Study of Chemically Peculiar Stars-I : High-resolution Spectroscopy and K2 Photometry of Am Stars in the Region of M44

Abstract

We present a study based on the high-resolution spectroscopy and K2 space photometry of five chemically peculiar stars in the region of the open cluster M44. The analysis of the high-precision photometric K2 data reveals that the light variations in HD 73045 and HD 76310 are rotational in nature and caused by spots or cloud-like co-rotating structures, which are non-stationary and short-lived. The time-resolved radial velocity measurements, in combination with the K2 photometry, confirm that HD 73045 does not show any periodic variability on timescales shorter than 1.3 d, contrary to previous reports in the literature. In addition to these new rotational variables, we discovered a new heartbeat system, HD 73619, where no pulsational signatures are seen. The spectroscopic and spectropolarimetric analyses indicate that HD 73619 belongs to the peculiar Am class, with either a weak or no magnetic field considering the 200 G detection limit of our study. The Least-Squares Deconvolution (LSD) profiles for HD 76310 indicate a complex structure in its spectra suggesting that this star is either part of a binary system or surrounded by a cloud shell. When placed in the Hertzsprung-Russell diagram, all studied stars are evolved from main-sequence and situated in the $\delta$ Scuti instability strip. The present work is relevant for further detailed studies of CP stars, such as inhomogeneities (including spots) in the absence of magnetic fields and the origin of the pulsational variability in heartbeat systems.

arXiv commentAccepted for publication in MNRAS

References in corpus (76)

• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• The K2 Mission: Characterization and Early results
• Understanding the Lomb-Scargle Periodogram
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• A box-fitting algorithm in the search for periodic transits
• A Computational Guide to Physics of Eclipsing Binaries. Paper I. Demonstrations and Perspectives
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• Rotation Periods of 34,030 Kepler Main-Sequence Stars: The Full Autocorrelation Sample
• HERMES: a high-resolution fibre-fed spectrograph for the Mercator telescope
• Measuring the rotation period distribution of field M-dwarfs with Kepler
• Kepler Eclipsing Binary Stars. VII. The Catalog of Eclipsing Binaries Found in the Entire Kepler Data-Set
• Least squares deconvolution of the stellar intensity and polarization spectra
• The Stellar Populations of Praesepe and Coma Berenices
• Rotation and magnetism of Kepler pulsating solar-like stars. Towards asteroseismically calibrated age-rotation relations
• CoRoT reveals a magnetic activity cycle in a Sun-like star
• Theoretical isochrones in several photometric systems II. The Sloan Digital Sky Survey ugriz system
• Determining global parameters of the oscillations of solar-like stars
• A Class of Eccentric Binaries with Dynamic Tidal Distortions Discovered with Kepler
• Master Robotic Net
• KOI-54: The Kepler Discovery of Tidally-Excited Pulsations and Brightenings in a Highly Eccentric Binary
• K2SC: Flexible systematics correction and detrending of K2 light curves using Gaussian Process regression
• {\em Gaia}-derived luminosities of {\em Kepler} A/F stars and the pulsator fraction across the δ Scuti instability strip
• Magnetic activity of F stars observed by Kepler
• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• KIC 4544587: an Eccentric, Short Period Binary System with delta Sct Pulsations and Tidally Excited Modes
• Surface rotation and photometric activity for Kepler targets I. M and K main-sequence stars
• Heartbeat Stars, Tidally Excited Oscillations, and Resonance Locking
• Dynamical Tides in Eccentric Binaries and Tidally-Excited Stellar Pulsations in KEPLER KOI-54
• Pulsating red giant stars in eccentric binary systems discovered from Kepler space-based photometry
• Atomic and Molecular Data for Optical Stellar Spectroscopy
• Precise time-series photometry for the Kepler-2.0 mission
• The first view of $\delta$ Scuti and $\gamma$ Doradus stars with the TESS mission
• Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter
• Tidal asteroseismology: Kepler's KOI-54
• Tidal Excitation of Modes in Binary Systems with Applications to Binary Pulsars
• Surface rotation of Kepler red giant stars
• Discovery and analysis of p-mode and g-mode oscillations in the A-type primary of the eccentric binary HD 209295
• Detection of a weak surface magnetic field on Sirius A: are all tepid stars magnetic ?
• The effect of rotation on the abundances of the chemical elements of the A-type stars in the Praesepe cluster
• Rotation periods and seismic ages of KOIs - comparison with stars without detected planets from Kepler observations
• Late stages of the evolution of A-type stars on the main sequence: comparison between observed chemical abundances and diffusion models for 8 Am stars of the Praesepe cluster
• Fundamental parameters of Be stars located in the seismology fields of COROT
• Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades
• HD 174884: a strongly eccentric, short-period early-type binary system discovered by CoRoT
• Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP
• KIC 8164262: a Heartbeat Star Showing Tidally Induced Pulsations with Resonant Locking
• KIC 3749404: A heartbeat Star with Rapid Apsidal Advance Indicative of a Tertiary Component
• K2 space photometry reveals rotational modulation and stellar pulsations in chemically peculiar A and B stars
• Gaia luminosities of pulsating A-F stars in the Kepler field
• Spots on Am stars
• Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227
• Discovery of a very weak magnetic field on the Am star Alhena
• First discovery of a magnetic field in a main sequence delta Scuti star: the Kepler star HD188774
• The Nainital-Cape Survey-III : A Search for Pulsational Variability in Chemically Peculiar Stars
• It takes a village to raise a tide: nonlinear multiple-mode coupling and mode identification in KOI-54
• Starspot signature on the light curve: Learning about the latitudinal distribution of spots
• Discovery of starspots on Vega - First spectroscopic detection of surface structures on a normal A-type star
• Tidally Excited Oscillations in Heartbeat Binary Stars: Pulsation Phases and Mode Identification
• The Nainital-Cape Survey-IV
• Highlights of Discoveries for $\delta$ Scuti Variable Stars From the Kepler Era
• Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480
• A photometric study of chemically peculiar stars with the STEREO satellites. II. Non-magnetic chemically peculiar stars
• Discovery of a magnetic field in $\rho$ Pup
• Multi-technique investigation of the binary fraction among A-F type candidate hybrid variable stars discovered by Kepler
• Time-resolved photometric and spectroscopic analysis of a luminous Ap star HD103498
• Astrokit -- an Efficient Program for High-Precision Differential CCD Photometry and Search for Variable Stars
• A spectroscopic analysis of the chemically peculiar star HD207561
• High-resolution Spectroscopy and Spectropolarimetry of Selected Delta Scuti Pulsating Variables
• Rotation and spots in normal A and Am/Fm stars
• The Weird Detector: Flagging periodic, coherent signals of arbitrary shape in time series photometry
• On the relation between active-region lifetimes and the autocorrelation function of light curves
• HERMES spectroscopy of normal A and Am stars
• Modelling high resolution Echelle spectrographs for calibrations: Hanle Echelle spectrograph, a case study
• Ultra weak magnetic fields in Am stars: Beta UMa and theta Leo
• Modelling the chemical evolution of the Milky Way

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• Indo-Belgian co-operation in Astrophysics: From inception to future prospects
• High-precision K2/TESS Photometry and HERMES Spectroscopy of Four Bright Field Stars
• Unveiling the Variability and Chemical Composition of AL Col
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