Monthly Notices of the Royal Astronomical Society: Letters最新文献_第10页

The stellar thermal wind as a consequence of oblateness 由于扁率而产生的恒星热风

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-18 DOI: 10.1093/mnrasl/slad121

L. Matilsky

{"title":"The stellar thermal wind as a consequence of oblateness","authors":"L. Matilsky","doi":"10.1093/mnrasl/slad121","DOIUrl":"https://doi.org/10.1093/mnrasl/slad121","url":null,"abstract":"\u0000 In many rotating fluids, the lowest-order force balance is between gravity, pressure, and rotational acceleration (‘GPR’ balance). Terrestrial GPR balance takes the form of geostrophy and hydrostasy, which together yield the terrestrial thermal wind equation. By contrast, stellar GPR balance is an oblateness equation, which determines the departures of the thermal variables from spherical symmetry; its curl yields the ‘stellar thermal wind equation.’ In this sense, the stellar thermal wind should be viewed not as a consequence of geostrophy, but of baroclinicity in the oblateness. Here we treat the full stellar oblateness, including the thermal wind, using pressure coordinates. We derive the generalised stellar thermal wind equation and identify the parameter regime for which it holds. In the case of the Sun, not considering the full oblateness has resulted in conflicting calculations of the theoretical aspherical temperature anomaly. We provide new calculation here and find that the baroclinic anomaly is ∼3–60 times smaller than the barotropic anomaly. Thus, the anomaly from the thermal wind may not be measurable helioseismically; but if measurement were possible, this would potentially yield a new way to bracket the depth of the solar tachocline.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"28 9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89097441","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 luminous, hard state can’t be MAD 发光、坚硬的状态不可能是MAD

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-17 DOI: 10.1093/mnrasl/slad099

P. C. Fragile, K. Chatterjee, A. Ingram, M. Middleton

引用次数: 0

A giant radio galaxy with three cycles of episodic jet activity from LoTSS DR2 一个巨大的射电星系，从LoTSS DR2有三个周期的间歇性喷流活动

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-17 DOI: 10.1093/mnrasl/slad100

Kshitij Chavan, P. Dabhade, D. Saikia

引用次数: 1

The dual nature of the tidal tails of NGC 5904 (M5) NGC 5904 (M5)潮尾的双重性质

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-14 DOI: 10.1093/mnrasl/slad098

A. Piatti

{"title":"The dual nature of the tidal tails of NGC 5904 (M5)","authors":"A. Piatti","doi":"10.1093/mnrasl/slad098","DOIUrl":"https://doi.org/10.1093/mnrasl/slad098","url":null,"abstract":"\u0000 The tangential velocity dispersion of stars belonging to the Milky Way globular cluster’s tidal tails has recently been found from N-body simulations to be a parameter that distinguishes between cored and cuspy profiles of low-mass dwarf galaxy dark matter subhaloes where that globular cluster formed, and the in-situ formation scenario. In this context, we discovered that M5’s tidal tails are composed by stars at two different metallicity regimes ([Fe/H] ∼ -1.4 dex and -2.0 dex). The more metal-rich tidal tail stars are of the same metal content than M5’s members and have a tangential velocity dispersion that coincides with the predicted value for a cuspy formation scenario (subhalo mass ∼ 109 M⊙). The more metal-poor stars, that are found along the entire M5 tidal tails and have similar distributions to their more metal-rich counterparts in the M5 colour-magnitude diagram and orbit trajectory, have a tangential velocity dispersion that refers to a cored subhalo (mass ∼ 109 M⊙) or an in-situ formation scenario. In order to reconcile the dual distribution of M5 tidal tail stars, in kinematics and chemistry, we propose that M5 collided with another more metal-poor and less massive globular cluster anytime before or after it was accreted into the Milky Way.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80021121","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

Analysis of the possible satellite contamination in LAMOST-MRS spectra LAMOST-MRS光谱中可能的卫星污染分析

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-10 DOI: 10.1093/mnrasl/slad095

M. Kovalev, O. Hainaut, Xuefei Chen, Zhanwen Han

引用次数: 0

Neutrino-driven massive stellar explosions in 3D fostered by magnetic fields via turbulent α-effect 磁场通过湍流α效应促进中微子驱动的三维大质量恒星爆炸

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-07 DOI: 10.1093/mnrasl/slad173

J. Matsumoto, T. Takiwaki, K. Kotake

引用次数: 0

Cataclysmic variables are a key population of gravitational wave sources for LISA 突变变量是LISA引力波源的关键种群

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-05 DOI: 10.1093/mnrasl/slad093

S. Scaringi, K. Breivik, T. Littenberg, C. Knigge, P. Groot, M. Veresvarska

{"title":"Cataclysmic variables are a key population of gravitational wave sources for LISA","authors":"S. Scaringi, K. Breivik, T. Littenberg, C. Knigge, P. Groot, M. Veresvarska","doi":"10.1093/mnrasl/slad093","DOIUrl":"https://doi.org/10.1093/mnrasl/slad093","url":null,"abstract":"\u0000 The gravitational wave (GW) signals from the Galactic population of cataclysmic variables (CVs) have yet to be carefully assessed. Here we estimate these signals and evaluate their significance for LISA. First, we find that at least three known systems are expected to produce strong enough signals to be individually resolved within the first four years of LISA’s operation. Second, CVs will contribute significantly to the LISA Galactic binary background, limiting the mission’s sensitivity in the relevant frequency band. Third, we predict a spike in the unresolved GW background at a frequency corresponding to the CV minimum orbital period. This excess noise may impact the detection of other systems near this characteristic frequency. Fourth, we note that the excess noise spike amplitude and location associated with Pmin ∼ 80 min can be used to measure the CV space density and period bounce location with complementary and simple GW biases compared to the biases and selection effects plaguing samples selected from electromagnetic signals. Our results highlight the need to explicitly include the Galactic CV population in the LISA mission planning, both as individual GW sources and generators of background noise, as well as the exciting prospect of characterising the CV population through their GW emission.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"329 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81045763","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

Correction to: Modelling annual scintillation velocity variations of FRB 20201124A 修正:模拟FRB 20201124A的年闪烁速度变化

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-07-04 DOI: 10.1093/mnrasl/slad090

R. Main, S. Bethapudi, V. R. Marthi, M. L. Bause, D. Z. Li, H.-H. Lin, L. Spitler, R. Wharton

引用次数: 0

Machine learning identified molecular fragments responsible for infrared emission features of polycyclic aromatic hydrocarbons 机器学习识别了多环芳烃红外发射特征的分子片段

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-06-30 DOI: 10.1093/mnrasl/slad089

Zhisen Meng, Yong Zhang, E. Liang, Zhao Wang

引用次数: 0

Eccentric debris disc morphologies II: Surface brightness variations from overlapping orbits in narrow eccentric discs 偏心碎片盘形态II:狭窄偏心盘中重叠轨道的表面亮度变化

Monthly Notices of the Royal Astronomical Society: Letters Pub Date : 2023-06-23 DOI: 10.1093/mnrasl/slad083

J. Lovell, Elliot M. Lynch

{"title":"Eccentric debris disc morphologies II: Surface brightness variations from overlapping orbits in narrow eccentric discs","authors":"J. Lovell, Elliot M. Lynch","doi":"10.1093/mnrasl/slad083","DOIUrl":"https://doi.org/10.1093/mnrasl/slad083","url":null,"abstract":"\u0000 We present Paper II of the Eccentric Debris Disc Morphologies series to explore the effects that significant free and forced eccentricities have on high-resolution millimetre-wavelength observations of debris discs, motivated by recent ALMA images of HD53143’s disc. In this work, we explore the effects of free eccentricity, and by varying disc fractional widths and observational resolutions, show for a range of narrow eccentric discs, orbital overlaps result in dust emission distributions that have either one or two radial peaks at apocentre and/or pericentre. The narrowest discs contain two radial peaks, whereas the broadest discs contain just one radial peak. For fixed eccentricities, as fractional disc widths are increased, we show that these peaks merge first at apocentre (producing apocentre glow), and then at pericentre (producing pericentre glow). Our work thus demonstrates that apocentre/pericentre glows in models with constant free and forced eccentricities can be both width and resolution dependent at millimetre wavelengths, challenging the classical assertion that apocentre/pericentre glows are purely wavelength dependent. We discuss future high-resolution observations that can distinguish between competing interpretations of underlying debris disc eccentricity distributions.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74102095","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