Pub Date : 2024-02-20DOI: 10.1088/1538-3873/ad119f
Leo Kamgar, Kevin France, Allison Youngblood
The physical and chemical properties of planetary atmospheres are affected by temporal evolution of ultraviolet (UV) radiation inputs from their host stars at all time scales. While studies of X-ray/UV flare properties and long-term stellar evolution of exoplanet host stars have provided new constraints regarding stellar inputs to exoplanetary systems, the UV temporal variability of cool stars on the timescale of stellar cycles remains largely unexplored. To address this gap in our understanding of the UV temporal variability of cool stars, we analyze far-ultraviolet (FUV) emission lines of ions that trace the chromosphere and transition region of nearby stars (C <sc>ii</sc>, Si <sc>iii</sc>, Si <sc>iv</sc>, and N <sc>v</sc>; formation temperatures ∼ 20–150 kK) using data from the Hubble Space Telescope (HST) and International Ultraviolet Explorer (IUE) archives spanning temporal baselines of months to years. We select 33 unique stars of spectral types F-M with observing campaigns spanning over a year, and create ionic light curves to evaluate the characteristic variability of cool stars on such timescales. Screening for large flare events, we observe that the relative variability of FUV light curves decreases with increasing stellar effective temperature, from 30% to 70% variability for M-type stars to <30% variability for F and G-type stars. We also observe a weak trend in the temporal variability with the Ca <sc>ii</sc> <inline-formula> <tex-math> <?CDATA ${R}_{mathrm{HK}}^{{prime} }$?> </tex-math> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mi>R</mml:mi></mml:mrow><mml:mrow><mml:mi>HK</mml:mi></mml:mrow><mml:mrow><mml:mo accent="true">′</mml:mo></mml:mrow></mml:msubsup></mml:math> <inline-graphic xlink:href="paspad119fieqn1.gif" xlink:type="simple"></inline-graphic> </inline-formula> stellar activity indicator, suggesting that stars with lower Ca <sc>ii</sc> activity exhibit a smaller range of FUV flux variability. Screening for data sets with optimal temporal spread, and a sufficient number of individual observations, we select 5 data sets for further periodicity analysis (HST <italic toggle="yes">α</italic> Centauri A, HST <italic toggle="yes">α</italic> Centauri B, IUE <italic toggle="yes">α</italic> Centauri B, IUE <italic toggle="yes">ϵ</italic> Eri, IUE <italic toggle="yes">ξ</italic> Boo). Various periodic structures within the FUV flux were detected, with most significant being a 79 days frequency present within the IUE observations of <italic toggle="yes">ξ</italic> Boo, with a significance of 6<italic toggle="yes">σ</italic>, and a periodic signal in the FUV observations of <italic toggle="yes">α</italic> Centauri B, for both HST and IUE measurements, at ≈210 days frequency with significance of 3<italic toggle="yes">σ</italic> and 3.7<italic toggle="yes">σ</italic>, respectively. Our results suggest that extreme ultraviolet flux from cool stars varies by less than a factor of two on decade timescales, significantly sm
行星大气的物理和化学性质受到来自其宿主恒星的紫外线（UV）辐射输入在所有时间尺度上的时间演化的影响。虽然对系外行星宿主恒星的 X 射线/紫外线耀斑特性和长期恒星演化的研究为系外行星系统的恒星输入提供了新的约束条件，但在恒星周期的时间尺度上，冷恒星的紫外线时变性在很大程度上仍未得到探索。为了弥补我们对冷恒星紫外线时变性认识上的这一空白，我们利用哈勃太空望远镜（HST）和国际紫外线探测器（IUE）档案中的数据，分析了追踪附近恒星（C ii、Si iii、Si iv 和 N v；形成温度 ∼ 20-150 kK）色球层和过渡区的离子远紫外（FUV）发射线，其时间基线跨度从数月到数年不等。我们选择了 33 颗光谱类型为 F-M 的独特恒星，观测活动跨度超过一年，并绘制了离子光曲线，以评估冷恒星在这种时间尺度上的特征变异性。通过对大型耀斑事件的筛选，我们观察到 FUV 光曲线的相对可变性随着恒星有效温度的升高而降低，从 M 型恒星的 30% 到 70% 可变性到 F 型和 G 型恒星的 <30% 可变性。我们还观察到随着 Ca iiRHK′ 恒星活动性指标的变化，时间变率呈微弱趋势，这表明 Ca ii 活动性较低的恒星表现出的 FUV 通量变率范围较小。在筛选具有最佳时间分布和足够数量的单个观测数据集时，我们选择了 5 个数据集进行进一步的周期性分析（HST α 半人马座 A、HST α 半人马座 B、IUE α 半人马座 B、IUE ϵ Eri、IUE ξ Boo）。在 FUV 流量中探测到了各种周期性结构，其中最重要的是ξ Boo 的 IUE 观测中出现的频率为 79 天的周期信号，其显著性为 6σ；在半人马座α B 的 FUV 观测中，HST 和 IUE 的测量都出现了频率为≈210 天的周期信号，其显著性分别为 3σ 和 3.7σ。我们的结果表明，来自冷恒星的极端紫外通量在十年时间尺度上的变化不到2倍，明显小于耀斑或恒星演化时间尺度上的变化。
{"title":"Time Variability of FUV Emission from Cool Stars on Multi-year Timescales","authors":"Leo Kamgar, Kevin France, Allison Youngblood","doi":"10.1088/1538-3873/ad119f","DOIUrl":"https://doi.org/10.1088/1538-3873/ad119f","url":null,"abstract":"The physical and chemical properties of planetary atmospheres are affected by temporal evolution of ultraviolet (UV) radiation inputs from their host stars at all time scales. While studies of X-ray/UV flare properties and long-term stellar evolution of exoplanet host stars have provided new constraints regarding stellar inputs to exoplanetary systems, the UV temporal variability of cool stars on the timescale of stellar cycles remains largely unexplored. To address this gap in our understanding of the UV temporal variability of cool stars, we analyze far-ultraviolet (FUV) emission lines of ions that trace the chromosphere and transition region of nearby stars (C <sc>ii</sc>, Si <sc>iii</sc>, Si <sc>iv</sc>, and N <sc>v</sc>; formation temperatures ∼ 20–150 kK) using data from the Hubble Space Telescope (HST) and International Ultraviolet Explorer (IUE) archives spanning temporal baselines of months to years. We select 33 unique stars of spectral types F-M with observing campaigns spanning over a year, and create ionic light curves to evaluate the characteristic variability of cool stars on such timescales. Screening for large flare events, we observe that the relative variability of FUV light curves decreases with increasing stellar effective temperature, from 30% to 70% variability for M-type stars to <30% variability for F and G-type stars. We also observe a weak trend in the temporal variability with the Ca <sc>ii</sc>\u0000<inline-formula>\u0000<tex-math>\u0000<?CDATA ${R}_{mathrm{HK}}^{{prime} }$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mi>R</mml:mi></mml:mrow><mml:mrow><mml:mi>HK</mml:mi></mml:mrow><mml:mrow><mml:mo accent=\"true\">′</mml:mo></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"paspad119fieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> stellar activity indicator, suggesting that stars with lower Ca <sc>ii</sc> activity exhibit a smaller range of FUV flux variability. Screening for data sets with optimal temporal spread, and a sufficient number of individual observations, we select 5 data sets for further periodicity analysis (HST <italic toggle=\"yes\">α</italic> Centauri A, HST <italic toggle=\"yes\">α</italic> Centauri B, IUE <italic toggle=\"yes\">α</italic> Centauri B, IUE <italic toggle=\"yes\">ϵ</italic> Eri, IUE <italic toggle=\"yes\">ξ</italic> Boo). Various periodic structures within the FUV flux were detected, with most significant being a 79 days frequency present within the IUE observations of <italic toggle=\"yes\">ξ</italic> Boo, with a significance of 6<italic toggle=\"yes\">σ</italic>, and a periodic signal in the FUV observations of <italic toggle=\"yes\">α</italic> Centauri B, for both HST and IUE measurements, at ≈210 days frequency with significance of 3<italic toggle=\"yes\">σ</italic> and 3.7<italic toggle=\"yes\">σ</italic>, respectively. Our results suggest that extreme ultraviolet flux from cool stars varies by less than a factor of two on decade timescales, significantly sm","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"46 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009714","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 : 2024-02-06DOI: 10.1088/1538-3873/ad1f3d
Blake J. Bottesi, Marco Fatuzzo, Lisa Holden, Kendra Herweck
Ambipolar diffusion is the mechanism believed to be responsible for the loss of magnetic support in dense molecular cloud cores, and is therefore likely to play a key role in the star formation process. As such, this mechanism has been studied extensively both semianalytically and numerically. We build upon this existing body of work by considering a one-dimensional self-gravitating gas with a polytropic equation of state (P ∝ ρϵ), and consider cases that range from softer (ϵ < 1) to stiffer (ϵ > 1) than isothermal. Our results indicate that the diffusion time is not very sensitive to the polytropic exponent ϵ when stiffer than isothermal, but is sensitive to the exponent when softer than isothermal. Additionally, the presence of magnetic and density fluctuations causes the ambipolar diffusion process to speed up, with the shortest diffusion times obtained for gases with large initial magnetic to gas pressure ratios and fairly soft equations of state. However, the diffusion time starts to increase significantly for ϵ ≲ 0.5, indicating that such soft equations of state are inconsistent with observations.
{"title":"Ambipolar Diffusion with a Polytropic Equation of State","authors":"Blake J. Bottesi, Marco Fatuzzo, Lisa Holden, Kendra Herweck","doi":"10.1088/1538-3873/ad1f3d","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1f3d","url":null,"abstract":"Ambipolar diffusion is the mechanism believed to be responsible for the loss of magnetic support in dense molecular cloud cores, and is therefore likely to play a key role in the star formation process. As such, this mechanism has been studied extensively both semianalytically and numerically. We build upon this existing body of work by considering a one-dimensional self-gravitating gas with a polytropic equation of state (<italic toggle=\"yes\">P</italic> ∝ <italic toggle=\"yes\">ρ</italic>\u0000<sup>\u0000<italic toggle=\"yes\">ϵ</italic>\u0000</sup>), and consider cases that range from softer (<italic toggle=\"yes\">ϵ</italic> < 1) to stiffer (<italic toggle=\"yes\">ϵ</italic> > 1) than isothermal. Our results indicate that the diffusion time is not very sensitive to the polytropic exponent <italic toggle=\"yes\">ϵ</italic> when stiffer than isothermal, but is sensitive to the exponent when softer than isothermal. Additionally, the presence of magnetic and density fluctuations causes the ambipolar diffusion process to speed up, with the shortest diffusion times obtained for gases with large initial magnetic to gas pressure ratios and fairly soft equations of state. However, the diffusion time starts to increase significantly for <italic toggle=\"yes\">ϵ</italic> ≲ 0.5, indicating that such soft equations of state are inconsistent with observations.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"169 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764453","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 : 2024-02-05DOI: 10.1088/1538-3873/ad1ed3
Atila Poro, Mehmet Tanriver, Raul Michel, Ehsan Paki
Multiband photometric investigations for eight binary systems of the W Ursae Majoris-type are presented. Six systems are presented for the first time to analyze their light curves. All the analyzed systems have a temperature below 5000 K and an orbital period of less than 0.28 days. We extracted primary and secondary minima from the ground-based observations of these systems. According to a few observations reported in the literature, linear fits were considered in the O − C diagrams, and new ephemerides were presented. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs code. The results of the mass ratio and fillout factor indicate that the systems are contact binary stars. Six of them showed the O’Connell effect, and a cold starspot on each companion was required for light curve solutions. Their absolute parameters were estimated and evaluated by two other methods. In this study, the empirical relationship between the orbital period and semimajor axis was updated using a sample consisting of 414 contact binary systems and the Monte Carlo Markov Chain approach. Also, using Machine Learning and the Artificial Neural Network model, the relationship between P–T1–M1 was updated for a better estimation of the mass of the primary star.
本文介绍了对八个大熊座W型双星系统的多波段测光研究。其中六个系统的光变曲线分析是首次提出。所有分析的系统温度都低于 5000 K，轨道周期小于 0.28 天。我们从这些系统的地面观测数据中提取了主极小值和次极小值。根据文献中报道的一些观测数据，我们考虑对 O - C 图进行线性拟合，并提出了新的星历表。光变曲线的求解使用了 "PHysics Of Eclipsing BinariEs "代码。质量比和填充因子的结果表明，这些系统是接触双星。其中六颗出现了奥康纳尔效应，每个伴星上都需要一个冷星斑来进行光曲线求解。它们的绝对参数是用另外两种方法估算和评价的。在这项研究中，利用由 414 个接触双星系统组成的样本和蒙特卡罗马尔可夫链方法更新了轨道周期和半长轴之间的经验关系。此外，还利用机器学习和人工神经网络模型更新了 P-T1-M1 之间的关系，以便更好地估计主星的质量。
{"title":"Global Parameters of Eight W UMa-type Binary Systems","authors":"Atila Poro, Mehmet Tanriver, Raul Michel, Ehsan Paki","doi":"10.1088/1538-3873/ad1ed3","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1ed3","url":null,"abstract":"Multiband photometric investigations for eight binary systems of the W Ursae Majoris-type are presented. Six systems are presented for the first time to analyze their light curves. All the analyzed systems have a temperature below 5000 K and an orbital period of less than 0.28 days. We extracted primary and secondary minima from the ground-based observations of these systems. According to a few observations reported in the literature, linear fits were considered in the <italic toggle=\"yes\">O</italic> − <italic toggle=\"yes\">C</italic> diagrams, and new ephemerides were presented. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs code. The results of the mass ratio and fillout factor indicate that the systems are contact binary stars. Six of them showed the O’Connell effect, and a cold starspot on each companion was required for light curve solutions. Their absolute parameters were estimated and evaluated by two other methods. In this study, the empirical relationship between the orbital period and semimajor axis was updated using a sample consisting of 414 contact binary systems and the Monte Carlo Markov Chain approach. Also, using Machine Learning and the Artificial Neural Network model, the relationship between <italic toggle=\"yes\">P</italic>–<italic toggle=\"yes\">T</italic>\u0000<sub>1</sub>–<italic toggle=\"yes\">M</italic>\u0000<sub>1</sub> was updated for a better estimation of the mass of the primary star.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764361","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 : 2024-02-05DOI: 10.1088/1538-3873/ad1c98
Paul Goudfrooij, David Grumm, Kevin Volk, Howard Bushouse
We present an algorithm that mitigates the effects of charge migration due to the “brighter-fatter effect” (BFE) that occurs for highly illuminated stars in the Teledyne HAWAII-2RG detectors used in the NIRCam, NIRISS, and NIRSpec science instruments aboard the James Webb Space Telescope (JWST). The impact of this effect is most significant for photometry and spectrophotometry of bright stars in data for which the point-spread function (PSF) is undersampled, which is the case for several observing modes of the NIRISS instrument. The main impact of BFE to NIRISS data is incorrect count rate determinations for pixels in the central regions of PSFs of bright stars due to jump detections that are caused by charge migration from peak pixels to surrounding pixels. The effect is especially significant for bright compact sources in resampled, distortion-free images produced by the drizzle algorithm: quantitatively, apparent flux losses of >50% can occur in such images due to BFE. We describe the algorithm of the “charge_migration” mitigation step that has been implemented in version 10.0 of the operational JWST calibration pipeline as of 2023 December 5. We illustrate the impact of this step in terms of the resulting improvements of the precision of imaging photometry of point sources. The algorithm renders the effects of BFE on photometry and surface brightness measurements to stay within 1%.
{"title":"An Algorithm to Mitigate Charge Migration Effects in Data from the Near Infrared Imager and Slitless Spectrograph on the James Webb Space Telescope* * This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs #1083, 1093, 1094, and 1096.","authors":"Paul Goudfrooij, David Grumm, Kevin Volk, Howard Bushouse","doi":"10.1088/1538-3873/ad1c98","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1c98","url":null,"abstract":"We present an algorithm that mitigates the effects of charge migration due to the “brighter-fatter effect” (BFE) that occurs for highly illuminated stars in the Teledyne HAWAII-2RG detectors used in the NIRCam, NIRISS, and NIRSpec science instruments aboard the James Webb Space Telescope (JWST). The impact of this effect is most significant for photometry and spectrophotometry of bright stars in data for which the point-spread function (PSF) is undersampled, which is the case for several observing modes of the NIRISS instrument. The main impact of BFE to NIRISS data is incorrect count rate determinations for pixels in the central regions of PSFs of bright stars due to jump detections that are caused by charge migration from peak pixels to surrounding pixels. The effect is especially significant for bright compact sources in resampled, distortion-free images produced by the drizzle algorithm: quantitatively, apparent flux losses of >50% can occur in such images due to BFE. We describe the algorithm of the “<monospace>charge</monospace>_<monospace>migration</monospace>” mitigation step that has been implemented in version 10.0 of the operational JWST calibration pipeline as of 2023 December 5. We illustrate the impact of this step in terms of the resulting improvements of the precision of imaging photometry of point sources. The algorithm renders the effects of BFE on photometry and surface brightness measurements to stay within 1%.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"25 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764360","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}
We present a data reduction pipeline written in Python for data obtained with the near-infrared cross-dispersed echelle spectrograph, WINERED, which yields a 0.91–1.35 μm spectrum with the resolving power of Rmax≡λ/Δλ=28,000 or 70,000 depending on the observing mode. The pipeline was developed to efficiently extract the spectrum from the raw data with high quality. It comprises two modes: the calibration and the science mode. The calibration mode automatically produces the flat-fielding image, bad pixel map, echellogram distortion map and the dispersion solution from the set of the calibration data. Using calibration images and parameters, the science data of astronomical objects can be reduced automatically using the science mode. The science mode is also used for the real-time quick look at the data during observations. An example of the spectra reduced with WARP is presented. The effect of the highly inclined slit image on the spectral resolution is discussed.
{"title":"WARP: The Data Reduction Pipeline for the WINERED Spectrograph","authors":"Satoshi Hamano, Yuji Ikeda, Shogo Otsubo, Haruki Katoh, Kei Fukue, Noriyuki Matsunaga, Daisuke Taniguchi, Hideyo Kawakita, Keiichi Takenaka, Sohei Kondo, Hiroaki Sameshima","doi":"10.1088/1538-3873/ad1b38","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1b38","url":null,"abstract":"We present a data reduction pipeline written in Python for data obtained with the near-infrared cross-dispersed echelle spectrograph, WINERED, which yields a 0.91–1.35 <italic toggle=\"yes\">μ</italic>m spectrum with the resolving power of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${R}_{max }equiv lambda /{rm{Delta }}lambda ={rm{28,000}}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mrow><mml:mi>R</mml:mi></mml:mrow><mml:mrow><mml:mi>max</mml:mi></mml:mrow></mml:msub><mml:mo>≡</mml:mo><mml:mi>λ</mml:mi><mml:mrow><mml:mo stretchy=\"true\">/</mml:mo></mml:mrow><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:mi>λ</mml:mi><mml:mo>=</mml:mo><mml:mi mathvariant=\"normal\">28,000</mml:mi></mml:math>\u0000<inline-graphic xlink:href=\"paspad1b38ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> or 70,000 depending on the observing mode. The pipeline was developed to efficiently extract the spectrum from the raw data with high quality. It comprises two modes: the calibration and the science mode. The calibration mode automatically produces the flat-fielding image, bad pixel map, echellogram distortion map and the dispersion solution from the set of the calibration data. Using calibration images and parameters, the science data of astronomical objects can be reduced automatically using the science mode. The science mode is also used for the real-time quick look at the data during observations. An example of the spectra reduced with WARP is presented. The effect of the highly inclined slit image on the spectral resolution is discussed.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"77 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764562","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 : 2024-02-01DOI: 10.1088/1538-3873/ad1f3e
Zhiyuan Ma, Haojing Yan, Bangzheng Sun, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Rogier A. Windhorst, Jordan C. J. D’Silva, Anton M. Koekemoer, Dan Coe, Christopher J. Conselice, Simon P. Driver, Brenda Frye, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Rafael Ortiz, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Christopher N. A. Willmer, Heidi B. Hammel, Stefanie N. Milam, Nathan J. Adams, Cheng Cheng, Nimish P. Hathi
The Prime Extragalactic Areas for Reionization and Lensing Science, a James Webb Space Telescope (JWST) GTO program, obtained a set of unique NIRCam observations that have enabled us to significantly improve the default photometric calibration across both NIRCam modules. The observations consisted of three epochs of 4-band (F150W, F200W, F356W, and F444W) NIRCam imaging in the Spitzer IRAC Dark Field (IDF). The three epochs were six months apart and spanned the full duration of Cycle 1. As the IDF is in the JWST continuous viewing zone, we were able to design the observations such that the two modules of NIRCam, modules A and B, were flipped by 180° and completely overlapped each other’s footprints in alternate epochs. We were therefore able to directly compare the photometry of the same objects observed with different modules and detectors, and we found significant photometric residuals up to ∼0.05 mag in some detectors and filters, for the default version of the calibration files that we used (jwst_1039.pmap). Moreover, there are multiplicative gradients present in the data obtained in the two long-wavelength bands. The problem is less severe in the data reduced using the latest pmap (jwst_1130.pmap as of 2023 September), but it is still present, and is non-negligible. We provide a recipe to correct for this systematic effect to bring the two modules onto a more consistent calibration, to a photometric precision better than ∼0.02 mag.
詹姆斯-韦伯太空望远镜（JWST）GTO计划中的 "用于再电离和透镜科学的主要河外星系区域"（Prime Extragalactic Areas for Reionization and Lensing Science）获得了一组独特的NIRCam观测数据，使我们能够显著改进两个NIRCam模块的默认测光校准。这些观测包括在斯皮策 IRAC 暗场（IDF）中对 4 波段（F150W、F200W、F356W 和 F444W）NIRCam 成像的三个纪元。这三个时间相隔六个月，跨越了整个周期 1。由于 IDF 位于 JWST 的连续观测区内，我们在设计观测时将 NIRCam 的两个模块（模块 A 和模块 B）翻转 180°，在交替的时间段内彼此的足迹完全重叠。因此，我们可以直接比较使用不同模块和探测器观测到的同一天体的光度，我们发现，在我们使用的默认版本的校准文件（jwst_1039.pmap）中，某些探测器和滤光片的光度残差高达 ∼0.05 mag。此外，在两个长波段获得的数据中还存在乘法梯度。在使用最新 pmap（截至 9 月 2023 日的 jwst_1130.pmap）缩减的数据中，这个问题没有那么严重，但仍然存在，而且不可忽略。我们提供了一个校正这一系统性影响的方法，使两个模块的校准更加一致，光度精度优于 ∼ 0.02 马格。
{"title":"JWST’s PEARLS: Improved Flux Calibration for NIRCam","authors":"Zhiyuan Ma, Haojing Yan, Bangzheng Sun, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Rogier A. Windhorst, Jordan C. J. D’Silva, Anton M. Koekemoer, Dan Coe, Christopher J. Conselice, Simon P. Driver, Brenda Frye, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Rafael Ortiz, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Christopher N. A. Willmer, Heidi B. Hammel, Stefanie N. Milam, Nathan J. Adams, Cheng Cheng, Nimish P. Hathi","doi":"10.1088/1538-3873/ad1f3e","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1f3e","url":null,"abstract":"The Prime Extragalactic Areas for Reionization and Lensing Science, a James Webb Space Telescope (JWST) GTO program, obtained a set of unique NIRCam observations that have enabled us to significantly improve the default photometric calibration across both NIRCam modules. The observations consisted of three epochs of 4-band (F150W, F200W, F356W, and F444W) NIRCam imaging in the Spitzer IRAC Dark Field (IDF). The three epochs were six months apart and spanned the full duration of Cycle 1. As the IDF is in the JWST continuous viewing zone, we were able to design the observations such that the two modules of NIRCam, modules A and B, were flipped by 180° and completely overlapped each other’s footprints in alternate epochs. We were therefore able to directly compare the photometry of the same objects observed with different modules and detectors, and we found significant photometric residuals up to ∼0.05 mag in some detectors and filters, for the default version of the calibration files that we used (<monospace>jwst</monospace>_<monospace>1039.pmap</monospace>). Moreover, there are multiplicative gradients present in the data obtained in the two long-wavelength bands. The problem is less severe in the data reduced using the latest pmap (<monospace>jwst</monospace>_<monospace>1130.pmap</monospace> as of 2023 September), but it is still present, and is non-negligible. We provide a recipe to correct for this systematic effect to bring the two modules onto a more consistent calibration, to a photometric precision better than ∼0.02 mag.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"17 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764545","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 : 2024-01-30DOI: 10.1088/1538-3873/ad1ba7
Pranav Nagarajan, Kareem El-Badry, Amaury H. M. J. Triaud, Thomas A. Baycroft, David Latham, Allyson Bieryla, Lars A. Buchhave, Hans-Walter Rix, Eliot Quataert, Andrew Howard, Howard Isaacson, Melissa J. Hobson
We present high-precision radial velocity observations of Gaia BH1, the nearest known black hole (BH). The system contains a solar-type G star orbiting a massive dark companion, which could be either a single BH or an inner BH + BH binary. A BH + BH binary is expected in some models where Gaia BH1 formed as a hierarchical triple, which is attractive because they avoid many of the difficulties associated with forming the system through isolated binary evolution. Our observations test the inner binary scenario. We have measured 115 precise RVs of the G star, including 40 from ESPRESSO with a precision of 3–5 m s−1, and 75 from other instruments with a typical precision of 30–100 m s−1. Our observations span 2.33 orbits of the G star and are concentrated near a periastron passage, when perturbations due to an inner binary would be largest. The RVs are well-fit by a Keplerian two-body orbit and show no convincing evidence of an inner binary. Using REBOUND simulations of hierarchical triples with a range of inner periods, mass ratios, eccentricities, and orientations, we show that plausible inner binaries with periods Pinner ≳ 1.5 days would have produced larger deviations from a Keplerian orbit than observed. Binaries with Pinner ≲ 1.5 days are consistent with the data, but these would merge within a Hubble time and would thus imply fine-tuning. We present updated parameters of Gaia BH1's orbit. The RVs yield a spectroscopic mass function fMBH=3.9358±0.0002M⊙—about 7000σ above the ∼2.5 M⊙ maximum neutron star mass. Including the inclination constraint from Gaia astrometry, this implies a BH mass of MBH = 9.27 ± 0.10 M⊙.
我们展示了对已知最近的黑洞 Gaia BH1 的高精度径向速度观测结果。该系统包含一颗太阳型G星，围绕着一颗大质量暗伴星运行，这颗伴星可能是单个黑洞，也可能是内部的黑洞+黑洞双星。在一些模型中，盖亚BH1会形成一个分层三重BH+BH双星，这很有吸引力，因为它们避免了通过孤立双星演化形成系统所带来的许多困难。我们的观测检验了内部双星的情况。我们测量了 G 星的 115 个精确 RV 值，其中 40 个来自 ESPRESSO，精度为 3-5 m s-1，75 个来自其他仪器，精度通常为 30-100 m s-1。我们的观测数据跨越了 G 星的 2.33 个轨道，并集中在近地轨道附近，此时内部双星造成的扰动最大。RV值与开普勒双体轨道拟合良好，没有显示出内部双星的令人信服的证据。我们利用REBOUND模拟了具有一系列内部周期、质量比、偏心率和方向的分级三体，结果表明周期Pinner ≳ 1.5天的可信内部双星会产生比观测到的更大的开普勒轨道偏差。Pinner≲1.5天的双星与数据一致，但这些双星会在哈勃时间内合并，因此意味着微调。我们给出了 Gaia BH1 轨道的最新参数。RVs得出的光谱质量函数fMBH=3.9358±0.0002M⊙-比∼2.5M⊙最大中子星质量高出约7000σ。包括来自盖亚天体测量的倾角约束，这意味着BH质量为MBH=9.27±0.10 M⊙。
{"title":"ESPRESSO Observations of Gaia BH1: High-precision Orbital Constraints and no Evidence for an Inner Binary","authors":"Pranav Nagarajan, Kareem El-Badry, Amaury H. M. J. Triaud, Thomas A. Baycroft, David Latham, Allyson Bieryla, Lars A. Buchhave, Hans-Walter Rix, Eliot Quataert, Andrew Howard, Howard Isaacson, Melissa J. Hobson","doi":"10.1088/1538-3873/ad1ba7","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1ba7","url":null,"abstract":"We present high-precision radial velocity observations of Gaia BH1, the nearest known black hole (BH). The system contains a solar-type G star orbiting a massive dark companion, which could be either a single BH or an inner BH + BH binary. A BH + BH binary is expected in some models where Gaia BH1 formed as a hierarchical triple, which is attractive because they avoid many of the difficulties associated with forming the system through isolated binary evolution. Our observations test the inner binary scenario. We have measured 115 precise RVs of the G star, including 40 from ESPRESSO with a precision of 3–5 m s<sup>−1</sup>, and 75 from other instruments with a typical precision of 30–100 m s<sup>−1</sup>. Our observations span 2.33 orbits of the G star and are concentrated near a periastron passage, when perturbations due to an inner binary would be largest. The RVs are well-fit by a Keplerian two-body orbit and show no convincing evidence of an inner binary. Using <monospace>REBOUND</monospace> simulations of hierarchical triples with a range of inner periods, mass ratios, eccentricities, and orientations, we show that plausible inner binaries with periods <italic toggle=\"yes\">P</italic>\u0000<sub>inner</sub> ≳ 1.5 days would have produced larger deviations from a Keplerian orbit than observed. Binaries with <italic toggle=\"yes\">P</italic>\u0000<sub>inner</sub> ≲ 1.5 days are consistent with the data, but these would merge within a Hubble time and would thus imply fine-tuning. We present updated parameters of Gaia BH1's orbit. The RVs yield a spectroscopic mass function <inline-formula>\u0000<tex-math>\u0000<?CDATA $fleft({M}_{mathrm{BH}}right)=3.9358pm 0.0002,{M}_{odot }$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi>f</mml:mi><mml:mfenced close=\")\" open=\"(\"><mml:mrow><mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:mi>BH</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:mfenced><mml:mo>=</mml:mo><mml:mn>3.9358</mml:mn><mml:mo>±</mml:mo><mml:mn>0.0002</mml:mn><mml:mspace width=\"0.25em\"></mml:mspace><mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:mo>⊙</mml:mo></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"paspad1ba7ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>—about 7000<italic toggle=\"yes\">σ</italic> above the ∼2.5 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub> maximum neutron star mass. Including the inclination constraint from Gaia astrometry, this implies a BH mass of <italic toggle=\"yes\">M</italic>\u0000<sub>BH</sub> = 9.27 ± 0.10 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub>.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764358","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 : 2024-01-30DOI: 10.1088/1538-3873/ad1b36
Bernard J. Rauscher
NSClean is an algorithm and python package for removing faint vertical banding and “picture frame noise” from JWST Near Infrared Spectrograph (NIRSpec) images. NSClean uses known dark areas to fit a background model to each exposure in Fourier space. When the model is subtracted, it removes nearly all correlated noise. Compared to simpler strategies like subtracting the rolling median, NSClean is more thorough and uniform. NSClean has been developed and tested for NIRSpec IFU mode data, although it can be used on other NIRSpec modes as well. NSClean is computationally undemanding, requiring only a few seconds to clean an image on a typical laptop. The NSClean package is freely available from the NASA JWST website.
{"title":"NSClean: An Algorithm for Removing Correlated Noise from JWST NIRSpec Images","authors":"Bernard J. Rauscher","doi":"10.1088/1538-3873/ad1b36","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1b36","url":null,"abstract":"NSClean is an algorithm and python package for removing faint vertical banding and “picture frame noise” from JWST Near Infrared Spectrograph (NIRSpec) images. NSClean uses known dark areas to fit a background model to each exposure in Fourier space. When the model is subtracted, it removes nearly all correlated noise. Compared to simpler strategies like subtracting the rolling median, NSClean is more thorough and uniform. NSClean has been developed and tested for NIRSpec IFU mode data, although it can be used on other NIRSpec modes as well. NSClean is computationally undemanding, requiring only a few seconds to clean an image on a typical laptop. The NSClean package is freely available from the NASA JWST website.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"24 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764559","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 : 2024-01-22DOI: 10.1088/1538-3873/ad1412
Jason D. Eastman
We present a novel eccentricity parameterization for transit-only fits that allows us to efficiently sample the eccentricity and argument of periastron, while being able to generate a self-consistent model of a planet in a Keplerian orbit around its host star. With simulated fits of 330 randomly generated systems, we demonstrate that typical parameterizations often lead to inaccurate and overly precise determinations of the planetary eccentricity. However, our proposed parameterization allows us to accurately—and often precisely—recover the eccentricity for the simulated planetary systems with only transit data available.
{"title":"A Novel Eccentricity Parameterization for Transit-only Models","authors":"Jason D. Eastman","doi":"10.1088/1538-3873/ad1412","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1412","url":null,"abstract":"We present a novel eccentricity parameterization for transit-only fits that allows us to efficiently sample the eccentricity and argument of periastron, while being able to generate a self-consistent model of a planet in a Keplerian orbit around its host star. With simulated fits of 330 randomly generated systems, we demonstrate that typical parameterizations often lead to inaccurate and overly precise determinations of the planetary eccentricity. However, our proposed parameterization allows us to accurately—and often precisely—recover the eccentricity for the simulated planetary systems with only transit data available.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"11 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764447","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 : 2024-01-12DOI: 10.1088/1538-3873/ad0ca3
Mario L. Vicuña, Jorge F. Silva, Rene A. Mendez, Marcos E. Orchard, Sebastian Espinosa, Jeremy Tregloan-Reed
In this paper we study the joint determination of source and background flux for point sources as observed by digital array detectors. We explicitly compute the two-dimensional Cramér–Rao absolute lower bound (CRLB) as well as the performance bounds for high-dimensional implicit estimators from a generalized Taylor expansion. This later approach allows us to obtain computable prescriptions for the bias and variance of the joint estimators. We compare these prescriptions with empirical results from numerical simulations in the case of the weighted least squares estimator (introducing an improved version, denoted stochastic weighted least-squares) as well as with the maximum likelihood estimator, finding excellent agreement. We demonstrate that these estimators provide quasi-unbiased joint estimations of the flux and background, with a variance that approaches the CRLB very tightly and are, hence, optimal, unlike the case of sequential estimation used commonly in astronomical photometry which is sub-optimal. We compare our predictions with numerical simulations of realistic observations, as well as with observations of a bona fide non-variable stellar source observed with TESS, and compare it to the results from the sequential estimation of background and flux, confirming our theoretical expectations. Our practical estimators can be used as benchmarks for general photometric pipelines, or for applications that require maximum precision and accuracy in absolute photometry.
{"title":"Optimal Photometry of Point Sources: Joint Source Flux and Background Determination on Array Detectors—from Theory to Practical Implementation","authors":"Mario L. Vicuña, Jorge F. Silva, Rene A. Mendez, Marcos E. Orchard, Sebastian Espinosa, Jeremy Tregloan-Reed","doi":"10.1088/1538-3873/ad0ca3","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0ca3","url":null,"abstract":"In this paper we study the joint determination of source and background flux for point sources as observed by digital array detectors. We explicitly compute the two-dimensional Cramér–Rao absolute lower bound (CRLB) as well as the performance bounds for high-dimensional implicit estimators from a generalized Taylor expansion. This later approach allows us to obtain computable prescriptions for the bias and variance of the joint estimators. We compare these prescriptions with empirical results from numerical simulations in the case of the weighted least squares estimator (introducing an improved version, denoted stochastic weighted least-squares) as well as with the maximum likelihood estimator, finding excellent agreement. We demonstrate that these estimators provide quasi-unbiased joint estimations of the flux and background, with a variance that approaches the CRLB very tightly and are, hence, optimal, unlike the case of sequential estimation used commonly in astronomical photometry which is sub-optimal. We compare our predictions with numerical simulations of realistic observations, as well as with observations of a bona fide non-variable stellar source observed with TESS, and compare it to the results from the sequential estimation of background and flux, confirming our theoretical expectations. Our practical estimators can be used as benchmarks for general photometric pipelines, or for applications that require maximum precision and accuracy in absolute photometry.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"4 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139507094","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}
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