have too infrequent sampling intervals to confirm the ∼70-day resumption intervals or to pinpoint the day and phase of abrupt amplitude increase. The TESS data, with 2-minute cadence, shows one instance of pulsation resumption, but does not have a long enough time series to confirm a 70-day interval. Without any evidence for duplicity, we cannot explain this behavior as being due to a companion in a highly eccentric orbit. α Cygni is one of the Luminous Blue Variables (supergiants) and these resumptions may be related to the microvariations produced in convective layers below their atmospheres, pulsation-driven shocks and rarefactions, or pulsation-convection interactions. We encourage further observations by ground-based observers and using the TESS spacecraft to confirm the ∼70-day resumption interval and lack of correlation with pulsation phase in both radial velocity and light curve data.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"65 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138993791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Proof of Concept Balanced Mixer with the use of a Digital IF Power Combiner to Improve LO Noise Rejection","authors":"D. Monasterio, Sebastian Jorquera, F. Curotto, Camilo Espinoza, R. Finger, L. Bronfman","doi":"10.1088/1538-3873/ad0789","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0789","url":null,"abstract":"In this work we present a novel digital technique, that allows local oscillator (LO) noise cancellation using a digital power combiner in a balanced mixer receiver architecture. A theoretical analysis of the noise cancellation using the proposed technique is derived and a proof of concept experiment is made for the Ku-Band. This experiment includes the design and construction of a custom balanced mixer and an artificial noise source. Experimental results show a consistent noise temperature reduction in comparison with a full analog mixer, and in some cases reaching noise temperature levels similar to the receiver operating without the artificial LO noise.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":" 5","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138615499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photometry, Centroid and Point-spread Function Measurements in the LSST Camera Focal Plane Using Artificial Stars","authors":"Johnny H. Esteves, Yousuke Utsumi, Adam Snyder, Theo Schutt, Alex Broughton, Bahrudin Trbalic, Sidney Mau, Andrew Rasmussen, Andrés A. Plazas Malagón, Andrew Bradshaw, Stuart Marshall, Seth Digel, James Chiang, Eli Rykoff, Chris Waters, Marcelle Soares-Santos, Aaron Roodman","doi":"10.1088/1538-3873/ad0a73","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0a73","url":null,"abstract":"The Vera C. Rubin Observatory’s LSST Camera (LSSTCam) pixel response has been characterized using laboratory measurements with a grid of artificial stars. We quantify the contributions to photometry, centroid, point-spread function size, and shape measurement errors due to small anomalies in the LSSTCam CCDs. The main sources of those anomalies are quantum efficiency variations and pixel area variations induced by the amplifier segmentation boundaries and “tree-rings”—circular variations in silicon doping concentration. This laboratory study using artificial stars projected on the sensors shows overall small effects. The residual effects on point-spread function (PSF) size and shape are below 0.1%, meeting the ten-year LSST survey science requirements. However, the CCD mid-line presents distortions that can have a moderate impact on PSF measurements. This feature can be avoided by masking the affected regions. Effects of tree-rings are observed on centroids and PSFs of the artificial stars and the nature of the effect is confirmed by a study of the flat-field response. Nevertheless, further studies of the full-focal plane with stellar data should more completely probe variations and might reveal new features, e.g., wavelength-dependent effects. The results of this study can be used as a guide for the on-sky operation of LSSTCam.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"28 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138684133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotational Phase Dependent J − H Colour of the Dwarf Planet Eris","authors":"R. Szakáts, Csaba Kiss","doi":"10.1088/1538-3873/ad0b31","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0b31","url":null,"abstract":"The largest bodies—or dwarf planets—constitute a different class among Kuiper Belt objects and are characterized by bright surfaces and volatile compositions remarkably different from that of smaller trans-Neptunian objects. These compositional differences are also reflected in the visible and near-infrared colors, and variegations across the surface can cause broadband colors to vary with rotational phase. Here we present near-infrared J and H-band observations of the dwarf planet (136199) Eris obtained with the GuideDog camera of the Infrared Telescope Facility. These measurements show that—as suspected from previous J − H measurements—the J − H color of Eris indeed varies with rotational phase. This suggests notable surface heterogenity in chemical composition and/or other material properties despite the otherwise quite homogeneous, high albedo surface, characterized by a very low amplitude visible range light curve. While variations in the grain size of the dominant CH4 may in general be responsible for notable changes in the J − H color, in the current observing geometry of the system it can only partially explain the observed J − H variation.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":" 606","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138610794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}