اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدCAFE-BEANS: An exhaustive hunt for high-mass binaries
55
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
CAFE-BEANS is an on-going survey running on the 2.2 m telescope at Calar Alto. For more than two years, CAFE-BEANS has been collecting high-resolution spectra of early-type stars with the aim of detecting and characterising spectroscopic binaries. The main goal of this project is a thorough characterisation of multiplicity in high-mass stars by detecting all spectroscopic and visual binaries in a large sample of Galactic O-type stars, and solving their orbits. Our final objective is eliminating all biases in the high-mass-star IMF created by undetected binaries.
قيم البحث
اقرأ أيضاً
We report the very first analysis of 27 eclipsing binary systems with high eccentricities that sometimes reach up to 0.8. The orbital periods for these systems range from 1.4 to 37 days, and the median of the sample is 10.3 days. Star CzeV3392 (= UCA
C4 623 022784), for example, currently is the eclipsing system with the highest eccentricity (e = 0.22) of stars with a period shorter than 1.5 days. We analysed the light curves of all 27 systems and obtained the physical parameters of both components, such as relative radii, inclinations, or relative luminosities. The most important parameters appear to be the derived periods and eccentricities. They allow constructing the period-eccentricity diagram. This eccentricity distribution is used to study the tidal circularisation theories. Many systems have detected third-light contributions, which means that the Kozai-Lidov cycles might also be responsible for the high eccentricities in some of the binaries.
The origin of massive stars is a fundamental open issue in modern astrophysics. Pre-ALMA interferometric studies reveal precursors to early B to late O type stars with collapsing envelopes of 15-20 M$_odot$ on 1000-3000 AU size-scales. To search for
more massive envelopes we selected the most massive nearby young clumps from the ATLASGAL survey to study their protostellar content with ALMA. Our first results using the intermediate scales revealed by the ALMA ACA array providing 3-5 angular resolution, corresponding to $sim$0.05-0.1 pc size-scales, reveals a sample of compact objects. These massive dense cores are on average two-times more massive than previous studies of similar types of objects. We expect that once the full survey is completed, it will provide a comprehensive view on the origin of the most massive stars.
Many high-mass X-ray binaries (HMXBs) are runaways. Stellar wind and radiation of donor stars in HMXBs along with outflows and jets from accretors interact with the local interstellar medium and produce curious circumstellar structures. Several such
structures are presented and discussed in this contribution.
We perform a search for binary black hole mergers with one subsolar mass black hole and a primary component above $2 M_odot$ in the second observing run of LIGO/Virgo. Our analysis therefore extends previous searches into a mass region motivated by t
he presence of a peak in any broad mass distribution of primordial black holes (PBHs) around $[2-3] M_odot$ coming from the equation of state reduction at the QCD transition. Four candidate events are found passing a false alarm rate (FAR) threshold of 2 per year, although none are statistically significant enough for being clear detections. We first derive model independent limits on the PBH merging rates assuming a null result of the search. Then we confront them to two recent scenarios in which PBHs can constitute up to the totality of the Dark Matter, explain LIGO/Virgo mergers and the possible observation of a stochastic gravitational-wave background by NANOGrav. We find that these models still pass the rate limits and conclude that the analysis of the O3 and O4 observing runs will be decisive to test the hypothesis of a primordial origin of black hole mergers.
Context. Intermediate- to high-mass stars are the least numerous types of stars and they are less well understood than their more numerous low-mass counterparts in terms of their internal physical processes. Modelling the photometric variability of a
large sample of main-sequence intermediate- to high-mass stars in eclipsing binary systems will help to improve the models for such stars. Aims. Our goal is to compose a homogeneously compiled sample of main-sequence intermediate- to high-mass OBA-type dwarfs in eclipsing binary systems from TESS photometry. We search for binaries with and without pulsations and determine their approximate ephemerides. Methods. Our selection starts from a catalogue of dwarfs with colours corresponding to those of OBA-type dwarfs in the TESS Input Catalog. We develop a new automated method aimed at detecting eclipsing binaries in the presence of strong pulsational and/or rotational signal relative to the eclipse depths and apply it to publicly available 30-min cadence TESS light curves. Results. Using targets with TESS magnitudes below 15 and cuts in the 2MASS magnitude bands of $J - H < 0.045$ and $J - K < 0.06$ as most stringent criteria, we arrive at a total of 189 981 intermediate- to high-mass candidates, 91193 of which have light curves from at least one of two data reduction pipelines. The eclipsing binary detection and subsequent manual check for false positives resulted in 3155 unique OBA-type eclipsing binary candidates. Conclusions. Our sample of eclipsing binary stars in the intermediate- to high-mass regime allows for future binary (and asteroseismic) modelling with the aim to better understand the internal physical processes in this hot part of the main sequence.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
