Pub Date : 2024-08-20DOI: 10.1088/1538-3873/ad692d
Yeon-Ho Choi, Myeong-Gu Park, Kang-Min Kim, Jae-Rim Koo, Tae-Yang Bang, Chan Park, Jeong-Gyun Jang, Inwoo Han, Bi-Ho Jang, Jong Ung Lee, Ueejeong Jeong, Byeong-Cheol Lee
The SPECtrophotometer for TRansmission spectroscopy of exoplanets (SPECTR) is a new low-resolution optical (3800–6850 Å) spectrophotometer installed at the Bohyunsan Optical Astronomy Observatory 1.8 m telescope. SPECTR is designed for observing the transmission spectra of transiting exoplanets. Unique features of SPECTR are its long slit length of 10′ which facilitates observing the target and the comparison star simultaneously, and its wide slit width to minimize slit losses. SPECTR will be used to survey exoplanets, such as those identified by the Transiting Exoplanet Survey Satellite, providing information about their radii across the wavelength range. In this paper, we present the design of SPECTR and the observational results of the partial transit of HD 189733 b and a full transit of Qatar-8 b. Analyses show the SPECTR’s capability on the white light curves with an accuracy of one ppt. The transmission spectrum of HD 189733 b shows general agreement with previous studies.
用于系外行星透射光谱分析的分光光度计（SPECTR）是安装在宝云山光学天文观测台 1.8 米望远镜上的新型低分辨率光学分光光度计（3800-6850 Å）。SPECTR 专为观测凌日系外行星的透射光谱而设计。SPECTR 的独特之处在于其长达 10′的狭缝长度便于同时观测目标和对比恒星，其宽大的狭缝宽度可最大限度地减少狭缝损耗。SPECTR 将用于巡天系外行星，例如那些由凌日系外行星巡天卫星发现的系外行星，提供其在整个波长范围内的半径信息。本文介绍了 SPECTR 的设计以及 HD 189733 b 部分凌日和 Qatar-8 b 全部凌日的观测结果。HD 189733 b 的透射光谱与以前的研究结果基本一致。
{"title":"SPECtrophotometer for TRansmission Spectroscopy of Exoplanets (SPECTR)","authors":"Yeon-Ho Choi, Myeong-Gu Park, Kang-Min Kim, Jae-Rim Koo, Tae-Yang Bang, Chan Park, Jeong-Gyun Jang, Inwoo Han, Bi-Ho Jang, Jong Ung Lee, Ueejeong Jeong, Byeong-Cheol Lee","doi":"10.1088/1538-3873/ad692d","DOIUrl":"https://doi.org/10.1088/1538-3873/ad692d","url":null,"abstract":"The SPECtrophotometer for TRansmission spectroscopy of exoplanets (SPECTR) is a new low-resolution optical (3800–6850 Å) spectrophotometer installed at the Bohyunsan Optical Astronomy Observatory 1.8 m telescope. SPECTR is designed for observing the transmission spectra of transiting exoplanets. Unique features of SPECTR are its long slit length of 10′ which facilitates observing the target and the comparison star simultaneously, and its wide slit width to minimize slit losses. SPECTR will be used to survey exoplanets, such as those identified by the Transiting Exoplanet Survey Satellite, providing information about their radii across the wavelength range. In this paper, we present the design of SPECTR and the observational results of the partial transit of HD 189733 b and a full transit of Qatar-8 b. Analyses show the SPECTR’s capability on the white light curves with an accuracy of one ppt. The transmission spectrum of HD 189733 b shows general agreement with previous studies.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183190","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 : 2024-08-20DOI: 10.1088/1538-3873/ad68a4
Aswin Suresh, Viraj Karambelkar, Mansi M. Kasliwal, Michael C. B. Ashley, Kishalay De, Matthew J. Hankins, Anna M. Moore, Jamie Soon, Roberto Soria, Tony Travouillon, Kayton K. Truong
Long Period Variables (LPVs) are stars with periods of several hundred days, representing the late, dust-enshrouded phase of stellar evolution in low to intermediate mass stars. In this paper, we present a catalog of 154,755 LPVs using near-IR lightcurves from the Palomar Gattini-IR (PGIR) survey. PGIR has been surveying the entire accessible northern sky (δ > −28°) in the J-band at a cadence of 2–3 days since 2018 September, and has produced J-band lightcurves for more than 60 million sources. We used a gradient-boosted decision tree classifier trained on a comprehensive feature set extracted from PGIR lightcurves to search for LPVs in this data set. We developed a parallelized and optimized code to extract features at a rate of ∼0.1 s per lightcurve. Our model can successfully distinguish LPVs from other stars with a true positive rate of 95%. Cross-matching with known LPVs, we find 70,369 (∼46%) new LPVs in our catalog.
{"title":"An Automated Catalog of Long Period Variables using Infrared Lightcurves from Palomar Gattini-IR","authors":"Aswin Suresh, Viraj Karambelkar, Mansi M. Kasliwal, Michael C. B. Ashley, Kishalay De, Matthew J. Hankins, Anna M. Moore, Jamie Soon, Roberto Soria, Tony Travouillon, Kayton K. Truong","doi":"10.1088/1538-3873/ad68a4","DOIUrl":"https://doi.org/10.1088/1538-3873/ad68a4","url":null,"abstract":"Long Period Variables (LPVs) are stars with periods of several hundred days, representing the late, dust-enshrouded phase of stellar evolution in low to intermediate mass stars. In this paper, we present a catalog of 154,755 LPVs using near-IR lightcurves from the Palomar Gattini-IR (PGIR) survey. PGIR has been surveying the entire accessible northern sky (<italic toggle=\"yes\">δ</italic> > −28°) in the <italic toggle=\"yes\">J</italic>-band at a cadence of 2–3 days since 2018 September, and has produced <italic toggle=\"yes\">J</italic>-band lightcurves for more than 60 million sources. We used a gradient-boosted decision tree classifier trained on a comprehensive feature set extracted from PGIR lightcurves to search for LPVs in this data set. We developed a parallelized and optimized code to extract features at a rate of ∼0.1 s per lightcurve. Our model can successfully distinguish LPVs from other stars with a true positive rate of 95%. Cross-matching with known LPVs, we find 70,369 (∼46%) new LPVs in our catalog.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183189","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}
The groundbreaking detection of gravitational waves (GWs) has ushered in a new era of astronomical observation, granting us access to cosmic phenomena that are imperceptible to electromagnetic waves. The inherently weak GW signals coupled with the substantial uncertainties in source localization pose significant challenges to the field of astronomy. In this paper, we introduce innovative strategies to enhance the efficiency of observing electromagnetic counterparts to GW events, thereby unlocking further secrets of the cosmos. We present a novel technique for designing observation targets and establishing priorities, progressing from the epicenter to the periphery within the boundaries of the GW error sky region. This method has significantly reduced the average slewing distance of telescopes by 41% compared to traditional methods, thus enhancing observational efficiency. Additionally, we have developed a collaborative observation strategy for telescope networks, allocating observation targets based on the field-of-view (FOV) sizes of individual telescopes. This ensures comprehensive coverage without redundancy, allowing a network of four telescopes to cover a sky area and accumulate observation probability more than four times that of a single telescope operating independently over an equivalent period. Building upon these strategies, we have significantly upgraded GWOPS, the GW Follow-up Observation Planning System developed by the China-VO team, to provide precise observational planning for large FOV (greater than 1 square degree) telescope networks. The system also features a web-based user interface that presents the GW error sky area and observation planning results in a graphical format, significantly improving user interaction and experience. The research presented herein equips astronomers with a robust toolkit, advancing the efficiency of searching for and studying electromagnetic counterparts to GW events, and heralding new frontiers in the research of astrophysics and cosmology.
{"title":"Enhancing GWOPS Capabilities for Coordinated Multi-Telescope Detection of Gravitational Wave Electromagnetic Counterparts","authors":"Penghui Ma, Yunfei Xu, Jingwei Hu, Zhen Zhang, Liang Ge, Min He, Shanshan Li, Linying Mi, Changhua Li, Dongwei Fan, Chenzhou Cui","doi":"10.1088/1538-3873/ad6710","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6710","url":null,"abstract":"The groundbreaking detection of gravitational waves (GWs) has ushered in a new era of astronomical observation, granting us access to cosmic phenomena that are imperceptible to electromagnetic waves. The inherently weak GW signals coupled with the substantial uncertainties in source localization pose significant challenges to the field of astronomy. In this paper, we introduce innovative strategies to enhance the efficiency of observing electromagnetic counterparts to GW events, thereby unlocking further secrets of the cosmos. We present a novel technique for designing observation targets and establishing priorities, progressing from the epicenter to the periphery within the boundaries of the GW error sky region. This method has significantly reduced the average slewing distance of telescopes by 41% compared to traditional methods, thus enhancing observational efficiency. Additionally, we have developed a collaborative observation strategy for telescope networks, allocating observation targets based on the field-of-view (FOV) sizes of individual telescopes. This ensures comprehensive coverage without redundancy, allowing a network of four telescopes to cover a sky area and accumulate observation probability more than four times that of a single telescope operating independently over an equivalent period. Building upon these strategies, we have significantly upgraded GWOPS, the GW Follow-up Observation Planning System developed by the China-VO team, to provide precise observational planning for large FOV (greater than 1 square degree) telescope networks. The system also features a web-based user interface that presents the GW error sky area and observation planning results in a graphical format, significantly improving user interaction and experience. The research presented herein equips astronomers with a robust toolkit, advancing the efficiency of searching for and studying electromagnetic counterparts to GW events, and heralding new frontiers in the research of astrophysics and cosmology.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183191","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}
Astrometry from Gaia DR3 has enabled the discovery of a sample of 3000+ binaries containing white dwarfs (WD) and main-sequence (MS) stars in relatively wide orbits, with orbital periods Porb = (100–1000) days. This population was not predicted by binary population synthesis models before Gaia and—if the Gaia orbits are robust—likely requires very efficient envelope ejection during common envelope evolution (CEE). To assess the reliability of the Gaia solutions, we measured multi-epoch radial velocities (RVs) of 31 WD+MS binary candidates with Porb = (40–300) days and AstroSpectroSB1 orbital solutions. We jointly fit the RVs and astrometry, allowing us to validate the Gaia solutions and tighten constraints on component masses. We find a high success rate for the Gaia solutions, with only 2 out of the 31 systems showing significant discrepancies between their Gaia orbital solutions and our RVs. Joint fitting of RVs and astrometry allows us to directly constrain the secondary-to-primary flux ratio S, and we find S≲0.02 for most objects, confirming the companions are indeed WDs. We tighten constraints on the binaries’ eccentricities, finding a median e ≈ 0.1. These eccentricities are much lower than those of normal MS+MS binaries at similar periods, but much higher than predicted for binaries formed via stable mass transfer. We present MESA single and binary evolution models to explore how the binaries may have formed. The orbits of most binaries in the sample can be produced through CEE that begins when the WD progenitor is an AGB star, corresponding to initial separations of 2–5 au. Roughly 50% of all post-common envelope binaries are predicted to have first interacted on the AGB, ending up in wide orbits like these systems.
{"title":"Wide Post-common Envelope Binaries from Gaia: Orbit Validation and Formation Models","authors":"Natsuko Yamaguchi, Kareem El-Badry, Natalie R. Rees, Sahar Shahaf, Tsevi Mazeh, Renŕ Andrae","doi":"10.1088/1538-3873/ad6809","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6809","url":null,"abstract":"Astrometry from Gaia DR3 has enabled the discovery of a sample of 3000+ binaries containing white dwarfs (WD) and main-sequence (MS) stars in relatively wide orbits, with orbital periods <italic toggle=\"yes\">P</italic>\u0000<sub>orb</sub> = (100–1000) days. This population was not predicted by binary population synthesis models before Gaia and—if the Gaia orbits are robust—likely requires very efficient envelope ejection during common envelope evolution (CEE). To assess the reliability of the Gaia solutions, we measured multi-epoch radial velocities (RVs) of 31 WD+MS binary candidates with <italic toggle=\"yes\">P</italic>\u0000<sub>orb</sub> = (40–300) days and <monospace>AstroSpectroSB1</monospace> orbital solutions. We jointly fit the RVs and astrometry, allowing us to validate the Gaia solutions and tighten constraints on component masses. We find a high success rate for the Gaia solutions, with only 2 out of the 31 systems showing significant discrepancies between their Gaia orbital solutions and our RVs. Joint fitting of RVs and astrometry allows us to directly constrain the secondary-to-primary flux ratio <inline-formula>\u0000<tex-math>\u0000<?CDATA ${ mathcal S }$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"script\">S</mml:mi></mml:math>\u0000<inline-graphic xlink:href=\"paspad6809ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, and we find <inline-formula>\u0000<tex-math>\u0000<?CDATA ${ mathcal S }lesssim 0.02$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"script\">S</mml:mi><mml:mo>≲</mml:mo><mml:mn>0.02</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"paspad6809ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> for most objects, confirming the companions are indeed WDs. We tighten constraints on the binaries’ eccentricities, finding a median <italic toggle=\"yes\">e</italic> ≈ 0.1. These eccentricities are much lower than those of normal MS+MS binaries at similar periods, but much higher than predicted for binaries formed via stable mass transfer. We present MESA single and binary evolution models to explore how the binaries may have formed. The orbits of most binaries in the sample can be produced through CEE that begins when the WD progenitor is an AGB star, corresponding to initial separations of 2–5 au. Roughly 50% of all post-common envelope binaries are predicted to have first interacted on the AGB, ending up in wide orbits like these systems.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183193","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 : 2024-08-08DOI: 10.1088/1538-3873/ad6692
Drake Deming, Guangwei Fu, Jeroen Bouwman, Daniel Dicken, Nestor Espinoza, Alistair Glasse, Thomas Greene, Sarah Kendrew, David Law, Jacob Lustig-Yaeger, Macarena Garcia Marin and Everett Schlawin
The Mid-Infrared Instrument Medium Resolution Spectrometer (the MRS) on JWST has potentially important advantages for transit and eclipse spectroscopy of exoplanets, including lack of saturation for bright host stars, wavelength span to longward of 20 µm, and JWST’s highest spectral resolving power. We here test the performance of the MRS for time series spectroscopy by observing the secondary eclipse of the bright stellar eclipsing binary R Canis Majoris. Our observations push the MRS into saturation at the shortest wavelength, more than for any currently known exoplanet system. We find strong charge migration between pixels that we mitigate using a custom data analysis pipeline. Our data analysis recovers much of the spatial charge migration by combining detector pixels at the group level, via weighting by the point-spread function. We achieve nearly photon-limited performance in time series data at wavelengths longward of 5.2 µm. In 2017, Snellen et al. suggested that the MRS could be used to detect carbon dioxide absorption from the atmosphere of the temperate planet orbiting Proxima Centauri. We infer that the relative spectral response of the MRS versus wavelength is sufficiently stable to make that detection feasible. As regards the secondary eclipse of this Algol-type binary, we measure the eclipse depth by summing our spectra over the wavelengths in four channels, and also measuring the eclipse depth as observed by TESS. Those eclipse depths require a temperature for the secondary star that is significantly hotter than previous observations in the optical to near-IR, probably due to irradiation by the primary star. At full spectral resolution of the MRS, we find atomic hydrogen recombination emission lines in the secondary star, from principal quantum levels n = 7, 8, 10, and 14.
{"title":"Toward Exoplanet Transit Spectroscopy Using JWST/MIRI’s Medium Resolution Spectrometer","authors":"Drake Deming, Guangwei Fu, Jeroen Bouwman, Daniel Dicken, Nestor Espinoza, Alistair Glasse, Thomas Greene, Sarah Kendrew, David Law, Jacob Lustig-Yaeger, Macarena Garcia Marin and Everett Schlawin","doi":"10.1088/1538-3873/ad6692","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6692","url":null,"abstract":"The Mid-Infrared Instrument Medium Resolution Spectrometer (the MRS) on JWST has potentially important advantages for transit and eclipse spectroscopy of exoplanets, including lack of saturation for bright host stars, wavelength span to longward of 20 µm, and JWST’s highest spectral resolving power. We here test the performance of the MRS for time series spectroscopy by observing the secondary eclipse of the bright stellar eclipsing binary R Canis Majoris. Our observations push the MRS into saturation at the shortest wavelength, more than for any currently known exoplanet system. We find strong charge migration between pixels that we mitigate using a custom data analysis pipeline. Our data analysis recovers much of the spatial charge migration by combining detector pixels at the group level, via weighting by the point-spread function. We achieve nearly photon-limited performance in time series data at wavelengths longward of 5.2 µm. In 2017, Snellen et al. suggested that the MRS could be used to detect carbon dioxide absorption from the atmosphere of the temperate planet orbiting Proxima Centauri. We infer that the relative spectral response of the MRS versus wavelength is sufficiently stable to make that detection feasible. As regards the secondary eclipse of this Algol-type binary, we measure the eclipse depth by summing our spectra over the wavelengths in four channels, and also measuring the eclipse depth as observed by TESS. Those eclipse depths require a temperature for the secondary star that is significantly hotter than previous observations in the optical to near-IR, probably due to irradiation by the primary star. At full spectral resolution of the MRS, we find atomic hydrogen recombination emission lines in the secondary star, from principal quantum levels n = 7, 8, 10, and 14.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936509","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 : 2024-08-04DOI: 10.1088/1538-3873/ad6210
Viraj R. Karambelkar, Mansi M. Kasliwal, Patrick Tisserand, Shreya Anand, Michael C. B. Ashley, Lars Bildsten, Geoffrey C. Clayton, Courtney C. Crawford, Kishalay De, Nicholas Earley, Matthew J. Hankins, Xander Hall, Astrid Lamberts, Ryan M. Lau, Dan McKenna, Anna Moore, Eran O. Ofek, Roger M. Smith, Roberto Soria, Jamie Soon and Tony Travouillon
We present results from a systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, using data from the Palomar Gattini IR (PGIR) survey. RCB stars are dusty, erratic variable stars presumably formed from the merger of a He-core and a CO-core white dwarf (WD). PGIR is a 30 cm J-band telescope with a 25 deg2 camera that surveys 18,000 deg2 of the northern sky (δ > −28°) at a cadence of 2 days. Using PGIR J-band lightcurves for ∼60 million stars together with mid-IR colors from WISE, we selected a sample of 530 candidate RCB stars. We obtained near-IR spectra for these candidates and identified 53 RCB stars in our sample. Accounting for our selection criteria, we find that there are a total of RCB stars in the Milky Way. Assuming typical RCB lifetimes, this corresponds to an RCB formation rate of 0.8–5 × 10−3 yr−1, consistent with observational and theoretical estimates of the He-CO WD merger rate. We searched for quasi-periodic pulsations in the PGIR lightcurves of RCB stars and present pulsation periods for 16 RCB stars. We also examined high-cadenced TESS lightcurves for RCB and the chemically similar, but dustless hydrogen-deficient carbon (dLHdC) stars. We find that dLHdC stars show variations on timescales shorter than RCB stars, suggesting that they may have lower masses than RCB stars. Finally, we identified 3 new spectroscopically confirmed and 12 candidate Galactic DY Per type stars—believed to be colder cousins of RCB star—doubling the sample of Galactic DY Per type stars.
{"title":"An Infrared Census of R Coronae Borealis Stars II—Spectroscopic Classifications and Implications for the Rate of Low-mass White Dwarf Mergers","authors":"Viraj R. Karambelkar, Mansi M. Kasliwal, Patrick Tisserand, Shreya Anand, Michael C. B. Ashley, Lars Bildsten, Geoffrey C. Clayton, Courtney C. Crawford, Kishalay De, Nicholas Earley, Matthew J. Hankins, Xander Hall, Astrid Lamberts, Ryan M. Lau, Dan McKenna, Anna Moore, Eran O. Ofek, Roger M. Smith, Roberto Soria, Jamie Soon and Tony Travouillon","doi":"10.1088/1538-3873/ad6210","DOIUrl":"https://doi.org/10.1088/1538-3873/ad6210","url":null,"abstract":"We present results from a systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, using data from the Palomar Gattini IR (PGIR) survey. RCB stars are dusty, erratic variable stars presumably formed from the merger of a He-core and a CO-core white dwarf (WD). PGIR is a 30 cm J-band telescope with a 25 deg2 camera that surveys 18,000 deg2 of the northern sky (δ > −28°) at a cadence of 2 days. Using PGIR J-band lightcurves for ∼60 million stars together with mid-IR colors from WISE, we selected a sample of 530 candidate RCB stars. We obtained near-IR spectra for these candidates and identified 53 RCB stars in our sample. Accounting for our selection criteria, we find that there are a total of RCB stars in the Milky Way. Assuming typical RCB lifetimes, this corresponds to an RCB formation rate of 0.8–5 × 10−3 yr−1, consistent with observational and theoretical estimates of the He-CO WD merger rate. We searched for quasi-periodic pulsations in the PGIR lightcurves of RCB stars and present pulsation periods for 16 RCB stars. We also examined high-cadenced TESS lightcurves for RCB and the chemically similar, but dustless hydrogen-deficient carbon (dLHdC) stars. We find that dLHdC stars show variations on timescales shorter than RCB stars, suggesting that they may have lower masses than RCB stars. Finally, we identified 3 new spectroscopically confirmed and 12 candidate Galactic DY Per type stars—believed to be colder cousins of RCB star—doubling the sample of Galactic DY Per type stars.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936508","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 : 2024-08-01DOI: 10.1088/1538-3873/ad4fe3
Szilárd Kálmán, Gyula M. Szabó and Csaba Kiss
Following the widespread practice of exoplanetary transit simulations, various presumed components of an extrasolar system can be examined in numerically simulated transits, including exomoons, rings around planets, and the deformation of exoplanets. Template signals can then be used to efficiently search for light curve features that mark specific phenomena in the data, and they also provide a basis for feasibility studies of instruments and search programs. In this paper, we present a method for exocomet transit light curve calculations using arbitrary dust distributions in transit. The calculations, spanning four distinct materials (carbon, graphite, pyroxene, and olivine), and multiple dust grain sizes (100–300 nm, 300–1000 nm, and 1000–3000 nm) encompass light curves in VRJHKL bands. We also investigated the behavior of scattering colors. We show that multicolor photometric observations are highly effective tools in the detection and characterization of exocomet transits. They provide information on the dust distribution of the comet (encoded in the light curve shape), while the color information itself can reveal the particle size change and material composition of the transiting material, in relation to the surrounding environment. We also show that the typical cometary tail can result in the wavelength dependence of the transit timing. We demonstrate that multi-wavelength observations can yield compelling evidence for the presence of exocomets in real observations.
{"title":"Exocomet Models in Transit: Light Curve Morphology in the Optical—Near Infrared Wavelength Range","authors":"Szilárd Kálmán, Gyula M. Szabó and Csaba Kiss","doi":"10.1088/1538-3873/ad4fe3","DOIUrl":"https://doi.org/10.1088/1538-3873/ad4fe3","url":null,"abstract":"Following the widespread practice of exoplanetary transit simulations, various presumed components of an extrasolar system can be examined in numerically simulated transits, including exomoons, rings around planets, and the deformation of exoplanets. Template signals can then be used to efficiently search for light curve features that mark specific phenomena in the data, and they also provide a basis for feasibility studies of instruments and search programs. In this paper, we present a method for exocomet transit light curve calculations using arbitrary dust distributions in transit. The calculations, spanning four distinct materials (carbon, graphite, pyroxene, and olivine), and multiple dust grain sizes (100–300 nm, 300–1000 nm, and 1000–3000 nm) encompass light curves in VRJHKL bands. We also investigated the behavior of scattering colors. We show that multicolor photometric observations are highly effective tools in the detection and characterization of exocomet transits. They provide information on the dust distribution of the comet (encoded in the light curve shape), while the color information itself can reveal the particle size change and material composition of the transiting material, in relation to the surrounding environment. We also show that the typical cometary tail can result in the wavelength dependence of the transit timing. We demonstrate that multi-wavelength observations can yield compelling evidence for the presence of exocomets in real observations.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936396","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 : 2024-07-24DOI: 10.1088/1538-3873/ad6105
Kaiyue Zhang
Supernova remnants are products of supernova explosions, which are usually observed in the X-ray band. However, the diffuse emission from the galactic supernova remnant G28.8+1.5 has been overlooked following initial searches for pulsars and pulsar wind nebulae. This paper presents background-subtracted imaging and spatial-resolved spectral analyses using archival XMM-Newton data to reveal unprecedented details of the diffuse emission, providing updated estimates of distance and age. For the first time, an iron overabundance is revealed and the progenitor is suggested to be 9–15 M⊙. These findings refine our understanding of G28.8+1.5 and contribute to a broader comprehension of the Galactic supernova remnant family.
超新星遗迹是超新星爆炸的产物，通常在 X 射线波段观测到。然而，在对脉冲星和脉冲星风星云进行初步搜索后，银河系超新星残余物 G28.8+1.5 的弥散发射却被忽视了。本文利用XMM-牛顿的档案数据进行了背景减缩成像和空间分辨光谱分析，揭示了弥散发射的前所未有的细节，提供了距离和年龄的最新估计值。研究首次揭示了铁元素过剩的现象，并推测其祖先为 9-15 M⊙。这些发现完善了我们对G28.8+1.5的理解，有助于更广泛地理解银河系超新星残余家族。
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Pub Date : 2024-07-23DOI: 10.1088/1538-3873/ad5d14
Olag Pratim Bordoloi, B. Ananthamoorthy, P. Shalima, Margarita Safonova, Debbijoy Bhattacharya, Yuri A. Shchekinov and Rupjyoti Gogoi
We present measurements of diffuse ultraviolet (UV) emission in the dwarf irregular galaxy Holmberg II obtained with the Ultra Violet Imaging Telescope (UVIT) instrument onboard AstroSat, India’s first multiwavelength space mission. With a spatial resolution of 1.″2–1.″6, these are the highest resolution UV observations of the galaxy to date. We find that diffuse emission accounts for ∼70.6% of the total far-ultraviolet (FUV) and for ~58.1% of the total near-ultraviolet (NUV) emission. In the FUV, this is reasonably close to the fraction reported for the SMC bar. We perform a UV–IR correlation study of the diffuse emission in this galaxy using infrared (IR) observations from the Spitzer Space Telescope and Herschel Space Observatory for selected locations, free of detectable bright point sources. The strongest positive correlation between FUV and IR is observed at 70 μm for high H i density (N(H i) > 1 × 1021 cm−2) locations, indicating that warm dust grains dominate the IR emission, in agreement with earlier studies, while NUV is better correlated with 160 μm emission associated with cold dust grains. Low H i density regions (N(H i) < 1 × 1021 cm−2), or cavities, do not show any significant UV–IR correlation except at 160 μm, implying either the presence of colder dust grains in cavities being irradiated by the general radiation field, or insufficient amount of dust. The dust scattering contribution in high H i density regions, estimated using a single scattering model with foreground dust clouds with LMC reddening, gives best-fit albedo and asymmetry factor values of α = 0.2 and g = 0.5, respectively, in reasonable agreement with the theoretical predictions for LMC dust. Our model-derived scattering optical depths in the FUV range from 0.02 to 0.12, implying the medium is optically thin. Therefore, in high H i density regions, dust scattering can be one of the sources of the observed diffuse UV emission, apart from possible contributions from H2 fluorescence. However, the diffuse UV component in H i cavities can only be explained via other mechanisms, such as two-photon emission.
我们介绍了利用印度首次多波长太空任务 AstroSat 上的紫外线成像望远镜（UVIT）仪器对矮不规则星系 Holmberg II 的漫射紫外线（UV）发射的测量结果。空间分辨率为1.″2-1.″6，这是迄今为止对该星系进行的分辨率最高的紫外观测。我们发现弥散发射占远紫外（FUV）发射总量的70.6%，占近紫外（NUV）发射总量的58.1%。在远紫外波段，这与报告的SMC条带的比例相当接近。我们利用 Spitzer 空间望远镜和 Herschel 空间天文台的红外线（IR）观测数据，对这个星系的弥散发射进行了紫外-红外相关性研究。在高 H i 密度（N(H i) > 1 × 1021 cm-2）的 70 μm 处，观察到 FUV 和 IR 之间最强的正相关性，这表明暖尘粒在红外辐射中占主导地位，这与先前的研究一致，而 NUV 与冷尘粒相关的 160 μm 辐射的相关性更好。低 H i 密度区域（N(H i) < 1 × 1021 cm-2）或空穴，除 160 μm 外，没有显示出任何明显的紫外-红外相关性，这意味着空穴中存在较冷的尘粒，受到一般辐射场的照射，或者尘粒数量不足。在高 H i 密度区域的尘埃散射贡献，是用一个具有 LMC 红化的前景尘埃云的单一散射模型估算的，得出的最佳拟合反照率和不对称系数值分别为 α = 0.2 和 g = 0.5，与 LMC 尘埃的理论预测值相当一致。我们的模型推导出的 FUV 波段散射光深度在 0.02 到 0.12 之间，这意味着介质是光学稀薄的。因此，在高H i密度区域，除了可能来自H2荧光的贡献之外，尘埃散射可能是观测到的漫射紫外辐射的来源之一。然而，H i空腔中的漫射紫外线成分只能通过其他机制来解释，例如双光子发射。
{"title":"AstroSat/UVIT Study of the Diffuse Ultraviolet Radiation in the Dwarf Galaxy Holmberg II","authors":"Olag Pratim Bordoloi, B. Ananthamoorthy, P. Shalima, Margarita Safonova, Debbijoy Bhattacharya, Yuri A. Shchekinov and Rupjyoti Gogoi","doi":"10.1088/1538-3873/ad5d14","DOIUrl":"https://doi.org/10.1088/1538-3873/ad5d14","url":null,"abstract":"We present measurements of diffuse ultraviolet (UV) emission in the dwarf irregular galaxy Holmberg II obtained with the Ultra Violet Imaging Telescope (UVIT) instrument onboard AstroSat, India’s first multiwavelength space mission. With a spatial resolution of 1.″2–1.″6, these are the highest resolution UV observations of the galaxy to date. We find that diffuse emission accounts for ∼70.6% of the total far-ultraviolet (FUV) and for ~58.1% of the total near-ultraviolet (NUV) emission. In the FUV, this is reasonably close to the fraction reported for the SMC bar. We perform a UV–IR correlation study of the diffuse emission in this galaxy using infrared (IR) observations from the Spitzer Space Telescope and Herschel Space Observatory for selected locations, free of detectable bright point sources. The strongest positive correlation between FUV and IR is observed at 70 μm for high H i density (N(H i) > 1 × 1021 cm−2) locations, indicating that warm dust grains dominate the IR emission, in agreement with earlier studies, while NUV is better correlated with 160 μm emission associated with cold dust grains. Low H i density regions (N(H i) < 1 × 1021 cm−2), or cavities, do not show any significant UV–IR correlation except at 160 μm, implying either the presence of colder dust grains in cavities being irradiated by the general radiation field, or insufficient amount of dust. The dust scattering contribution in high H i density regions, estimated using a single scattering model with foreground dust clouds with LMC reddening, gives best-fit albedo and asymmetry factor values of α = 0.2 and g = 0.5, respectively, in reasonable agreement with the theoretical predictions for LMC dust. Our model-derived scattering optical depths in the FUV range from 0.02 to 0.12, implying the medium is optically thin. Therefore, in high H i density regions, dust scattering can be one of the sources of the observed diffuse UV emission, apart from possible contributions from H2 fluorescence. However, the diffuse UV component in H i cavities can only be explained via other mechanisms, such as two-photon emission.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141770720","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 : 2024-07-21DOI: 10.1088/1538-3873/ad5fbc
Gaojing Li, Qiao Meng, Jingsong Ping, Jing Sun, Song Yang, Chenye Zhou, Shaocong Guo and Jie Wu
In radar astronomy, the digital backend and data recording system process and store echo signals in real-time, facilitating the monitoring of near-earth objects such as space debris, satellites, and asteroids. In this paper, a radar astronomy digital backend (RADB), designed for radar astronomy observation and data recording, is proposed. With a sampling rate of 1.12 GSps, the RADB accommodates various analog intermediate frequency (IF) front-ends. In addition to continuously recording echo signals, the RADB has three pulse storage modes and employs an architecture that combines a two-stage decimation (TSD) unit and a decimated pulse detection (DPD) unit. The TSD unit reduces the sampling frequency based on the bandwidth of the signal, after shifting the IF signal to the baseband. Compared to a single-stage decimation, the proposed TSD structure effectively reduces FIR resource consumption without compromising performance. Meanwhile, the DPD unit identifies pulse echo signals and selectively enables the backend to store data only when pulses are detected. This process further reduces the burden on data transmission and storage. Furthermore, the matched filtering pulse detection method in the DPD unit enhances triggering performance, particularly under weak signal conditions. Preliminary performance evaluations in a laboratory demonstrate that the TSD unit reduces data volume by 56 times, while the DPD unit achieves a further reduction of 20 times. Concurrently, a Moon reflection experiment is also conducted at the Yunnan Kunming Electromagnetic Environment Observation and Research Station by using a 29 m antenna. Analysis and processing of stored data validate the effectiveness of the proposed design.
{"title":"A Digital Backend with Pulse Detection for Radar Astronomy","authors":"Gaojing Li, Qiao Meng, Jingsong Ping, Jing Sun, Song Yang, Chenye Zhou, Shaocong Guo and Jie Wu","doi":"10.1088/1538-3873/ad5fbc","DOIUrl":"https://doi.org/10.1088/1538-3873/ad5fbc","url":null,"abstract":"In radar astronomy, the digital backend and data recording system process and store echo signals in real-time, facilitating the monitoring of near-earth objects such as space debris, satellites, and asteroids. In this paper, a radar astronomy digital backend (RADB), designed for radar astronomy observation and data recording, is proposed. With a sampling rate of 1.12 GSps, the RADB accommodates various analog intermediate frequency (IF) front-ends. In addition to continuously recording echo signals, the RADB has three pulse storage modes and employs an architecture that combines a two-stage decimation (TSD) unit and a decimated pulse detection (DPD) unit. The TSD unit reduces the sampling frequency based on the bandwidth of the signal, after shifting the IF signal to the baseband. Compared to a single-stage decimation, the proposed TSD structure effectively reduces FIR resource consumption without compromising performance. Meanwhile, the DPD unit identifies pulse echo signals and selectively enables the backend to store data only when pulses are detected. This process further reduces the burden on data transmission and storage. Furthermore, the matched filtering pulse detection method in the DPD unit enhances triggering performance, particularly under weak signal conditions. Preliminary performance evaluations in a laboratory demonstrate that the TSD unit reduces data volume by 56 times, while the DPD unit achieves a further reduction of 20 times. Concurrently, a Moon reflection experiment is also conducted at the Yunnan Kunming Electromagnetic Environment Observation and Research Station by using a 29 m antenna. Analysis and processing of stored data validate the effectiveness of the proposed design.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737745","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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