The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be seen and understood with precise data. This work is triggered by the most recent data release of the astrometric space mission Gaia and uses its unprecedented high precision parallax measurements to review the census of objects within 10 pc. The first aim of this work was to compile all stars and brown dwarfs within 10 pc observable by Gaia, and compare it with the Gaia Catalogue of Nearby Stars as a quality assurance test. We complement the list to get a full 10 pc census, including bright stars, brown dwarfs, and exoplanets. We started our compilation from a query on all objects with a parallax larger than 100 mas using SIMBAD. We completed the census by adding companions, brown dwarfs with recent parallax measurements not in SIMBAD yet, and vetted exoplanets. The compilation combines astrometry and photometry from the recent Gaia Early Data Release 3 with literature magnitudes, spectral types and line-of-sight velocities. We give a description of the astrophysical content of the 10 pc sample. We find a multiplicity frequency of around 28%. Among the stars and brown dwarfs, we estimate that around 61% are M stars and more than half of the M stars are within the range M3.0 V to M5.0 V. We give an overview of the brown dwarfs and exoplanets that should be detected in the next Gaia data releases along with future developments. We provide a catalogue of 540 stars, brown dwarfs, and exoplanets in 339 systems, within 10 pc from the Sun. This list is as volume-complete as possible from current knowledge and provides benchmark stars that can be used, for instance, to define calibration samples and to test the quality of the forthcoming Gaia releases. It also has a strong outreach potential.
The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be studied and understood with precise data. This work is an update of the 10 pc sample published by Reylé et al. (2021) that used the unprecedented high precision parallax measurements from the early third data release of the astrometric space mission Gaia. We review this census, all updates being related to close binaries, brown dwarfs and exoplanets. We provide a new catalogue of 541 stars, brown dwarfs, and exoplanets in 336…
Close encounters of stars to the Sun could affect life on Earth through gravitational perturbations of comets in the Oort cloud or exposure to ionizing radiation. By integrating orbits through the Galactic potential, I identify which of 33 million stars in Gaia DR3 with complete phase space information come close to the Sun. 61 stars formally approach within 1 pc, although there is high confidence in only 42 (two thirds) of these, the rest being spurious measurements or (in) binary systems. Most of the stars will encounter within the past or future 6 Myr; earlier/later encounters are less comm…
Recent analyses of the Gaia data have identified diffuse stellar populations surrounding nearby open clusters. It is important to verify that these "halos", "tails", and "strings" are of similar ages and compositions as stars in the denser part of the cluster. We present an analysis of NGC 2516 ($\approx$150 Myr), which has a classical tidal radius of 10 pc and an apparent halo of stars spanning 500 pc ($20^\circ$ on-sky). Combining photometry from Gaia, rotation periods from TESS, and lithium measurements from Gaia-ESO and GALAH, we find that the halo of NGC 2516 is the same age as the cluste…
We present estimates of distances, ages and masses for over 6 million stars. These estimates are derived from the combination of spectrophotometric data and Gaia eDR3 parallaxes. For that, we used the previously published Unified tool to estimate Distances, Ages, and Masses (UniDAM).
New axion bounds derived from the 100-parsec Gaia DR3 white dwarf luminosity function
Instituto de Astrofísica de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas（拉普拉塔天体物理研究所，阿根廷国家科学研究委员会）；Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata（拉普拉塔国立大学天文与地球物理学院）；Departament de Física, Universitat Politècnica de Catalunya（加泰罗尼亚理工大学物理系）；Department of Theoretical Physics, CERN（欧洲核子研究组织理论物理部）；Dipartimento di Fisica, “Sapienza” Università di Roma & Sezione INFN Roma1（罗马第一大学物理系及意大利国家核物理研究所罗马一分部）；Department of Particle Physics and Astrophysics, Weizmann Institute of Science（魏茨曼科学研究所粒子物理与天体物理学系）
Classical Cepheids in open clusters are key ingredients for stellar population studies and the characterization of variable stars, as they are tracers of young and massive populations and of recent star formation episodes. Cluster Cepheids are of particular importance since they can be age dated by using the cluster's stellar population to obtain the Cepheid period-luminosity-age relation. In this contribution, we present the preliminary results of an all-sky search for classical Cepheids in Galactic open clusters by taking advantage of the unprecedented astrometric precision of the second dat…
We present MINESweeper, a tool to measure stellar parameters by jointly fitting observed spectra and broadband photometry to model isochrones and spectral libraries. This approach enables the measurement of spectrophotometric distances, in addition to stellar parameters such as Teff, log(g), [Fe/H], [a/Fe], and radial velocity. MINESweeper employs a Bayesian framework and can easily incorporate a variety of priors, including Gaia parallaxes. Mock data are fit in order to demonstrate how the precision of derived parameters depends on evolutionary phase and SNR. We then fit a selection of data i…
The advent of Gaia has led to the discovery of nearly 300 elongated stellar associations (called `strings') spanning hundreds of parsecs in length and mere tens of parsecs in width. These newfound populations present an excellent laboratory for studying the assembly process of the Milky Way thin disk. In this work, we use data from GALAH DR3 to investigate the chemical distributions and ages of 18 newfound stellar populations, 10 of which are strings and 8 of which are compact in morphology. We estimate the intrinsic abundance dispersions in [X/H] of each population and compare them with those…
With the help of Gaia data, it is noted that in addition to the core components, there are low-density outer halo components in the extended region of open clusters. To study the extended structure beyond the core radius of the cluster ($\sim$ 10 pc), based on Gaia EDR3 data, taking up to 50 pc as the searching radius, we use the pyUPMASK algorithm to re-determine the member stars of the open cluster within 1-2 kpc. We obtain the member stars of 256 open clusters, especially those located in the outer halo region of open clusters. Furthermore, we find that most open clusters' radial density pr…
The period versus mass diagrams (i.e., rotational sequences) of open clusters provide crucial constraints for angular momentum evolution studies. However, their memberships are often heavily contaminated by field stars, which could potentially bias the interpretations. In this paper, we use data from Gaia DR2 to re-assess the memberships of seven open clusters with ground- and space-based rotational data, and present an updated view of stellar rotation as a function of mass and age. We use the Gaia astrometry to identify the cluster members in phase-space, and the photometry to derive revised …
A pioneering study showed that the fine structure in the luminosity function (LF) of young star clusters contains information about the evolutionary stage (age) and composition of the stellar population. The notable features include the H-peak, which is the result of the onset of hydrogen burning turning pre-main sequence stars into main sequence stars. The feature moves toward the faint end of the LF, and eventually disappears as the population evolves. Another detectable feature is the Wielen dip, a dip at M_V ~ 7 mag in the LF first identified in 1974 for stars in the solar environment. Lat…
The spatial distribution, Galactic model parameters and luminosity function of cataclysmic variables (CVs) are established using re-estimated trigonometric parallaxes of {\it Gaia} DR3. The data sample of 1,587 CVs in this study is claimed to be suitable for Galactic model parameter estimation as the distances are based on trigonometric parallaxes and the {\it Gaia} DR3 photometric completeness limits were taken into account when the sample was created. According to the analysis, the scale height of All CVs increases from 248$\pm$2 to 430$\pm$4 pc towards shorter periods near the lower limit o…
Photometric metallicity of Galactic RR Lyrae stars in the Gaia DR3 era
University of Delhi（德里大学）；Indian Institute of Astrophysics（印度天体物理研究所）；Inter-University Center for Astronomy and Astrophysics（大学间天文与天体物理中心）；University of Petroleum and Energy Studies（石油与能源大学）
We search through an eight-million cubic-parsec volume surrounding the Pleiades star cluster and the Sun to identify both the current and past members of the Pleiades cluster within the Gaia EDR3 dataset. We find nearly 1,300 current cluster members and 289 former cluster candidates. Many of these candidates lie well in front or behind the cluster from our point of view, so formerly they were considered cluster members, but their parallaxes put them more than 10 pc from the centre of the cluster today. Over the past 100 Myr we estimate that the cluster has lost twenty percent of its mass inclu…
Methods of obtaining stellar luminosities (L) have been revised and a new concept, standard stellar luminosity, has been defined. Among the three methods (direct method from radii and effective temperatures, method using a mass-luminosity relation (MLR), and method requiring a bolometric correction), the third method, which uses the unique bolometric correction (BC) of a star extracted from a flux ratio ($f_{\rm V}/f_{\rm Bol}$) obtained from the observed spectrum with sufficient spectral coverage and resolution, is estimated to provide an uncertainty ($ΔL/L$) typically at a low percentage, wh…
Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity $0.008\leq Z\leq 0.040$. Stellar parameters, light ratios, Gaia DR2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected eligible to calculate empirical bolometric corrections. NASA-IPAC Galactic dust maps were main source of extinctions. Unreliable extinctions at low Galactic latitudes $|b|\leq5^o$ were replaced with individual determinations, if they exist in the li…
[...] This paper presents a rigorous derivation of a goodness-of-fit statistics for colour-magnitude diagrams (CMD). We discuss the reliability of the underlying assumptions and their validity. We derived the distribution of the sum of squared Mahalanobis distances of stellar data and theoretical isochrone for a generic set of data and models. We applied this to the case of synthetic CMDs constructed to mimic real data of open clusters in the GAIA sample. We analysed the capability of distinguishing among different sets of input physics and parameters that were used to compute the stellar mode…
Hypervelocity Stars in the Gaia era. Revisiting the most extreme stars from the MMT survey
在多镜望远镜（MMT）上进行的超高速星（HVS）巡天发现了42颗在银河系静止坐标系中径向速度超过$+275\,$ km $\,$ s ${}^{-1}$的银河系晕中的B型星。为了解开这些高速异常值的性质和起源，需要它们完整的六维相空间信息。为此，我们补充了位置和自行从第二次数据发布的{ \it盖亚}与修订的径向速度和分光光度计的距离，是基于重新分析的可用MMT光谱的40个对象，使用国家的最先进的模型光谱和定制的分析策略。由此产生的37颗恒星的位置和速度矢量，然后作为输入，为随后的运动学调查，以获得尽可能完整的图片。综合预测的自转速度、在基尔图中的位置和运动学性质，样本中除了两颗（B576、B598）外的所有天体都很可能是主序星。虽然现有的数据仍然不够精确，无法限制19颗程序星的起源地，但我们确定了8个来自银河系盘外缘或根本不是来自银河系盘的物体，以及10个可能来自银河系盘的物体。对于几乎所有这18个或多或少具有良好约束空间起源的目标，银河系中心（GC）作为可能的起源地是不合格的。最值得注意的例外是B576，当假设它具有蓝色水平分支（BHB）性质时，它的起源与GC非常吻合。HVS $\,$ 22是迄今为止样品中最极端的物体。虽然它的起源是完全不受约束的，但希尔斯机制从GC中喷出是其当前银河系静止系速度为$1530^{+690}_{-560}\,$ km $\,$ s ${}^{-1}…
We describe a homogeneous catalog compilation of common proper motion stars based on Gaia DR2. A preliminary list of all pairs of stars within the radius of 100 pc around the Sun with a separation less than a parsec was compiled. Also, a subset of comoving pairs, wide binary stars, was selected. The clusters and systems with multiplicity larger than 2 were excluded from consideration. The resulting catalog contains 10358 pairs of stars. The catalog selectivity function was estimated by comparison with a set of randomly selected field stars and with a model sample obtained by population synthes…
