The Astrophysical Journal Letters最新文献_第9页

A Novel q-PED Method: Precise Physical Properties of a Merger-origin Binary Cepheid OGLE-LMC-CEP-1347

The Astrophysical Journal Letters Pub Date : 2025-03-10 DOI: 10.3847/2041-8213/adb96b

Felipe Espinoza-Arancibia and Bogumił Pilecki

{"title":"A Novel q-PED Method: Precise Physical Properties of a Merger-origin Binary Cepheid OGLE-LMC-CEP-1347","authors":"Felipe Espinoza-Arancibia and Bogumił Pilecki","doi":"10.3847/2041-8213/adb96b","DOIUrl":"https://doi.org/10.3847/2041-8213/adb96b","url":null,"abstract":"Recently, a double-lined binary classical Cepheid, OGLE-LMC-CEP-1347, was discovered with the orbital period (Porb = 59 days), 5 times shorter than that of any binary Cepheid known before. The expected mass of the Cepheid was below 3.5 M⊙, which, if confirmed, would also probe uncharted territory. The system configuration also pointed to the Cepheid being a merger. We present a novel method for determining precise physical parameters of binary Cepheids using both theory and observations. This q-PED method combines the measured mass ratio (q), pulsation (P), and evolutionary (E) models and the known distance (D), supplemented with multiband photometry. Applying it, we determined the mass of the Cepheid to be 3.41 ± 0.08 M⊙ and its radius to be 13.65 ± 0.27 R⊙, and the companion's mass to be 1.89 ± 0.04 M⊙ and radius to be 12.51 ± 0.62 R⊙. With the current configuration, the apparent evolutionary age difference of almost 1 Gyr between the components strongly favors the Cepheid merger origin scenario. If so, the actual age of the Cepheid would be 1.09 Gyr, on the edge of Population II stars, indicating that a significant fraction of Cepheids may be much older than typically assumed. We also applied our method to an eclipsing binary Cepheid OGLE-LMC-CEP-1812 with accurately determined physical parameters, obtaining a close agreement, which confirmed our method’s reliability.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143589863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Time-resolved High-resolution Spectroscopic Analysis of Ionized Calcium and Dynamical Processes in the Ultra-hot Jupiter HAT-P-70 b

The Astrophysical Journal Letters Pub Date : 2025-03-07 DOI: 10.3847/2041-8213/adb70d

Adam B. Langeveld, Emily K. Deibert, Mitchell E. Young, Ernst de Mooij, Ray Jayawardhana, Chris Simpson, Jake D. Turner and Laura Flagg

{"title":"A Time-resolved High-resolution Spectroscopic Analysis of Ionized Calcium and Dynamical Processes in the Ultra-hot Jupiter HAT-P-70 b","authors":"Adam B. Langeveld, Emily K. Deibert, Mitchell E. Young, Ernst de Mooij, Ray Jayawardhana, Chris Simpson, Jake D. Turner and Laura Flagg","doi":"10.3847/2041-8213/adb70d","DOIUrl":"https://doi.org/10.3847/2041-8213/adb70d","url":null,"abstract":"We present the first transmission spectroscopy study of an exoplanet atmosphere with the high-resolution mode of the new Gemini High-resolution Optical SpecTrograph (GHOST) instrument at the Gemini South Observatory. We observed one transit of HAT-P-70 b—an ultra-hot Jupiter with an inflated radius—and made a new detection of the infrared Ca ii triplet in its transmission spectrum. The depth of the strongest line implies that a substantial amount of Ca ii extends to at least 47% above the bulk planetary radius. The triplet lines are blueshifted between ∼3 to 5 km s−1, indicative of strong dayside-to-nightside winds common on highly irradiated gas giants. Comparing the transmission spectrum with atmospheric models that incorporate non–local thermodynamic equilibrium effects suggests that the planetary mass is likely between 1 and 2 MJ, much lighter than the upper limit previously derived from radial velocity measurements. Importantly, thanks to the high signal-to-noise ratio achieved by GHOST/Gemini South, we are able to measure the temporal variation of these signals. Absorption depths and velocity offsets of the individual Ca ii lines remain mostly consistent across the transit, except for the egress phases, where weaker absorption and stronger blueshifts are observed, highlighting the atmospheric processes within the trailing limb alone. Our study demonstrates the ability of GHOST to make time-resolved detections of individual spectral lines, providing valuable insights into the 3D nature of exoplanet atmospheres by probing different planetary longitudes as the tidally locked planet rotates during the transit.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143575250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

HCN and C2H2 in the Atmosphere of a T8.5+T9 Brown Dwarf Binary

The Astrophysical Journal Letters Pub Date : 2025-03-07 DOI: 10.3847/2041-8213/adb4ec

Elisabeth C. Matthews, Paul Mollière, Helena Kühnle, Polychronis Patapis, Niall Whiteford, Matthias Samland, Pierre-Olivier Lagage, Rens Waters, Shang-Min Tsai, Kevin Zahnle, Manuel Guedel, Thomas Henning, Bart Vandenbussche, Olivier Absil, Ioannis Argyriou, David Barrado, Alain Coulais, Adrian M. Glauser, Goran Olofsson, John P. Pye, Daniel Rouan, Pierre Royer, Ewine F. van Dishoeck, T. P. Ray and Göran Östlin

{"title":"HCN and C2H2 in the Atmosphere of a T8.5+T9 Brown Dwarf Binary","authors":"Elisabeth C. Matthews, Paul Mollière, Helena Kühnle, Polychronis Patapis, Niall Whiteford, Matthias Samland, Pierre-Olivier Lagage, Rens Waters, Shang-Min Tsai, Kevin Zahnle, Manuel Guedel, Thomas Henning, Bart Vandenbussche, Olivier Absil, Ioannis Argyriou, David Barrado, Alain Coulais, Adrian M. Glauser, Goran Olofsson, John P. Pye, Daniel Rouan, Pierre Royer, Ewine F. van Dishoeck, T. P. Ray and Göran Östlin","doi":"10.3847/2041-8213/adb4ec","DOIUrl":"https://doi.org/10.3847/2041-8213/adb4ec","url":null,"abstract":"T-type brown dwarfs present an opportunity to explore atmospheres teeming with molecules such as H2O, CH4, and NH3, which exhibit a wealth of absorption features in the mid-infrared. With JWST, we can finally explore this chemistry in detail, including for the coldest brown dwarfs that were not yet discovered in the Spitzer era. This allows precise derivations of the molecular abundances, which in turn inform our understanding of vertical transport in these atmospheres and can provide clues about the formation of cold brown dwarfs and exoplanets. This study presents the first JWST/MRS mid-IR spectrum (R ∼ 1500–3000) of a T dwarf: the T8.5+T9 brown dwarf binary WISE J045853.90+643451.9. We fit the spectrum using a parameterized P–T profile and free molecular abundances (i.e., a retrieval analysis), treating the binary as unresolved. We find a good fit with a cloud-free atmosphere and identify H2O, CH4, and NH3 features. Moreover, we make the first detections of HCN and C2H2 (at 13.4σ and 9.5σ respectively) in any brown dwarf atmosphere. The detection of HCN suggests intense vertical mixing (Kzz ∼ 1011 cm2 s−1), challenging previous literature derivations of Kzz values for T-type brown dwarfs. Even more surprising is the C2H2 detection, which cannot be explained with existing atmospheric models for isolated objects. This result challenges model assumptions about vertical mixing and/or our understanding of the C2H2 chemical network, or might hint towards more complex atmospheric processes such as magnetic fields driving aurorae or lightning driving ionization. These findings open a new frontier in studying carbon chemistry within brown dwarf atmospheres.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143575248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Mapping the Merging Zone of Late Infall in the AB Aur Planet-forming System 绘制AB Aur行星形成系统晚期衰减的合并区地图

The Astrophysical Journal Letters Pub Date : 2025-03-06 DOI: 10.3847/2041-8213/adb7d5

Jessica Speedie, Ruobing Dong, Richard Teague, Dominique Segura-Cox, Jaime E. Pineda, Josh Calcino, Cristiano Longarini, Cassandra Hall, Ya-Wen Tang, Jun Hashimoto, Teresa Paneque-Carreño, Giuseppe Lodato and Bennedetta Veronesi

{"title":"Mapping the Merging Zone of Late Infall in the AB Aur Planet-forming System","authors":"Jessica Speedie, Ruobing Dong, Richard Teague, Dominique Segura-Cox, Jaime E. Pineda, Josh Calcino, Cristiano Longarini, Cassandra Hall, Ya-Wen Tang, Jun Hashimoto, Teresa Paneque-Carreño, Giuseppe Lodato and Bennedetta Veronesi","doi":"10.3847/2041-8213/adb7d5","DOIUrl":"https://doi.org/10.3847/2041-8213/adb7d5","url":null,"abstract":"Late infall events challenge the traditional view that planet formation occurs without external influence. Here we present deep Atacama Large Millimeter/submillimeter Array 12CO J = 2–1 and SO JN = 56–45 observations toward AB Aurigae (AB Aur), a Class II disk system with strong signs of gravitational instability and ongoing planet formation. By applying Keplerian and anti-Keplerian masks, we separate disk-like and non-disk-like motions of 12CO, considering the two outputs as the “disk” and “exo-disk” (out of disk) emission components, respectively. The disk component of 12CO extends to ∼1600 au in radius and exhibits a stunningly rich architecture of global spiral structure. The exo-disk emission consists predominantly of three spiral structures—S1, S2, and S3—whose projections are cospatial with the disk. We successfully reproduce their trajectories with a ballistic accretion flow model, finding that S1 and S2 (both redshifted) are infalling toward the disk from in front, and S3 (blueshifted) is infalling from behind. Where the terminal ends of S1 and S2 become indistinguishable from the disk, we observe a brightness peak in SO emission 2.5× the azimuthal average of a background SO ring. This merging zone lies within a relatively confined region 15°–100∘ east of north, and between ∼150 and 300 au from the star, at scales relevant to where planet candidates have been previously identified. The AB Aur system provides a unified picture of late infall inducing replenishment of the disk, triggering gravitational instability, and modifying the conditions of forming planets.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143569491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

In Situ Formation of Star Clusters at z > 7 via Galactic Disk Fragmentation: Shedding Light on Ultracompact Clusters and Overmassive Black Holes Seen by JWST

The Astrophysical Journal Letters Pub Date : 2025-03-06 DOI: 10.3847/2041-8213/adadfe

Lucio Mayer, Floor van Donkelaar, Matteo Messa, Pedro R. Capelo and Angela Adamo

{"title":"In Situ Formation of Star Clusters at z > 7 via Galactic Disk Fragmentation: Shedding Light on Ultracompact Clusters and Overmassive Black Holes Seen by JWST","authors":"Lucio Mayer, Floor van Donkelaar, Matteo Messa, Pedro R. Capelo and Angela Adamo","doi":"10.3847/2041-8213/adadfe","DOIUrl":"https://doi.org/10.3847/2041-8213/adadfe","url":null,"abstract":"We investigate the nature of star formation in gas-rich galaxies at z > 7 forming in a markedly overdense region, in the vicinity of a massive virialized halo already exceeding 1012M⊙, through the use of the very-high-resolution cosmological hydrodynamical simulation MassiveBlackPS with a spatial resolution of 2 pc. We find that not only the primary galaxy but also the lower-mass companion galaxies rapidly develop massive self-gravitating compact gas disks, less than 500 pc in size, which undergo fragmentation by gravitational instability into very massive bound clumps. Star formation proceeds fast in the clumps, which quickly turn into compact star clusters with masses in the range 105–108M⊙ and typical half-mass radii of a few parsec, reaching characteristic densities above 105M⊙ pc−2. The properties of the clusters in the lowest-mass galaxy bear a striking resemblance to those recently discovered by the James Webb Space Telescope (JWST) in the lensed Cosmic Gems arc system at z = 10.2. We argue that, due to their extremely high stellar densities, intermediate-mass black holes would form rapidly inside the clusters, which would then swiftly sink and merge on their way to the galactic nucleus, easily growing into a 107M⊙ supermassive black hole (SMBH). Due to the high fractional mass contribution of clusters to the stellar mass of the galaxies, in the range 20%–40%, the central SMBH would comprise more than 10% of the mass of its host galaxy, naturally explaining the overmassive SMBHs discovered by JWST at z > 6.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143560811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

PSR J1922+37: a 1.9 s Pulsar Discovered in the Direction of the Old Open Cluster NGC 6791

The Astrophysical Journal Letters Pub Date : 2025-03-06 DOI: 10.3847/2041-8213/adb9c4

Xiao-Jin Liu, Rahul Sengar, Matthew Bailes, Ralph P. Eatough, Jianping Yuan, Na Wang, Weiwei Zhu, Lu Zhou, He Gao, Zong-Hong Zhu and Xing-Jiang Zhu

引用次数: 0

Measuring the Mean Free Path of H i Ionizing Photons at 3.2 ≤ z ≤ 4.6 with DESI Y1 Quasars

The Astrophysical Journal Letters Pub Date : 2025-03-05 DOI: 10.3847/2041-8213/adb48f

Anning Gao, J. Xavier Prochaska, Zheng Cai, Siwei Zou, Cheng Zhao, Zechang Sun, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. de la Macorra, Arjun Dey, P. Doel, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, K. Honscheid, S. Juneau, A. Kremin, P. Martini, A. Meisner, R. Miquel, J. Moustakas, A. Muñoz-Gutiérrez, J. A. Newman, I. Pérez-Ràfols, G. Rossi, E. Sanchez, M. Schubnell, D. Sprayberry, G. Tarlé, B. A. Weaver and H. Zou

{"title":"Measuring the Mean Free Path of H i Ionizing Photons at 3.2 ≤ z ≤ 4.6 with DESI Y1 Quasars","authors":"Anning Gao, J. Xavier Prochaska, Zheng Cai, Siwei Zou, Cheng Zhao, Zechang Sun, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. de la Macorra, Arjun Dey, P. Doel, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, K. Honscheid, S. Juneau, A. Kremin, P. Martini, A. Meisner, R. Miquel, J. Moustakas, A. Muñoz-Gutiérrez, J. A. Newman, I. Pérez-Ràfols, G. Rossi, E. Sanchez, M. Schubnell, D. Sprayberry, G. Tarlé, B. A. Weaver and H. Zou","doi":"10.3847/2041-8213/adb48f","DOIUrl":"https://doi.org/10.3847/2041-8213/adb48f","url":null,"abstract":"The mean free path of ionizing photons in the intergalactic medium (IGM; ) is a crucial quantity in modeling the ionization state of the IGM and the extragalactic ultraviolet background, and it is widely used in hydrodynamical simulations of galaxies and reionization. We construct the largest quasar spectrum data set to date—12,595 signal-to-noise ratio > 3 spectra—using the Y1 observations of the Dark Energy Spectroscopic Instrument, to make the most precise model-independent measurement of the mean free path at 3.2 ≤ z ≤ 4.6. By stacking the spectra in 17 redshift bins and modeling the Lyman-continuum profile, we get a redshift evolution at 2 ≤ z ≤ 5, which is much shallower than the previous estimate, . We then explore the sources of systematic bias, including the choice of the intrinsic quasar continuum, the consideration of Lyman-series opacity and Lyman-limit opacity evolution, and the definition of . Combining our results with estimates of at higher redshifts, we conclude at high confidence that the evolution in steepens at z ≈ 5. We interpret this inflection as the transition from the end of H i reionization to a fully ionized plasma that characterizes the IGM of the past ∼10 billion yr.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143560810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Interpreting the Extremely Diffuse Stellar Distribution of the Nube Galaxy through Fuzzy Dark Matter

The Astrophysical Journal Letters Pub Date : 2025-03-05 DOI: 10.3847/2041-8213/adb7da

Yu-Ming Yang, Zhao-Chen Zhang, Xiao-Jun Bi and Peng-Fei Yin

引用次数: 0

Constraints on the Fractional Changes of the Fundamental Constants at a Look-back Time of 2.5 Myr

The Astrophysical Journal Letters Pub Date : 2025-03-05 DOI: 10.3847/2041-8213/adb843

Renzhi Su, 仁智苏, Tao An, Stephen J. Curran, Michael P. Busch, Minfeng Gu and Di Li

引用次数: 0

Orbital Inclination of Astrometric Binaries and the Dearth of Face-on Orbits in Gaia DR3 Solutions

The Astrophysical Journal Letters Pub Date : 2025-03-04 DOI: 10.3847/2041-8213/adb840

Valeri V. Makarov

引用次数: 0