Pub Date : 2024-09-11DOI: 10.1088/1538-3873/ad7405
Daniel Majaess, David G. Turner, Dante Minniti, Javier Alonso-Garcia and Roberto K. Saito
The classical Cepheid KQ Sco is a valuable anchor for the distance scale because of its long pulsation period (28.ͩ7) and evidence implying membership in the open cluster UBC 1558. Analyses tied to Gaia DR3 astrometry, photometry, spectroscopy, radial velocities, and 2MASS-VVV photometry indicate a common distance of 2.15 ± 0.15 kpc (L21 DR3 corrections applied). Additional cluster Cepheid candidates requiring follow-up are identified, and it is suggested that a team of international researchers could maintain a cluster Cepheid database to guide the broader community to cases where consensus exists.
{"title":"The Valuable Long-period Cluster Cepheid KQ Scorpii and other Calibration Candidates","authors":"Daniel Majaess, David G. Turner, Dante Minniti, Javier Alonso-Garcia and Roberto K. Saito","doi":"10.1088/1538-3873/ad7405","DOIUrl":"https://doi.org/10.1088/1538-3873/ad7405","url":null,"abstract":"The classical Cepheid KQ Sco is a valuable anchor for the distance scale because of its long pulsation period (28.ͩ7) and evidence implying membership in the open cluster UBC 1558. Analyses tied to Gaia DR3 astrometry, photometry, spectroscopy, radial velocities, and 2MASS-VVV photometry indicate a common distance of 2.15 ± 0.15 kpc (L21 DR3 corrections applied). Additional cluster Cepheid candidates requiring follow-up are identified, and it is suggested that a team of international researchers could maintain a cluster Cepheid database to guide the broader community to cases where consensus exists.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183180","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}
Pub Date : 2024-09-10DOI: 10.1088/1538-3873/ad70d7
Kylie E. Hall, Jennifer C. Yee, In-Gu Shin, Hongjing Yang and Jiyuan Zhang
The gravitational microlensing method of discovering exoplanets and multi-star systems can produce degenerate solutions, some of which require in-depth analysis to uncover. We propose a new parameter space that can be used to sample potential solutions more efficiently and is more robust at finding all degenerate solutions for the “central-resonant” caustic degeneracy. We identified two new parameters, k and h, that can be sampled in place of the mass ratios and separations of the systems under analysis to identify degenerate solutions. The parameter k is related to the size of the central caustic, Δξc, while h is related to the distance of a point along the k contour from log(s) = 0, where s is the projected planet-host separation. In this work, we present the characteristics of these parameters and the tests we conducted to prove their efficacy.
发现系外行星和多恒星系统的引力微透镜方法会产生退化解，其中一些需要深入分析才能发现。我们提出了一个新的参数空间，可用于更有效地对潜在解进行采样，并能更稳健地找到 "中心共振 "苛性退化的所有退化解。我们确定了两个新参数 k 和 h，它们可以代替被分析系统的质量比和分离度来确定退化解。参数k与中心苛性的大小Δξc有关，而h则与沿k等值线的点与log(s) = 0的距离有关，其中s是投影的行星-宿主分离度。在这项工作中，我们介绍了这些参数的特点，以及为证明其有效性而进行的测试。
{"title":"A New Parameterization for Finding Solutions for Microlensing Exoplanet Light Curves","authors":"Kylie E. Hall, Jennifer C. Yee, In-Gu Shin, Hongjing Yang and Jiyuan Zhang","doi":"10.1088/1538-3873/ad70d7","DOIUrl":"https://doi.org/10.1088/1538-3873/ad70d7","url":null,"abstract":"The gravitational microlensing method of discovering exoplanets and multi-star systems can produce degenerate solutions, some of which require in-depth analysis to uncover. We propose a new parameter space that can be used to sample potential solutions more efficiently and is more robust at finding all degenerate solutions for the “central-resonant” caustic degeneracy. We identified two new parameters, k and h, that can be sampled in place of the mass ratios and separations of the systems under analysis to identify degenerate solutions. The parameter k is related to the size of the central caustic, Δξc, while h is related to the distance of a point along the k contour from log(s) = 0, where s is the projected planet-host separation. In this work, we present the characteristics of these parameters and the tests we conducted to prove their efficacy.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183192","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}
Pub Date : 2024-09-06DOI: 10.1088/1538-3873/ad716c
Kenneth W. Lin, Armin Karcher, Julien Guy, Stephen E. Holland, William F. Kolbe, Peter E. Nugent, Alex Drlica-Wagner, Ana M. Botti, Javier Tiffenberg
We present characterization results and performance of a prototype Multiple-Amplifier Sensing (MAS) silicon charge-coupled device (CCD) sensor with 16 channels potentially suitable for faint object astronomical spectroscopy and low-signal, photon-limited imaging. The MAS CCD is designed to reach sub-electron readout noise by repeatedly measuring charge through a line of amplifiers during the serial transfer shifts. Using synchronized readout electronics based on the Dark Energy Spectroscopic Instrument CCD controller, we report a read noise of 1.03 e− rms pix−1 at a speed of 26 μs pix−1 with a single-sample readout scheme where charge in a pixel is measured only once for each output stage. At these operating parameters, we find the amplifier-to-amplifier charge transfer efficiency (ACTE) to be >0.9995 at low counts for all amplifiers but one for which the ACTE is 0.997. This charge transfer efficiency falls above 50,000 electrons for the read-noise optimized voltage configuration we chose for the serial clocks and gates. The amplifier linearity across a broad dynamic range from ∼300 to 35,000 e− was also measured to be ±2.5%. We describe key operating parameters to optimize on these characteristics and describe the specific applications for which the MAS CCD may be a suitable detector candidate.
{"title":"Multi-amplifier Sensing Charge-coupled Devices for Next Generation Spectroscopy","authors":"Kenneth W. Lin, Armin Karcher, Julien Guy, Stephen E. Holland, William F. Kolbe, Peter E. Nugent, Alex Drlica-Wagner, Ana M. Botti, Javier Tiffenberg","doi":"10.1088/1538-3873/ad716c","DOIUrl":"https://doi.org/10.1088/1538-3873/ad716c","url":null,"abstract":"We present characterization results and performance of a prototype Multiple-Amplifier Sensing (MAS) silicon charge-coupled device (CCD) sensor with 16 channels potentially suitable for faint object astronomical spectroscopy and low-signal, photon-limited imaging. The MAS CCD is designed to reach sub-electron readout noise by repeatedly measuring charge through a line of amplifiers during the serial transfer shifts. Using synchronized readout electronics based on the Dark Energy Spectroscopic Instrument CCD controller, we report a read noise of 1.03 e<sup>−</sup> rms pix<sup>−1</sup> at a speed of 26 <italic toggle=\"yes\">μ</italic>s pix<sup>−1</sup> with a single-sample readout scheme where charge in a pixel is measured only once for each output stage. At these operating parameters, we find the amplifier-to-amplifier charge transfer efficiency (ACTE) to be >0.9995 at low counts for all amplifiers but one for which the ACTE is 0.997. This charge transfer efficiency falls above 50,000 electrons for the read-noise optimized voltage configuration we chose for the serial clocks and gates. The amplifier linearity across a broad dynamic range from ∼300 to 35,000 e<sup>−</sup> was also measured to be ±2.5%. We describe key operating parameters to optimize on these characteristics and describe the specific applications for which the MAS CCD may be a suitable detector candidate.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183181","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}
Pub Date : 2024-09-03DOI: 10.1088/1538-3873/ad6f44
J. W. Zhou, Pavel Kroupa, Sami Dib
Using the optimal sampling model, we synthesized the embedded clusters of ATLASGAL clumps with H ii regions (H ii-clumps). The 0.1 Myr isochrone was used to estimate the bolometric luminosity of each star in an embedded cluster, we also added the accretion luminosity of each star in the embedded cluster. The total bolometric luminosity of synthetic embedded clusters can well fit the observed bolometric luminosity of H ii-clumps. More realistically, we considered the age spread in the young star and protostar populations in embedded clusters of H ii-clumps by modeling both constant and time-varying star formation histories (SFHs). According to the age distribution of the stellar population, we distributed the appropriate isochrones to each star, and sorted out the fraction of stellar objects that are still protostars (Class 0 and Class I phases) to properly add their accretion luminosities. Compared to a constant SFH, burst-like and time-dependent SFHs can better fit the observational data. We found that as long as 20% of the stars within the embedded cluster are still accreting, the contribution of accretion luminosity will be significant to the total bolometric luminosity of low-mass H ii-clumps with mass log10(Mcl/M⊙) < 2.8. Variations in the accretion rate, the SFE and the initial mass function and more physical processes like the external heating from H ii regions and the flaring from pre-main sequence stars and protostars need to be investigated to further explain the excess luminosity of low-mass H ii-clumps.
利用最优采样模型，我们合成了带有H ii区域的ATLASGAL星团的嵌入星团（H i-clumps）。我们用0.1 Myr等时区来估算嵌入星团中每颗恒星的测光度，并加上嵌入星团中每颗恒星的吸积光度。合成嵌入星团的总测光度可以很好地拟合观测到的 H ii-clumps 的测光度。更为现实的是，我们通过模拟恒星形成史（SFH）和时变恒星形成史（SFH），考虑了 H ii-clumps 嵌入星团中年轻恒星和原恒星群的年龄分布。根据恒星群的年龄分布，我们为每颗恒星分配了适当的等时线，并对仍属于原恒星（0级和I级阶段）的恒星天体进行了分类，以适当增加它们的吸积光度。与恒定的SFH相比，类似爆发和随时间变化的SFH更适合观测数据。我们发现，只要嵌入星团中仍有20%的恒星在吸积，吸积光度对质量为log10(Mcl/M⊙) < 2.8的低质量H i-星团的总测光度的贡献就会很大。吸积率、SFE和初始质量函数的变化，以及更多的物理过程，如来自H ii区域的外部加热和来自前主序星和原恒星的闪烁，都需要进行研究，以进一步解释低质量H i-团块的过量光度。
{"title":"Physical Properties of Embedded Clusters in ATLASGAL Clumps with H ii Regions","authors":"J. W. Zhou, Pavel Kroupa, Sami Dib","doi":"10.1088/1538-3873/ad6f44","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6f44","url":null,"abstract":"Using the optimal sampling model, we synthesized the embedded clusters of ATLASGAL clumps with H<sc> ii</sc> regions (H<sc> ii</sc>-clumps). The 0.1 Myr isochrone was used to estimate the bolometric luminosity of each star in an embedded cluster, we also added the accretion luminosity of each star in the embedded cluster. The total bolometric luminosity of synthetic embedded clusters can well fit the observed bolometric luminosity of H<sc> ii</sc>-clumps. More realistically, we considered the age spread in the young star and protostar populations in embedded clusters of H<sc> ii</sc>-clumps by modeling both constant and time-varying star formation histories (SFHs). According to the age distribution of the stellar population, we distributed the appropriate isochrones to each star, and sorted out the fraction of stellar objects that are still protostars (Class 0 and Class I phases) to properly add their accretion luminosities. Compared to a constant SFH, burst-like and time-dependent SFHs can better fit the observational data. We found that as long as 20% of the stars within the embedded cluster are still accreting, the contribution of accretion luminosity will be significant to the total bolometric luminosity of low-mass H<sc> ii</sc>-clumps with mass log<sub>10</sub>(<italic toggle=\"yes\">M</italic>\u0000<sub>cl</sub>/<italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub>) < 2.8. Variations in the accretion rate, the SFE and the initial mass function and more physical processes like the external heating from H<sc> ii</sc> regions and the flaring from pre-main sequence stars and protostars need to be investigated to further explain the excess luminosity of low-mass H<sc> ii</sc>-clumps.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183183","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}
Pub Date : 2024-09-03DOI: 10.1088/1538-3873/ad6f45
J. R. Sauter, W. Brandner, J. Heidt, F. Cantalloube
Ground-based thermal infrared observations face substantial challenges in correcting the predominant background emitted as thermal radiation from the atmosphere and the telescope itself. With the upcoming 40 m class ELTs, unprecedented sensitivities from ground will be reached, underlining the need of even more sophisticated background correction strategies. This study aims to investigate the impact of thermal backgrounds on ground-based observations and identify possible limiting factors in dedicated correction strategies. We evaluate temporal and spatial characteristics of the thermal background in direct imaging data obtained with different telescopes and observation modes. In particular, three distinct data sets, acquired using VLT/NACO and KECK/NIRC2, are analyzed. Our analysis reveals that the observations are not fully photon shot noise limited, but exhibit additional sensitivity losses caused by imperfect background compensation in the different data sets. We identify correlations between background fluctuations and the activity of the adaptive optics system. We hypothesize that the pupil modulation of the adaptive optics mirrors introduces high frequency spatial and temporal fluctuations to the background, which could ultimately constrain the detection limit if they are not compensated adequately.
{"title":"Detection Limits of Thermal-infrared Observations with Adaptive Optics. I. Observational Data","authors":"J. R. Sauter, W. Brandner, J. Heidt, F. Cantalloube","doi":"10.1088/1538-3873/ad6f45","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6f45","url":null,"abstract":"Ground-based thermal infrared observations face substantial challenges in correcting the predominant background emitted as thermal radiation from the atmosphere and the telescope itself. With the upcoming 40 m class ELTs, unprecedented sensitivities from ground will be reached, underlining the need of even more sophisticated background correction strategies. This study aims to investigate the impact of thermal backgrounds on ground-based observations and identify possible limiting factors in dedicated correction strategies. We evaluate temporal and spatial characteristics of the thermal background in direct imaging data obtained with different telescopes and observation modes. In particular, three distinct data sets, acquired using VLT/NACO and KECK/NIRC2, are analyzed. Our analysis reveals that the observations are not fully photon shot noise limited, but exhibit additional sensitivity losses caused by imperfect background compensation in the different data sets. We identify correlations between background fluctuations and the activity of the adaptive optics system. We hypothesize that the pupil modulation of the adaptive optics mirrors introduces high frequency spatial and temporal fluctuations to the background, which could ultimately constrain the detection limit if they are not compensated adequately.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183184","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}
Pub Date : 2024-09-03DOI: 10.1088/1538-3873/ad6e18
Zsófia Bora, Réka Könyves-Tóth, József Vinkó, Dominik Bánhidi, Imre Barna Bíró, K. Azalee Bostroem, Attila Bódi, Jamison Burke, István Csányi, Borbála Cseh, Joseph Farah, Alexei V. Filippenko, Tibor Hegedüs, Daichi Hiramatsu, Ágoston Horti-Dávid, D. Andrew Howell, Saurabh W. Jha, Csilla Kalup, Máté Krezinger, Levente Kriskovics, Curtis McCully, Megan Newsome, András Ordasi, Estefania Padilla Gonzalez, András Pál, Craig Pellegrino, Bálint Seli, Ádám Sódor, Zsófia Marianna Szabó, Olivér Norton Szabó, Róbert Szakáts, Tamás Szalai, Péter Székely, Giacomo Terreran, Vázsony Varga, Krisztián Vida, Xiaofeng Wang, J. Craig Wheeler
The progenitor system(s) as well as the explosion mechanism(s) of thermonuclear (Type Ia) supernovae are long-standing issues in astrophysics. Here we present ejecta masses and other physical parameters for 28 recent Type Ia supernovae inferred from multiband photometric and optical spectroscopic data. Our results confirm that the majority of SNe Ia show observable ejecta masses below the Chandrasekhar-limit (having a mean Mej ≈ 1.1 ± 0.3 M⊙), consistent with the predictions of recent sub-MCh explosion models. They are compatible with models assuming either single- or double-degenerate progenitor configurations. We also recover a sub-sample of supernovae within 1.2 M⊙ < Mej < 1.5 M⊙ that are consistent with near-Chandrasekhar explosions. Taking into account the uncertainties of the inferred ejecta masses, about half of our SNe are compatible with both explosion models. We compare our results with those in previous studies, and discuss the caveats and concerns regarding the applied methodology.
{"title":"Ejecta Masses in Type Ia Supernovae—Implications for the Progenitor and the Explosion Scenario* * Based in part on observations obtained with the Hobby-Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximillians-Universitaet Muenchen, and Georg-August Universitaet Goettingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.","authors":"Zsófia Bora, Réka Könyves-Tóth, József Vinkó, Dominik Bánhidi, Imre Barna Bíró, K. Azalee Bostroem, Attila Bódi, Jamison Burke, István Csányi, Borbála Cseh, Joseph Farah, Alexei V. Filippenko, Tibor Hegedüs, Daichi Hiramatsu, Ágoston Horti-Dávid, D. Andrew Howell, Saurabh W. Jha, Csilla Kalup, Máté Krezinger, Levente Kriskovics, Curtis McCully, Megan Newsome, András Ordasi, Estefania Padilla Gonzalez, András Pál, Craig Pellegrino, Bálint Seli, Ádám Sódor, Zsófia Marianna Szabó, Olivér Norton Szabó, Róbert Szakáts, Tamás Szalai, Péter Székely, Giacomo Terreran, Vázsony Varga, Krisztián Vida, Xiaofeng Wang, J. Craig Wheeler","doi":"10.1088/1538-3873/ad6e18","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6e18","url":null,"abstract":"The progenitor system(s) as well as the explosion mechanism(s) of thermonuclear (Type Ia) supernovae are long-standing issues in astrophysics. Here we present ejecta masses and other physical parameters for 28 recent Type Ia supernovae inferred from multiband photometric and optical spectroscopic data. Our results confirm that the majority of SNe Ia show <italic toggle=\"yes\">observable</italic> ejecta masses below the Chandrasekhar-limit (having a mean <italic toggle=\"yes\">M</italic>\u0000<sub>ej</sub> ≈ 1.1 ± 0.3 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub>), consistent with the predictions of recent sub-<italic toggle=\"yes\">M</italic>\u0000<sub>Ch</sub> explosion models. They are compatible with models assuming either single- or double-degenerate progenitor configurations. We also recover a sub-sample of supernovae within 1.2 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub> < <italic toggle=\"yes\">M</italic>\u0000<sub>ej</sub> < 1.5 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub> that are consistent with near-Chandrasekhar explosions. Taking into account the uncertainties of the inferred ejecta masses, about half of our SNe are compatible with both explosion models. We compare our results with those in previous studies, and discuss the caveats and concerns regarding the applied methodology.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183182","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}
Pub Date : 2024-08-30DOI: 10.1088/1538-3873/ad6cf2
Sanaz Vahidinia, Sarah E. Moran, Mark S. Marley, Jeffrey N. Cuzzi
Aerosol opacity has emerged as a critical factor controlling transmission and emission spectra. We provide a simple guideline for the effects of aerosol morphology on opacity and residence time in the atmosphere, as it pertains to transit observations, particularly those with flat spectra due to high altitude aerosols. This framework can be used for understanding complex cloud and haze particle properties before getting into detailed microphysical modeling. We consider high altitude aerosols to be composed of large fluffy particles that can have large residence times in the atmosphere and influence the deposition of stellar flux and/or the emergence of thermal emission in a different way than compact droplet particles, as generally modeled to date for extrasolar planetary atmospheres. We demonstrate the important influence of aggregate particle porosity and composition on the extent of the wavelength independent regime. We also consider how such fluffy particles reach such high altitudes and conclude that the most likely scenario is their local production at high altitudes via UV bombardment and subsequent blanketing of the atmosphere, rather than some mechanism of lofting or transport from the lower atmosphere.
{"title":"Aggregate Cloud Particle Effects in Exoplanet Atmospheres","authors":"Sanaz Vahidinia, Sarah E. Moran, Mark S. Marley, Jeffrey N. Cuzzi","doi":"10.1088/1538-3873/ad6cf2","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6cf2","url":null,"abstract":"Aerosol opacity has emerged as a critical factor controlling transmission and emission spectra. We provide a simple guideline for the effects of aerosol morphology on opacity and residence time in the atmosphere, as it pertains to transit observations, particularly those with flat spectra due to high altitude aerosols. This framework can be used for understanding complex cloud and haze particle properties before getting into detailed microphysical modeling. We consider high altitude aerosols to be composed of large fluffy particles that can have large residence times in the atmosphere and influence the deposition of stellar flux and/or the emergence of thermal emission in a different way than compact droplet particles, as generally modeled to date for extrasolar planetary atmospheres. We demonstrate the important influence of aggregate particle porosity and composition on the extent of the wavelength independent regime. We also consider how such fluffy particles reach such high altitudes and conclude that the most likely scenario is their local production at high altitudes via UV bombardment and subsequent blanketing of the atmosphere, rather than some mechanism of lofting or transport from the lower atmosphere.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183185","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}
Pub Date : 2024-08-28DOI: 10.1088/1538-3873/ad6bc1
Li-Wei Hung, Jeremy White, Damon Joyce, Sharolyn J Anderson, Benjamin Banet
The Night Skies Team of the U.S. National Park Service (NPS) has developed a new camera system equipped with a fisheye lens to measure night sky brightness. This NPS Fisheye Night Sky Imager comprises a back-illuminated Sony IMX455 CMOS sensor housed in the ZWO ASI6200MM camera, a Johnson V filter, and a Sigma 8 mm F3.5 fisheye lens. All of the components are commercially available. The fisheye lens allows us to capture the entire sky in a single frame. The wide-angle view also introduces calibration challenges. To address this, we have customized tools and devised innovative methods for calibrating the system, including flat-field correction, pixel scale determination, and field of view characterization. Additionally, we use standard stars for precise positional and photometric calibration. Furthermore, we create an open-source Python pipeline to process these fisheye images and leverage Git and GitHub for source code version control and distribution. The resulting images provide a positionally and brightness-calibrated fisheye view of the night sky, with a photometric calibration uncertainty of 0.12 mag. When comparing our Fisheye Night Sky Imager measurements to images taken with other calibrated systems, we reliably achieve consistent results under both dark and bright skies. Our Fisheye Night Sky Imager not only enables rapid assessment of sky quality but also supports the feasibility of establishing permanent monitoring locations. Recognizing that the natural dark sky is a critical element for natural, cultural, educational, and visitor experiences, this new camera system enhances our ability to assess resource conditions and fulfill the NPS mission of conserving resources unimpaired for the enjoyment of this and future generations.
{"title":"Fisheye Night Sky Imager: A Calibrated Tool to Measure Night Sky Brightness","authors":"Li-Wei Hung, Jeremy White, Damon Joyce, Sharolyn J Anderson, Benjamin Banet","doi":"10.1088/1538-3873/ad6bc1","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6bc1","url":null,"abstract":"The Night Skies Team of the U.S. National Park Service (NPS) has developed a new camera system equipped with a fisheye lens to measure night sky brightness. This NPS Fisheye Night Sky Imager comprises a back-illuminated Sony IMX455 CMOS sensor housed in the ZWO ASI6200MM camera, a Johnson V filter, and a Sigma 8 mm F3.5 fisheye lens. All of the components are commercially available. The fisheye lens allows us to capture the entire sky in a single frame. The wide-angle view also introduces calibration challenges. To address this, we have customized tools and devised innovative methods for calibrating the system, including flat-field correction, pixel scale determination, and field of view characterization. Additionally, we use standard stars for precise positional and photometric calibration. Furthermore, we create an open-source Python pipeline to process these fisheye images and leverage Git and GitHub for source code version control and distribution. The resulting images provide a positionally and brightness-calibrated fisheye view of the night sky, with a photometric calibration uncertainty of 0.12 mag. When comparing our Fisheye Night Sky Imager measurements to images taken with other calibrated systems, we reliably achieve consistent results under both dark and bright skies. Our Fisheye Night Sky Imager not only enables rapid assessment of sky quality but also supports the feasibility of establishing permanent monitoring locations. Recognizing that the natural dark sky is a critical element for natural, cultural, educational, and visitor experiences, this new camera system enhances our ability to assess resource conditions and fulfill the NPS mission of conserving resources unimpaired for the enjoyment of this and future generations.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183186","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}
Pub Date : 2024-08-22DOI: 10.1088/1538-3873/ad6a8a
Xiu-Juan Li, Jia-Mu Liu, Ming Cheng, Yan-Na Wang, Wen-Long Zhang
In this work, we restudy the scale-invariant features of X-ray bursts from the soft gamma repeater (SGR) J1935+2154. To compare with previous studies, we choose 75 bursts from a dedicated 33 days-long observation carried out by Insight-HXMT. We investigate the size difference distributions of net counts, duration, and waiting time. It is found that the cumulative difference distributions of net counts and duration follow the q-Gaussian models with approximately steady q-values, confirming that the scale-invariant features exist in X-ray bursts of SGR J1935+2154. Regarding the varying results of waiting time reported by Sang & Lin and Wei et al, we find that the distributions of waiting time can be well described by the q-Gaussian model. Furthermore, the q-values of waiting time remain relatively stable at the 3σ confidence level, corroborating the scale invariance in the X-ray bursts. Additionally, we note that there is no significant q-value evolution across three Insight-HXMT telescopes. These findings statistically affirm that the X-ray bursts from SGR J1935+2154 can be attributed to an fractal-diffusive self-organized criticality system with a plausible Euclidean spatial dimension S = 3, implying that X-ray bursts from SGR J1935+2154 and associated astrophysical phenomena may share a similar magnetically dominated stochastic process.
在这项工作中，我们重新研究了来自软伽马中继器（SGR）J1935+2154 的 X 射线暴的尺度不变特征。为了与以前的研究进行比较，我们从 Insight-HXMT 进行的长达 33 天的专门观测中选择了 75 个脉冲串。我们研究了净计数、持续时间和等待时间的大小差异分布。结果发现，净计数和持续时间的累积差分布遵循q-高斯模型，q值近似稳定，这证实了SGR J1935+2154的X射线暴存在尺度不变的特征。关于Sang & Lin和Wei等人报告的等待时间的不同结果，我们发现q-高斯模型可以很好地描述等待时间的分布。此外，等待时间的q值在3σ置信水平下保持相对稳定，这证实了X射线暴的尺度不变性。此外，我们还注意到，Insight-HXMT 三台望远镜的 q 值没有明显的变化。这些发现从统计学上肯定了来自 SGR J1935+2154 的 X 射线暴可以归因于一个分形扩散自组织临界系统，其可信的欧几里得空间维度为 S = 3，这意味着来自 SGR J1935+2154 的 X 射线暴和相关的天体物理现象可能具有类似的磁主导随机过程。
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Pub Date : 2024-08-21DOI: 10.1088/1538-3873/ad5c9f
Joost P. Wardenier, Vivien Parmentier, Michael R. Line, Megan Weiner Mansfield, Xianyu Tan, Shang-Min Tsai, Jacob L. Bean, Jayne L. Birkby, Matteo Brogi, Jean-Michel Désert, Siddharth Gandhi, Elspeth K. H. Lee, Colette I. Levens, Lorenzo Pino, Peter C. B. Smith
Ultra-hot Jupiters (UHJs) are among the best targets for atmospheric characterization at high spectral resolution. Resolving their transmission spectra as a function of orbital phase offers a unique window into the 3D nature of these objects. In this work, we present three transits of the UHJ WASP-121b observed with Gemini-S/IGRINS. For the first time, we measure the phase-dependent absorption signals of CO and H2O in the atmosphere of an exoplanet, and we find that they are different. While the blueshift of CO increases during the transit, the absorption lines of H2O become less blueshifted with phase, and even show a redshift in the second half of the transit. These measurements reveal the distinct spatial distributions of both molecules across the atmospheres of UHJs. Also, we find that the H2O signal is absent in the first quarter of the transit, potentially hinting at cloud formation on the evening terminator of WASP-121b. To further interpret the absorption trails of CO and H2O, as well as the Doppler shifts of Fe previously measured with VLT/ESPRESSO, we compare the data to simulated transits of WASP-121b. To this end, we post-process the outputs of the global circulation models with a 3D Monte-Carlo radiative transfer code. Our analysis shows that the atmosphere of WASP-121b is subject to atmospheric drag, as previously suggested by small hotspot offsets inferred from phase-curve observations. Our study highlights the importance of phase-resolved spectroscopy in unravelling the complex atmospheric structure of UHJs and sets the stage for further investigations into their chemistry and dynamics.
超热木星（UHJs）是以高光谱分辨率进行大气特征描述的最佳目标之一。将它们的透射光谱作为轨道相位的函数进行解析，为了解这些天体的三维性质提供了一个独特的窗口。在这项工作中，我们展示了用 Gemini-S/IGRINS观测到的 UHJ WASP-121b 的三次凌日。我们首次测量了系外行星大气中 CO 和 H2O 随相位变化的吸收信号，发现它们是不同的。CO的蓝移在凌日过程中会增加，而H2O的吸收线则随着相位的变化而降低蓝移，甚至在凌日的后半段出现红移。这些测量结果揭示了这两种分子在 UHJ 大气层中的不同空间分布。此外，我们还发现，在凌日的前四分之一时间里，H2O 信号并不存在，这可能暗示了 WASP-121b 晚间终结者上云层的形成。为了进一步解释 CO 和 H2O 的吸收轨迹，以及之前用 VLT/ESPRESSO 测得的 Fe 的多普勒频移，我们将数据与 WASP-121b 的模拟凌日进行了比较。为此，我们使用三维蒙特卡洛辐射传递代码对全球环流模型的输出结果进行了后处理。我们的分析表明，WASP-121b 的大气受到了大气阻力的影响，这与之前从相位曲线观测中推断出的小热点偏移所显示的情况一样。我们的研究强调了相位分辨光谱在揭示超高强子复杂大气结构方面的重要性，并为进一步研究其化学和动力学奠定了基础。
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