相关论文: The Discovery of lambda Bootis Stars -- The Southe…

Lambda Boo stars are predominately A-type stars with solar abundant C, N, O, and S, but up to 2 dex underabundances of refractory elements. The stars' unusual surface abundances could be due to a selective accretion of volatile gas over…

We have analysed around 170 000 individual photometric WASP measurements of 15 well established lambda Bootis stars to search for variability. The lambda Bootis stars are a small group of late-B to early-F, Pop. I, stars that show moderate…

$\lambda$ Bo\"otis stars are a subset of chemically peculiar A-stars that display Solar abundances in lighter elements (C, N, O, S, etc.) but a deficiency in Iron-peak elements. This difference has been attributed to the A-stars accreting…

Our goal is to find new candidate lambda Boo stars that belong to binary systems. A detailed abundance determination of some candidates could confirm their true lambda Boo nature, while the composition of eventual late-type companions could…

Within a project to investigate the properties of lambda Bootis stars, we report on their abundance pattern. High resolution spectra have been obtained for a total of twelve candidate lambda Bootis stars, four of them being contained in…

We publish here the second part of our spectroscopic survey at high dispersion of some known and suspected lambda Bootis stars with a view to detecting circumstellar shell features. Eight stars of our sample exhibit such features. These…

The group of lambda Bootis type stars comprises late B- to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. One of the theories to explain…

We examine the large sample of lambda Boo candidates collected in Table 1 of Gerbaldi et al. (2003) to see how many of them show composite spectra. Of the 132 lambda Boo candidates we identify 22 which definitely show composite spectra and…

We analyse TESS light curves for 70 southern $\lambda$ Boo stars to identify binaries and to determine which of them pulsate as $\delta$ Scuti stars. We find two heartbeat stars and two eclipsing binaries among the sample. We calculate that…

The abundance anomalies in lambda Boo stars are popularly explained by element-specific mass inflows at rates that are much greater than empirically-inferred bounds for interstellar accretion. Therefore, a lambda Boo star's thin outer…

The literature on the $\lambda$ Boo stars has grown to become somewhat heterogenous, as different authors have applied different criteria across the UV, optical and infrared regions to determine the membership status of $\lambda$ Boo…

We present high-resolution Magellan/MIKE spectra of the four brightest confirmed red giant stars in the ultra-faint dwarf galaxy Bootes II (Boo II). These stars all inhabit the metal-poor tail of the Boo II metallicity distribution…

The origin of lambda Boo stars is currently unknown. After several efforts by many authors, no bona fide lambda Boo stars have been confirmed as members of open clusters. Their detection could provide an important test bed for a detailed…

We have completed a high-resolution, high-signal-to-noise, spectroscopic survey of the northern members of the peculiar lambda Boo stars in order to investigate the frequency of the incidence of nonradial pulsation (NRP) in these…

In the attempt to shed new light on the lambda Boo phenomenon we analyzed the astrometric, photometric and spectroscopic characteristics of stars out of a list of recently selected lambda Boo candidates. We show that the class is still…

Most of the current theories suggest the lambda Bootis phenomenon to originate from an interaction between the stellar surface and its local environment. In this paper, we compare the abundance pattern of the lambda Bootis stars to that of…

The lambda Bootis stars, a group of late B to early F-type population I stars, have surface abundances that resemble the general metal depletion pattern found in the interstellar medium. Inspired by the recent result that the fundamental…

The lambda Bootis stars are Population I, late B to early F-type stars, with moderate to extreme (up to a factor 100) surface underabundances of most Fe-peak elements and solar abundances of lighter elements (C, N, O, and S). To put…

High angular resolution observations have shown that some stars classified as lambda Boo are binaries with low values of angular separation and magnitude difference of the components; therefore the observed spectrum of these objects is a…

The lambda Bootis (LB) stars are located at the upper main sequence of the H-R diagram and exhibit a peculiar abundance pattern. The light elements (C, N, O, and S) present solar abundances whereas all other elements are moderately to…