The Astrophysical Journal Letters最新文献

Electron Densities of Transition Region Loops Derived from IRIS O iv Spectral Data 根据 IRIS O iv 光谱数据推导出的过渡区环路电子密度

The Astrophysical Journal Letters Pub Date : 2024-04-15 DOI: 10.3847/2041-8213/ad3d5e

Shiyu Liang, Ziyuan Wang, Zhenghua Huang, Hengyuan Wei, H. Fu, Ming Xiong, Lidong Xia

{"title":"Electron Densities of Transition Region Loops Derived from IRIS O iv Spectral Data","authors":"Shiyu Liang, Ziyuan Wang, Zhenghua Huang, Hengyuan Wei, H. Fu, Ming Xiong, Lidong Xia","doi":"10.3847/2041-8213/ad3d5e","DOIUrl":"https://doi.org/10.3847/2041-8213/ad3d5e","url":null,"abstract":"\u0000 Loops are fundamental structures in the magnetized atmosphere of the Sun. Their physical properties are crucial for understanding the nature of the solar atmosphere. Transition region loops are relatively dynamic and their physical properties have not yet been fully understood. With spectral data of the line pair of O iv 1399.8 Å and 1401.2 Å (\u0000 \u0000\u0000\u0000 \u0000 \u0000 \u0000 T\u0000 \u0000 \u0000 max\u0000 \u0000 \u0000 =\u0000 1.4\u0000 ×\u0000 \u0000 \u0000 10\u0000 \u0000 \u0000 5\u0000 \u0000 \u0000 \u0000 \u0000 K) of 23 transition region loops obtained by IRIS, we carry out the first systematic analyses to their loop lengths (L), electron densities (n\u0000 \u0000 e\u0000 ), and effective temperatures. We found electron densities, loop lengths, and effective temperatures of these loops are in the ranges of 8.9 × 109–3.5 × 1011 cm−3, 8–30 Mm, and 1.9 × 105–1.3 × 106 K, respectively. At a significant level of 90%, regression analyses show that the relationship between electron densities and loop lengths is n\u0000 \u0000 e\u0000 [cm−3] ∝ (L[Mm])−0.78±0.42, while the dependences of electron densities on effective temperatures and that on the line intensities are not obvious. These observations demonstrate that transition region loops are significantly different than their coronal counterparts. Further studies on the theoretical aspect based on the physical parameters obtained here are of significance for understanding the nature of transition region loops.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"2 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140702411","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

Stellar Black Holes Can “Stretch” Supermassive Black Hole Accretion Disks 恒星黑洞能 "拉伸 "超大质量黑洞吸积盘

The Astrophysical Journal Letters Pub Date : 2024-04-11 DOI: 10.3847/2041-8213/ad3c3f

Shuying Zhou, M. Sun, Tong Liu, Jian-Min Wang, Jun-Xian Wang, Yongquan Xue

{"title":"Stellar Black Holes Can “Stretch” Supermassive Black Hole Accretion Disks","authors":"Shuying Zhou, M. Sun, Tong Liu, Jian-Min Wang, Jun-Xian Wang, Yongquan Xue","doi":"10.3847/2041-8213/ad3c3f","DOIUrl":"https://doi.org/10.3847/2041-8213/ad3c3f","url":null,"abstract":"\u0000 Stellar black holes (sBHs) are widely believed to exist in the accretion disks of active galactic nuclei (AGNs). Previous studies often focus on the transient emission produced by embedded sBHs. Here, we explore the possible observational consequences of an AGN accretion disk that contains a population of accreting sBHs. Embedded accreting sBHs change the effective temperature distribution of the AGN accretion disk by heating gas in the outer regions. Two possible observational consequences are presented. First, the spectral energy distribution has a turnover feature at ∼4700 Å when the supermassive black hole mass is ∼108\u0000 M\u0000 ⊙, which can help explain the observed shallow spectral shape at wavelengths >5000 Å for the Sloan Digital Sky Survey quasar composite spectrum. Second, the half-light radius of a given relatively long wavelength is significantly larger than for an AGN disk without sBHs, which can be tested by microlensing observations. With appropriate sBH distributions, the model can be reconciled with quasar microlensing disk sizes. We propose that the half-light radius–wavelength relation can be utilized to investigate the distributions of embedded sBHs in AGN accretion disks.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"52 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140713939","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: 1

Surface Charging of Jupiter’s Moon Europa 木星卫星木卫二的表面充电现象

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad251e

Sachin A. Reddy, T. Nordheim, Camilla D. K. Harris

引用次数: 0

Measuring Tracers of Planet Formation in the Atmosphere of WASP-77A b: Substellar O/H and C/H Ratios, with a Stellar C/O Ratio and a Potentially Superstellar Ti/H Ratio 测量 WASP-77A b 大气中的行星形成示踪物：亚恒星 O/H 和 C/H 比率，以及恒星 C/O 比率和潜在的超恒星 Ti/H 比率

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad2000

B. Edwards, Q. Changeat

{"title":"Measuring Tracers of Planet Formation in the Atmosphere of WASP-77A b: Substellar O/H and C/H Ratios, with a Stellar C/O Ratio and a Potentially Superstellar Ti/H Ratio","authors":"B. Edwards, Q. Changeat","doi":"10.3847/2041-8213/ad2000","DOIUrl":"https://doi.org/10.3847/2041-8213/ad2000","url":null,"abstract":"\u0000 We present a comprehensive atmospheric retrieval study of the hot Jupiter WASP-77A b using eclipse observations from the Hubble Space Telescope (HST) and JWST. Using atmospheric retrievals, the spectral features of H2O, CO, and TiO are identified, with volume mixing ratios estimated at log10(VMR) = −4.40\u0000 \u0000\u0000\u0000 \u0000 \u0000 \u0000 \u0000 −\u0000 0.11\u0000 \u0000 \u0000 +\u0000 0.14\u0000 \u0000 \u0000 \u0000 \u0000 , −4.44\u0000 \u0000\u0000\u0000 \u0000 \u0000 \u0000 \u0000 −\u0000 0.28\u0000 \u0000 \u0000 +\u0000 0.34\u0000 \u0000 \u0000 \u0000 \u0000 , and −6.40\u0000 \u0000\u0000\u0000 \u0000 \u0000 \u0000 \u0000 −\u0000 0.23\u0000 \u0000 \u0000 +\u0000 0.22\u0000 \u0000 \u0000 \u0000 \u0000 , respectively. We derive the atmospheric C-to-O ratio—a key planetary formation tracer—to be C/O = 0.54 ± 0.12, which is consistent with both the stellar host value and previous studies of the planet’s atmosphere, suggesting a relatively close-in formation. Computing other elemental ratios (i.e., C/H, O/H, and Ti/H), we conclude that the general enrichment of the atmosphere (i.e., metallicity) is substellar, depleted in C and O, but that Ti appears slightly superstellar. A low C and O content could be obtained, in combination with a stellar C/O ratio if the planet formed outside of the CO2 snow line before migrating inwards. Meanwhile, a superstellar Ti/H could be obtained by late contamination from refractory rich planetesimals. While broadly in agreement with previous works, we do find some differences and discuss these while also highlighting the need for homogeneous analyses when comparative exoplanetology is conducted.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139820273","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

The Progenitor and Central Engine of a Peculiar GRB 230307A 奇特 GRB 230307A 的祖先和中心引擎

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad22e2

ZhaoWei Du, H. Lü, Yong Yuan, Xing Yang, E. Liang

{"title":"The Progenitor and Central Engine of a Peculiar GRB 230307A","authors":"ZhaoWei Du, H. Lü, Yong Yuan, Xing Yang, E. Liang","doi":"10.3847/2041-8213/ad22e2","DOIUrl":"https://doi.org/10.3847/2041-8213/ad22e2","url":null,"abstract":"\u0000 Recently, a lack of supernova-associated with long-duration gamma-ray burst (GRB 230307A) at such a low redshift z = 0.065, but associated with a possible kilonova emission, has attracted great attention. Its heavy element nucleosynthesis and the characteristic of soft X-ray emission suggest that the central engine of GRB 230307A is a magnetar that is originated from a binary compact star merger. The calculated lower value of ε ∼ 0.05 suggests that GRB 230307A seems to have an ambiguous progenitor. The lower value of f\u0000 eff = 1.23 implies that GRB 230307A is not likely to be from the effect of “tip of iceberg.” We adopt the magnetar central engine model to fit the observed soft X-ray emission with varying efficiency and find that the parameter constraints of the magnetar falls into a reasonable range, i.e., B < 9.4 × 1015 G and P < 2.5 ms for Γsat = 103, and B < 3.6 × 1015 G and P < 1.05 ms for Γsat = 104. Whether the progenitor of GBR 230307A is from the mergers of neutron star–white dwarf (NS–WD) or neutron star–neutron star (NS–NS) remains unknown. The difference of GW radiation between NS–NS merger and NS–WD merger may be a probe to distinguish the progenitor of GRB 230307A-like events in the future.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"110 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139876553","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

Surface Charging of Jupiter’s Moon Europa 木星卫星木卫二的表面充电现象

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad251e

Sachin A. Reddy, T. Nordheim, Camilla D. K. Harris

引用次数: 0

Classifying Optical (Out)bursts in Cataclysmic Variables: The Distinct Observational Characteristics of Dwarf Novae, Micronovae, Stellar Flares, and Magnetic Gating 大灾变变星的光学（爆发）分类：矮新星、微新星、恒星耀斑和磁门的不同观测特征

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad243c

K. Iłkiewicz, Simone Scaringi, Martina Veresvarska, D. de Martino, Colin Littlefield, Christian Knigge, J. Paice, Anwesha Sahu

{"title":"Classifying Optical (Out)bursts in Cataclysmic Variables: The Distinct Observational Characteristics of Dwarf Novae, Micronovae, Stellar Flares, and Magnetic Gating","authors":"K. Iłkiewicz, Simone Scaringi, Martina Veresvarska, D. de Martino, Colin Littlefield, Christian Knigge, J. Paice, Anwesha Sahu","doi":"10.3847/2041-8213/ad243c","DOIUrl":"https://doi.org/10.3847/2041-8213/ad243c","url":null,"abstract":"\u0000 Cataclysmic variables can experience short optical brightenings, which are commonly attributed to phenomena such as dwarf novae outbursts, micronovae, donor flares, or magnetic gating bursts. Since these events exhibit similar observational characteristics, their identification has often been ambiguous. In particular, magnetic gating bursts and micronovae have been suggested as alternative interpretations of the same phenomena. Here we show that the timescales and energies separate the optical brightenings into separate clusters consistent with their different classifications. This suggests that micronovae and magnetic gating bursts are in fact separate phenomena. Based on our findings, we develop diagnostic diagrams that can distinguish between these bursts/flares based on their properties. We demonstrate the effectiveness of this approach on observations of a newly identified intermediate polar, CTCV J0333-4451, which we classify as a magnetic gating system. CTCV J0333-4451 is the third highest spin-to-orbital period ratio intermediate polar with magnetic gating, suggesting that these bursts are common among these rare systems.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"433 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139824874","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

Classifying Optical (Out)bursts in Cataclysmic Variables: The Distinct Observational Characteristics of Dwarf Novae, Micronovae, Stellar Flares, and Magnetic Gating 大灾变变星的光学（爆发）分类：矮新星、微新星、恒星耀斑和磁门的不同观测特征

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad243c

K. Iłkiewicz, Simone Scaringi, Martina Veresvarska, D. de Martino, Colin Littlefield, Christian Knigge, J. Paice, Anwesha Sahu

{"title":"Classifying Optical (Out)bursts in Cataclysmic Variables: The Distinct Observational Characteristics of Dwarf Novae, Micronovae, Stellar Flares, and Magnetic Gating","authors":"K. Iłkiewicz, Simone Scaringi, Martina Veresvarska, D. de Martino, Colin Littlefield, Christian Knigge, J. Paice, Anwesha Sahu","doi":"10.3847/2041-8213/ad243c","DOIUrl":"https://doi.org/10.3847/2041-8213/ad243c","url":null,"abstract":"\u0000 Cataclysmic variables can experience short optical brightenings, which are commonly attributed to phenomena such as dwarf novae outbursts, micronovae, donor flares, or magnetic gating bursts. Since these events exhibit similar observational characteristics, their identification has often been ambiguous. In particular, magnetic gating bursts and micronovae have been suggested as alternative interpretations of the same phenomena. Here we show that the timescales and energies separate the optical brightenings into separate clusters consistent with their different classifications. This suggests that micronovae and magnetic gating bursts are in fact separate phenomena. Based on our findings, we develop diagnostic diagrams that can distinguish between these bursts/flares based on their properties. We demonstrate the effectiveness of this approach on observations of a newly identified intermediate polar, CTCV J0333-4451, which we classify as a magnetic gating system. CTCV J0333-4451 is the third highest spin-to-orbital period ratio intermediate polar with magnetic gating, suggesting that these bursts are common among these rare systems.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"30 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139884533","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

True Pair-instability Supernova Descendant: Implications for the First Stars’ Mass Distribution 真正的对不稳定超新星后裔：第一代恒星质量分布的含义

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad2466

I. Koutsouridou, Stefania Salvadori, Á. Skúladóttir

{"title":"True Pair-instability Supernova Descendant: Implications for the First Stars’ Mass Distribution","authors":"I. Koutsouridou, Stefania Salvadori, Á. Skúladóttir","doi":"10.3847/2041-8213/ad2466","DOIUrl":"https://doi.org/10.3847/2041-8213/ad2466","url":null,"abstract":"\u0000 The initial mass function (IMF) of the first Population III (Pop III) stars remains a persistent mystery. Their predicted massive nature implies the existence of stars exploding as pair-instability supernovae (PISNe), but no observational evidence had been found. Now, the LAMOST survey claims to have discovered a pure PISN descendant, J1010+2358, at [Fe/H] = − 2.4. Here we confirm that a massive 250–260 M\u0000 ⊙ PISN is needed to reproduce the abundance pattern of J1010+2358. However, the PISN contribution can be as low as 10%, since key elements are missing to discriminate between scenarios. We investigate the implications of this discovery for the Pop III IMF, by statistical comparison with the predictions of our cosmological galaxy formation model, NEFERTITI. First, we show that the nondetection of mono-enriched PISN descendants at [Fe/H] < − 2.5 allows us to exclude (i) a flat IMF at a 90% confidence level; and (ii) a Larson-type IMF with characteristic mass m\u0000 ch/M\u0000 ⊙ > 191.16x − 132.44, where x is the slope, at a 75% confidence level. Second, we show that if J1010+2358 has only inherited <70% of its metals from a massive PISN, no further constraints can be put on the Pop III IMF. If, instead, J1010+2358 will be confirmed to be a nearly pure (>90%) PISN descendant, it will offer strong and complementary constraints on the Pop III IMF, excluding the steepest and bottom-heaviest IMFs: m\u0000 ch/M\u0000 ⊙ < 143.21x − 225.94. Our work shows that even a single detection of a pure PISN descendant can be crucial to our understanding of the mass distribution of the first stars.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"29 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139826527","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

Passing Stars as an Important Driver of Paleoclimate and the Solar System’s Orbital Evolution 过路恒星是古气候和太阳系轨道演变的重要驱动力

The Astrophysical Journal Letters Pub Date : 2024-02-01 DOI: 10.3847/2041-8213/ad24fb

N. Kaib, S. Raymond

{"title":"Passing Stars as an Important Driver of Paleoclimate and the Solar System’s Orbital Evolution","authors":"N. Kaib, S. Raymond","doi":"10.3847/2041-8213/ad24fb","DOIUrl":"https://doi.org/10.3847/2041-8213/ad24fb","url":null,"abstract":"\u0000 Reconstructions of the paleoclimate indicate that ancient climatic fluctuations on Earth are often correlated with variations in its orbital elements. However, the chaos inherent in the solar system’s orbital evolution prevents numerical simulations from confidently predicting Earth’s past orbital evolution beyond 50–100 Myr. Gravitational interactions among the Sun’s planets and asteroids are believed to set this limiting time horizon, but most prior works approximate the solar system as an isolated system and neglect our surrounding Galaxy. Here we present simulations that include the Sun’s nearby stellar population, and we find that close-passing field stars alter our entire planetary system’s orbital evolution via their gravitational perturbations on the giant planets. This shortens the timespan over which Earth’s orbital evolution can be definitively known by a further ∼10%. In particular, in simulations that include an exceptionally close passage of the Sun-like star HD 7977 2.8 Myr ago, new sequences of Earth’s orbital evolution become possible in epochs before ∼50 Myr ago, which includes the Paleocene–Eocene Thermal Maximum. Thus, simulations predicting Earth’s past orbital evolution before ∼50 Myr ago must consider the additional uncertainty from passing stars, which can open new regimes of past orbital evolution not seen in previous modeling efforts.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"37 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139813679","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