A SOPHIE RV search for planets around young nearby stars (YNS). A combination with the HARPS YNS survey

The absolute magnitudes of δ Scuti stars derived from parallaxes measured by the Hipparcos satellite were compared with the previous estimates based on photometric uvby² indices, and significant differences were found which are related to photometric effects of metallicity and rotational velocity. A reliable calibration of Mv in terms of the photometric indices shall include an estimate of these effects. It is important also to take into account the possible presence of unresolved close companions in order to fully exploit the accuracy of Mv of nearby stars derived from the trigonometric parallaxes. The Mv of few bright SX Phe stars support the period-luminosity relation obtained with ground based observations of globular clusters, while it does not seem to confirm the empirical dependence of this relation on the metallicity. Some high amplitude δ Scuti stars with intermediate or normal metallicity and small and uncertain parallax have apparently a very low luminosity. Simulations of Mv determinations from observed parallaxes based on the discussion of observational errors by Lutz and Kelker (1973) have shown that the low luminosity could be an effect related to these errors.

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Bayesian constraints on the origin and geology of exo-planetary material using a population of externally polluted white dwarfs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab736 ◽

2021 ◽

Author(s):

John H D Harrison ◽

Amy Bonsor ◽

Mihkel Kama ◽

Andrew M Buchan ◽

Simon Blouin ◽

...

Keyword(s):

Solar System ◽

White Dwarf ◽

Bayesian Model ◽

Total Mass ◽

White Dwarfs ◽

Bulk Composition ◽

Planetary Systems ◽

The Moon ◽

Planetary Bodies ◽

Nearby Stars

Abstract White dwarfs that have accreted planetary bodies are a powerful probe of the bulk composition of exoplanetary material. In this paper, we present a Bayesian model to explain the abundances observed in the atmospheres of 202 DZ white dwarfs by considering the heating, geochemical differentiation, and collisional processes experienced by the planetary bodies accreted, as well as gravitational sinking. The majority (>60%) of systems are consistent with the accretion of primitive material. We attribute the small spread in refractory abundances observed to a similar spread in the initial planet-forming material, as seen in the compositions of nearby stars. A range in Na abundances in the pollutant material is attributed to a range in formation temperatures from below 1,000 K to higher than 1,400 K, suggesting that pollutant material arrives in white dwarf atmospheres from a variety of radial locations. We also find that Solar System-like differentiation is common place in exo-planetary systems. Extreme siderophile (Fe, Ni or Cr) abundances in 8 systems require the accretion of a core-rich fragment of a larger differentiated body to at least a 3σ significance, whilst one system shows evidence that it accreted a crust-rich fragment. In systems where the abundances suggest that accretion has finished (13/202), the total mass accreted can be calculated. The 13 systems are estimated to have accreted masses ranging from the mass of the Moon to half that of Vesta. Our analysis suggests that accretion continues for 11Myrs on average.

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The Mass-Luminosity Relation From Binaries

Highlights of Astronomy ◽

10.1017/s1539299600021602 ◽

1998 ◽

Vol 11 (1) ◽

pp. 419-420

Author(s):

David W. Latham

Keyword(s):

Eclipsing Binaries ◽

M Dwarfs ◽

Direct Measurements ◽

Nearby Stars ◽

The Masses ◽

Stellar Masses ◽

M Dwarf ◽

Magnitude Difference ◽

Astrometric Binaries ◽

Better Than

What is known about the masses of main-sequence stars from the analysis of binary orbits? Double-lined eclipsing binaries are the main source of very precise stellar masses and radii (e.g. Andersen 1997), contributing more than 100 determinations with better than 2% precision over the range 0.6 to 20 Mʘ. For lower-mass stars we are forced to turn to nearby systems with astrometric orbits (e.g. Henry et al. 1993). Not only is the number of good mass determinations from such systems smaller, but also the precision is generally poorer. We are approaching an era when interferometers should have a major impact by supplying good astrometric orbits for dozens of double-lined systems. Already we are beginning to see the sorts of results to expect from this (e.g. Torres et al. 1997). Figure 1. Mass vs. absolute V magnitude for eclipsing binaries (circles) and nearby astrometric binaries (squares) Figure 1 is an updated version of a diagram presented by Henry et al. (1993, their Figure 2). It shows the general run of mass determinations from about 10 Mʘ down to the substellar limit near 0.075 Mʘ. Ninety of the points in Figure 1 are for eclipsing binary masses from Andersen’s review (1991) and are plotted as open circles. The results for eclipsing binaries published since 1991 are plotted as 30 filled circles, adopting the same limit of 2% for the mass precision. In most cases the uncertainties are similar to the size of the symbols. Especially noteworthy is the pair of new points for CM Draconis (Metcalfe et al. 1996) with masses near 0.25 Mʘ. Together with the points for YY Geminorum near 0.6 Mʘ, these are the only M dwarfs that have precise mass determinations. For the most part we are forced to rely on nearby stars with astrometric orbits, to fill in the M dwarf region of the diagram. We have used filled squares in Figure 1 for 29 such systems from Henry et al. (1993), updated using 14 new parallaxes from Hipparcos and 4 from the new Yale Parallax Catalog (1995). Gliese 508 is not included, because it is now known to be a triple, while Gliese 67AB, 570BC, and 623AB are not included because there are not yet any direct measurements of the V magnitude difference for these systems.

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The Age of Old Galactic Populations

Highlights of Astronomy ◽

10.1017/s1539299600022152 ◽

1998 ◽

Vol 11 (1) ◽

pp. 560-561

Author(s):

M. Grenon

Keyword(s):

High Velocity ◽

Radial Velocities ◽

Thick Disk ◽

Early Evolution ◽

Galactic Bulge ◽

Colour Class ◽

The Galaxy ◽

Nearby Stars

As a preparation to the HIPPARCOS mission, a large observing programme on NLTT stars (propermotion > 0.18 ″/yr) was started in Genevaphotometry. The original programme consists of 10047 stars brighter than mR = 11.5, or mR = 12.5 if of colour class m. Among them, 7813 targets could be included in the HIPPARCOS programme, selected according to their observability and internal priorities in favour of large parallaxe stars (photometric distances < 100 pc) and high-velocity stars. The bulk of new nearby, halo, mild-metal poor and SMR stars in the HIP Catalogue originates from this proposal (N° 139). No less than 208 new nearby stars with π ≥ 40 mas were discovered south of δ +10°, the closest has π(HIP)= 182 mas. Radial velocities were obtained with CORAVEL at OHP and ESO. Most aspects of the early evolution of the Galaxy may be addressed with this sample. Here we discuss, as examples, the ages of the thick disk and of the galactic bulge.

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Giant planets around AF and M stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313007898 ◽

2013 ◽

Vol 8 (S299) ◽

pp. 64-65

Author(s):

Julien Rameau ◽

Gaël Chauvin ◽

Anne-Marie Lagrange ◽

Philippe Delorme ◽

Justine Lannier

Keyword(s):

Giant Planets ◽

Early Type ◽

Late Type ◽

M Dwarfs ◽

Low Mass Stars ◽

Planetary Mass ◽

Nearby Stars ◽

Low Mass ◽

M Stars ◽

The One

AbstractWe present the results of two three-year surveys of young and nearby stars to search for wide orbit giant planets. On the one hand, we focus on early-type and massive, namely β Pictoris analogs. On the other hand, we observe late type and very low mass stars, i.e., M dwarfs. We report individual detections of new planetary mass objects. According to our deep detection performances, we derive the observed frequency of giant planets between these two classes of parent stars. We find frequency between 6 to 12% but we are not able to assess a/no correlation with the host-mass.

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Submillimetre images of dusty debris around nearby stars

Nature ◽

10.1038/33874 ◽

1998 ◽

Vol 392 (6678) ◽

pp. 788-791 ◽

Cited By ~ 317

Author(s):

Wayne S. Holland ◽

Jane S. Greaves ◽

B. Zuckerman ◽

R. A. Webb ◽

Chris McCarthy ◽

...

Keyword(s):

Nearby Stars

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Homogeneous photospheric parameters and C abundances in G and K nearby stars with and without planets

Astronomy and Astrophysics ◽

10.1051/0004-6361/201015907 ◽

2010 ◽

Vol 526 ◽

pp. A71 ◽

Cited By ~ 29

Author(s):

R. Da Silva ◽

A. C. Milone ◽

B. E. Reddy

Keyword(s):

Nearby Stars

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THE ZADKO OBSERVATORY

Revista Mexicana de Astronomía y Astrofísica Serie de Conferencias ◽

10.22201/ia.14052059p.2021.53.08 ◽

2021 ◽

Vol 53 ◽

pp. 35-39

Author(s):

J. A. Moore ◽

B. Gendre ◽

D. M. Coward ◽

H. Crisp ◽

A. Klotz

Keyword(s):

Media Coverage ◽

Gamma Ray ◽

European Space Agency ◽

Global Awareness ◽

The Public ◽

Technical Management ◽

Space Agency ◽

Nearby Stars ◽

Near Earth Asteroids ◽

Single Instrument

The 1.0 metre f/4 fast-slew Zadko Telescope was installed in June 2008 approximately seventy kilometres north of Perth at Yeal, in the Shire of Gingin, Western Australia. Since the Zadko Telescope has been in operation it has proven its worth by detecting numerous Gamma Ray Burst afterglows, two of these being the most distant 'optical transients' imaged by an Australian telescope. Other projects include a contract with the European Space Agency (ESA) to image potentially hazardous near Earth asteroids (2019), monitoring space weather on nearby stars (2019), and photometry of a transit of Saturn's moon Titan (2018). Another active Zadko Telescope project is tracking Geostationary satellites and attempting to use photometry to classify various space debris (defunct satellites). The Zadko Telescope's importance as a potential tool for education, training, and public outreach cannot be underestimated, as the global awareness of the importance of astronomy (and space science) as a context for teaching science continues to increase. An example of this was the national media coverage of its contribution to the discovery of colliding neutron stars in 2017, capturing the imagination of the public. In this proceeding, I will focus on the practical aspects of managing a robotic Observatory, focusing on the sustainability of the Observatory and the technical management involved in hosting different commercial projects. I will review the evolution of the Observatory, from its early, single instrument, state to its current multi-telescope and multi-instrument capabilities. I will finish by outlining the future of the Observatory and the site.

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New Distant Companions to Known Nearby Stars. I. GJ 4047B, GJ 718B, GJ 747.2C, GJ 4100B, and GJ 4153B

The Astronomical Journal ◽

10.1086/340703 ◽

2002 ◽

Vol 123 (6) ◽

pp. 3434-3441 ◽

Cited By ~ 5

Author(s):

Sébastien Lépine ◽

Michael M. Shara ◽

R. Michael Rich

Keyword(s):

Nearby Stars

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