Serbian Astronomical Journal最新文献_第4页

Impossible moons - transit timing effects that cannot be due to exomoon 不可能的卫星-凌日时间效应，不可能是由于外月球

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-04-08 DOI: 10.2298/saj2001025k

D. Kipping, A. Teachey

{"title":"Impossible moons - transit timing effects that cannot be due to exomoon","authors":"D. Kipping, A. Teachey","doi":"10.2298/saj2001025k","DOIUrl":"https://doi.org/10.2298/saj2001025k","url":null,"abstract":"Exomoons are predicted to produce transit timing variations (TTVs) upon\u0000 their host planet. Unfortunately, so are many other astrophysical phenomena\u0000 - most notably other planets in the system. In this work, an argument of\u0000 reductio ad absurdum is invoked, by deriving the transit timing effects that\u0000 are impossible for a single exomoon to produce. Our work derives three key\u0000 analytic tests. First, one may exploit the fact that a TTV signal from an\u0000 exomoon should be accompanied by transit duration variations (TDVs), and\u0000 that one can derive a TDV floor as a minimum expected level of variability.\u0000 Cases for which the TDV upper limit is below this floor can thus be killed as\u0000 exomoon candidates. Second, formulae are provided for estimating whether\u0000 moons are expected to be \"killable\" when no TDVs presently exist, thus\u0000 enabling the community to estimate the value of deriving TDVs beforehand.\u0000 Third, a TTV ceiling is derived, above which exomoons should never be able\u0000 to produce TTV amplitudes. These tools are applied to a catalog of TTVs and\u0000 TDVs for two and half thousand Kepler Objects of Interest, revealing over\u0000 two hundred cases that cannot be due to a moon - remarkably then a large\u0000 fraction of the known TTV amplitudes are consistent with being caused by a\u0000 moon. These tests are also applied to the exomoon candidate Kepler-1625b i,\u0000 which comfortably passes the criteria. These simple analytic results should\u0000 provide a means of rapidly rejecting putative exomoons and streamlining the\u0000 search for satellites.","PeriodicalId":48878,"journal":{"name":"Serbian Astronomical Journal","volume":"1 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2020-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44044774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 4

Global parameters of the newly-discovered W UMa stars WISEJ004327.7+722407 and WISEJ234557.8+510456 新发现的wuma恒星WISEJ004327.7+722407和WISEJ234557.8+510456的全局参数

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-01-01 DOI: 10.2298/saj2000019k

D. Kjurkchieva, S. Ibryamov

引用次数: 0

Life, educational and scientific activities of professor Mirjana Vukicevic-Karabin (1933-2020) Mirjana Vukicevic-Karabin教授的生活、教育和科学活动(1933-2020)

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-01-01 DOI: 10.2298/saj2001049v

I. Vince, O. Atanacković

引用次数: 0

Cosmic time for multi-component universe 多组分宇宙的宇宙时间

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-01-01 DOI: 10.2298/saj2001015b

D. Branković

引用次数: 1

The evolution of massive binary systems 大质量双星系统的演化

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-01-01 DOI: 10.2298/saj2001001p

J. Petrovic

引用次数: 0

Classification of asteroid families with artificial neural networks 用人工神经网络对小行星族进行分类

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-01-01 DOI: 10.2298/saj2001039v

D. Vujičić, R. Pavlović, D. Milosevic, B. Djordjevic, S. Randjić, Dijana Stojić

引用次数: 3

The relationship between the `limiting' Yarkovsky drift speed and asteroid families' Yarkovsky V-shape “极限”亚尔科夫斯基漂移速度与小行星家族亚尔科夫斯基v型的关系

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2020-01-01 DOI: 10.2298/saj2000025m

I. Milic-Zitnik

{"title":"The relationship between the `limiting' Yarkovsky drift speed and asteroid families' Yarkovsky V-shape","authors":"I. Milic-Zitnik","doi":"10.2298/saj2000025m","DOIUrl":"https://doi.org/10.2298/saj2000025m","url":null,"abstract":"The Yarkovsky effect is an important force to consider in order to understand the long-term dynamics of asteroids. This non-gravitational force affects the orbital elements of objects revolving around a source of heat, especially their semi-major axes. Following the recently defined `limiting' value of the Yarkovsky drift speed at 7x10-5 au/Myr in Milic Zitnik (2019) (below this value of speed asteroids typically jump quickly across the mean motion resonances), we decided to investigate the relation between the asteroid family Yarkovsky V-shape and the `limiting' Yarkovsky drift speed of asteroid's semi-major axes. We have used the known scaling formula to calculate the Yarkovsky drift speed (Spoto et al. 2015) in order to determine the inner and outer `limiting' diameters (for the inner and outer V-shape borders) from the `limiting' Yarkovsky drift speed. The method was applied to 11 asteroid families of different taxonomic classes, origin type and age, located throughout the Main Belt. Here, we present the results of our calculation on relationship between asteroid families' V-shapes (crossed by strong and/or weak mean motion resonances) and the `limiting' diameters in the (a, 1=D) plane. Our main conclusion is that the `breakpoints' in changing V-shape of the very old asteroid families, crossed by relatively strong mean motion resonances on both sides very close to the parent body, are exactly the inverse of `limiting' diameters in the a versus 1=D plane. This result uncovers a novel interesting property of asteroid families' Yarkovsky V-shapes.","PeriodicalId":48878,"journal":{"name":"Serbian Astronomical Journal","volume":"56 1","pages":"25-41"},"PeriodicalIF":0.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68674356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

Photometric and spectroscopic study of five pre-main sequence stars in the vicinity of NGC 7129 NGC 7129附近五颗主序星的光度和光谱研究

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2019-11-15 DOI: 10.2298/SAJ1999039S

E. Semkov, S. Ibryamov, S. Peneva

{"title":"Photometric and spectroscopic study of five pre-main sequence stars in the vicinity of NGC 7129","authors":"E. Semkov, S. Ibryamov, S. Peneva","doi":"10.2298/SAJ1999039S","DOIUrl":"https://doi.org/10.2298/SAJ1999039S","url":null,"abstract":"We present results from long-term optical photometric and spectroscopic\u0000 observations of five pre-main sequence stars, located in the vicinity of the\u0000 bright nebula NGC 7129. We obtained UBVRI photometric observations in the\u0000 field centered on the star V391 Cep, north-west of the bright nebula NGC\u0000 7129. Our multicolor CCD observations spanned the period from February 1998\u0000 to November 2016. At the time of our photometric monitoring, a total of\u0000 thirteen medium-resolution optical spectra of the stars were obtained. The\u0000 results from our photometric study show that all stars exhibit strong\u0000 variability in all optical passbands. Long-term light curves of the five\u0000 stars indicate the typical classical T Tauri star variations in brightness\u0000 with large amplitudes. We did not find any reliable periodicity in the\u0000 brightness variations of all five stars. The results from spectral\u0000 observations showed that all studied stars can be classified as classical T\u0000 Tauri stars with rich emission line spectra and strong variability in\u0000 profiles and intensity of emission lines.","PeriodicalId":48878,"journal":{"name":"Serbian Astronomical Journal","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49345971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 1

Habitability of galaxies and the application of merger trees in astrobiology 星系的宜居性及合并树在天体生物学中的应用

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2019-06-01 DOI: 10.2298/SAJ1998025S

N. Stojković, B. Vukotić, M. Ćirković

{"title":"Habitability of galaxies and the application of merger trees in astrobiology","authors":"N. Stojković, B. Vukotić, M. Ćirković","doi":"10.2298/SAJ1998025S","DOIUrl":"https://doi.org/10.2298/SAJ1998025S","url":null,"abstract":"Galaxies represent the main form of organization of matter in our universe.\u0000 Therefore, they are of obvious interest for the new multidisciplinary field\u0000 of astrobiology. In particular, to study habitability of galaxies represents\u0000 one of the main emerging challenges of theoretical and numerical\u0000 astrobiology. Its theoretical underpinnings are, however, often confused and\u0000 vague. Here we present a systematic attempt to list and categorize major\u0000 causal factors playing a role in emergent habitability of galaxies.\u0000 Furthermore, we argue that the methodology of cosmological merger trees is\u0000 particularly useful in delineating what are systematic and lawful\u0000 astrobiological properties of galaxies at present epoch vs. those which are\u0000 product of historical contingency and, in particular, interaction with wider\u0000 extragalactic environment. Employing merger trees extracted from\u0000 cosmological N-body simulations as a new and promising research method for\u0000 astrobiology has been pioneered by Stanway et al. (2018). We analyse the\u0000 general issue of applicability of merger trees and present preliminary\u0000 results on a set of trees extracted from the Illustris Project. In a sense,\u0000 this approach is directly complementary to using large-scale cosmological\u0000 simulations to study habitable zones of individual galaxies with high\u0000 mass/spatial resolution; taken together, they usher a new era of synergy and\u0000 synthesis between cosmology and astrobiology.","PeriodicalId":48878,"journal":{"name":"Serbian Astronomical Journal","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48818089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

引用次数: 0

The stellar atmosphere physical system II. An operative sequential algorithm to solve the stellar atmosphere problem 恒星大气物理系统II。一种求解恒星大气问题的可操作序列算法

IF 0.5 4区物理与天体物理

Serbian Astronomical Journal Pub Date : 2019-06-01 DOI: 10.2298/SAJ190215001C

L. Crivellari

引用次数: 2