scholarly journals KELT-17: a chemically peculiar Am star and a hot-Jupiter planet

2020 ◽  
Vol 641 ◽  
pp. A145
Author(s):  
C. Saffe ◽  
P. Miquelarena ◽  
J. Alacoria ◽  
J. F. González ◽  
M. Flores ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Balmer Line ◽  
Stellar Radius ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Chemical Pattern ◽  
Chemically Peculiar Stars ◽  
Hot Jupiter

Context. There is very little information to be found in the literature regarding the detection of planets orbiting chemically peculiar stars. Aims. Our aim is to determine the detailed chemical composition of the remarkable planet host star KELT-17. This object hosts a hot-Jupiter planet with 1.31 MJup detected by transits, and it is one of the more massive and rapidly rotating planet hosts seen to date. We set out to derive a complete chemical pattern for this star, in order to compare it with those of chemically peculiar stars. Methods. We carried out a detailed abundance determination in the planet host star KELT-17 via spectral synthesis. Stellar parameters were estimated iteratively by fitting Balmer line profiles and imposing the Fe ionization balance using the SYNTHE program together with plane-parallel ATLAS12 model atmospheres. Specific opacities for an arbitrary composition and microturbulence velocity vmicro were calculated through the opacity sampling (OS) method. The abundances were determined iteratively by fitting synthetic spectra to metallic lines of 16 different chemical species using SYNTHE. The complete chemical pattern of KELT-17 was compared to the recently published average pattern of Am stars. We estimated the stellar radius using two methods: a) comparing the synthetic spectral energy distribution with the available photometric data and the Gaia parallax, and b) using a Bayesian estimation of stellar parameters using stellar isochrones. Results. We found over-abundances of Ti, Cr, Mn, Fe, Ni, Zn, Sr, Y, Zr, and Ba, together with subsolar values of Ca and Sc. Notably, the chemical pattern agrees with those recently published for Am stars, making KELT-17 the first exoplanet host whose complete chemical pattern is unambiguously identified with this class. The stellar radius derived by two different methods agrees to each other and with those previously obtained in the literature.

scholarly journals A Magnetic Snapshot Survey of F-Type Stars

2020 ◽  
Author(s):  
J M Seach ◽  
S C Marsden ◽  
B D Carter ◽  
C Neiner ◽  
C P Folsom ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Longitudinal Magnetic Field ◽  
Convection Zone ◽  
Stellar Radius ◽  
Spectral Class ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
The Mean ◽  
Chemically Peculiar Stars ◽  
F Stars

Abstract We present a spectropolarimetric magnetic snapshot survey of 55 stars which includes 53 F-type stars ranging from spectral types F0 to F9 plus 2 chemically peculiar stars β CrB, and δ Cap. We look for magnetic fields in stars spanning a range of effective temperatures where the transition from fossil to dynamo magnetic fields is believed to occur. High-resolution spectropolarimetry using circularly polarized spectra is used to look for a magnetic detection in the Stokes V profile, determine the mean longitudinal magnetic field (Bl), and to look for correlations with stellar parameters. Surface magnetic fields are detected on 14 F-stars, and present in every spectral class from F3V-F9V ranging in strength from 0.3 ± 0.1 G (36 UMa, F8V) to 8.3 ± 0.9 G (h Dra, F8V). Thus we find photospheric magnetic fields are present in stars as early as spectral type F3V with an outer convection zone thickness less than a few per cent of the stellar radius.

scholarly journals Project VeSElkA : Preliminary results for CP stars recently observed with ESPaDOnS

2014 ◽  
Vol 9 (S307) ◽  
pp. 381-382
Author(s):  
Viktor Khalack ◽  
Francis LeBlanc
Keyword(s):  
Effective Temperature ◽  
Stellar Atmosphere ◽  
Balmer Line ◽  
Line Profiles ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
First Results ◽  
Chemically Peculiar Stars ◽  
The Phoenix ◽  
Temperature Surface

AbstractWe present the first results for the estimation of gravity and effective temperature of poorly studied chemically peculiar stars recently observed with the spectropolarimeter ESPaDOnS at CFHT in the frame of the VeSElkA (Vertical Stratification of Elements Abundance) project. A grid of theoretical stellar atmosphere models with the corresponding fluxes has been calculated using the PHOENIX code. We have used these fluxes to fit Balmer line profiles employing the code FITSB2 that produces estimates of the effective temperature, surface gravity and radial velocity for each star.

scholarly journals A 3-D look into the atmosphere?

2009 ◽  
Vol 5 (H15) ◽  
pp. 151-160
Author(s):  
G. A. Wade ◽  
L. Mashonkina ◽  
T. Ryabchikova ◽  
J. Krticka ◽  
J. Silvester ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spectral Synthesis ◽  
Surface Structures ◽  
Atmospheric Models ◽  
Physical Processes ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Stellar Pulsations ◽  
Magnetic Stars ◽  
Chemically Peculiar Stars

AbstractThe atmospheres of chemically peculiar stars can be highly structured in both the horizontal and vertical dimensions. While most prevalent in the magnetic stars, these structures can also exist in non-magnetic stars. In addition to providing an important window to understanding the physical processes at play in these complex atmospheres, they can also be exploited to study stellar pulsations. This article reviews contributions to the session “A 3D look into the atmosphere” of the Joint Discussion “Progress in understanding the physics of Ap and related stars”. It is divided into 3 sections: “Magnetic field and surface structures”, “Pulsations in the atmospheres of roAp stars/inversions”, and “Spectral synthesis/atmospheric models”.

scholarly journals On-line database of photometric observations of magnetic chemically peculiar stars

2007 ◽  
Vol 328 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Z. Mikulášek ◽  
J. Janík ◽  
J. Zverko ◽  
J. Žižňovský ◽  
M. Zejda ◽  
...  
Keyword(s):  
Chemically Peculiar ◽  
Photometric Observations ◽  
Peculiar Stars ◽  
On Line ◽  
Chemically Peculiar Stars

scholarly journals Advanced test of the model stellar atmospheres: the nature of the light variability of magnetic chemically peculiar stars

2008 ◽  
Vol 4 (S252) ◽  
pp. 347-348
Author(s):  
J. Krtička ◽  
Z. Mikulášek ◽  
J. Zverko ◽  
J. Žižňovský ◽  
P. Zvěřina
Keyword(s):  
Chemical Elements ◽  
Horizontal Distribution ◽  
Stellar Atmospheres ◽  
Silicon Iron ◽  
Surface Distribution ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Distribution Of Elements ◽  
Chemically Peculiar Stars ◽  
Light Variability

AbstractThe magnetic chemically peculiar stars exhibit both inhomogeneous horizontal distribution of chemical elements on their surfaces and the light variability. We show that the observed light variability of these stars can be successfully simulated using models of their stellar atmospheres and adopting the observed surface distribution of elements. The most important elements that influence the light variability are silicon, iron, and helium.

scholarly journals 29. Stellar Spectra

1982 ◽  
Vol 18 (1) ◽  
pp. 343-360 ◽  
Author(s):  
W.K. Bonsack
Keyword(s):  
Stellar Evolution ◽  
Working Group ◽  
Main Sequence ◽  
Symbiotic Stars ◽  
Be Stars ◽  
Stellar Spectra ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Chemically Peculiar Stars ◽  
Ap Stars

During the interval covered by this report, Commission 29 has sponsored or cosponsored the following IAU meetings: Symposium 98 on “Be Stars,” Munich, FRG, April 1981; Colloquium 59, “Effects of Mass-Loss on Stellar Evolution,” Trieste, Italy, September 1980; and Colloquim 70, “The Nature of Symbiotic Stars,” Haute-Provence, France, August 1981. In addition, Commission 29, through its Working Group on Ap Stars, collaborated in the organization of the 23rd Liege International Astrophysical Symposium on Upper Main-Sequence Chemically Peculiar Stars. Several IAU symposia and colloquia proposed for 1982 and 1983 are also cosponsored by Commission 29.

scholarly journals K2 space photometry reveals rotational modulation and stellar pulsations in chemically peculiar A and B stars

2018 ◽  
Vol 616 ◽  
pp. A77 ◽  
Author(s):  
D. M. Bowman ◽  
B. Buysschaert ◽  
C. Neiner ◽  
P. I. Pápics ◽  
M. E. Oksala ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Intrinsic Variability ◽  
B Stars ◽  
Pulsating Stars ◽  
Chemically Peculiar ◽  
Large Scale Magnetic Field ◽  
Peculiar Stars ◽  
Show Evidence ◽  
Chemically Peculiar Stars

Context. The physics of magnetic hot stars and how a large-scale magnetic field affects their interior properties is largely unknown. Few studies have combined high-quality observations and modelling of magnetic pulsating stars, known as magneto-asteroseismology, primarily because of the dearth of detected pulsations in stars with a confirmed and well-characterised large-scale magnetic field. Aims. We aim to characterise observational signatures of rotation and pulsation in chemically peculiar candidate magnetic stars using photometry from the K2 space mission. Thus, we identify the best candidate targets for ground-based, optical spectropolarimetric follow-up observations to confirm the presence of a large-scale magnetic field. Methods. We employed customised reduction and detrending tools to process the K2 photometry into optimised light curves for a variability analysis. We searched for the periodic photometric signatures of rotational modulation caused by surface abundance inhomogeneities in 56 chemically peculiar A and B stars. Furthermore, we searched for intrinsic variability caused by pulsations (coherent or otherwise) in the amplitude spectra of these stars. Results. The rotation periods of 38 chemically peculiar stars are determined, 16 of which are the first determination of the rotation period in the literature. We confirm the discovery of high-overtone roAp pulsation modes in HD 177765 and find an additional 3 Ap and Bp stars that show evidence of high-overtone pressure modes found in roAp stars in the form of possible Nyquist alias frequencies in their amplitude spectra. Furthermore, we find 6 chemically peculiar stars that show evidence of intrinsic variability caused by gravity or pressure pulsation modes. Conclusions. The discovery of pulsations in a non-negligible fraction of chemically peculiar stars make these stars high-priority targets for spectropolarimetric campaigns to confirm the presence of their expected large-scale magnetic field. The ultimate goal is to perform magneto-asteroseismology and probe the interior physics of magnetic pulsating stars.

Sign in / Sign up

Export Citation Format

Share Document