Speckle Interferometry of New and Problem [ITAL]HIPPARCOS[/ITAL][ITAL]Hipparcos[/ITAL] Binaries. II. Observations Obtained in 1998–1999 from M[CLC]c[/CLC]Donald Observatory

Mason, Brian D.; Hartkopf, William I.; Holdenried, E. R.; Rafferty, T. J.

doi:10.1086/321096

Cited by 78 publications

(47 citation statements)

References 40 publications

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“…The Hipparcos observations of o Per revealed the presence of a visual companion at a separation of 1.02 and with a magnitude difference of 2.91 mag. Speckle interferometry by Mason et al (2001) confirmed this detection. If this visual companion is physically related to o Per, and if we assume it to be a main-sequence star, its magnitude suggests a spectral type of ∼B4 and an estimated mass of ∼4−6 M .…”

Section: The B1 III Star O Persupporting

confidence: 56%

XMM-Newtonstudy of the very young stellar cluster IC 348

Preibisch¹,

Zinnecker²

2004

A&A

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Abstract. We analyze a XMM-Newton X-ray imaging observation of the very young stellar cluster IC 348 with an observing time of 12 h and a corresponding total (all detector) MOS-equivalent exposure time of 207 ks. Our observation is strongly affected by a very intense solar particle flare, due to which only the first half of the exposure time can be used for scientific analysis. We compare the X-ray sources seen by XMM-Newton with those found in our previous Chandra study of IC 348 and find that XMM-Newton reveals 71 new X-ray sources, most of which are located outside the field-of-view of the Chandra observation. 20 of these new X-ray sources can be identified with known cluster members, and 19 sources are likely to be new low-mass members of the cluster. The lightcurves of the XMM-Newton sources show at most moderate levels of variability, but no large flares. We compare the spectral fitting results for 10 stars for which we have good spectra from both Chandra and XMM-Newton, and find good agreement in the fitted plasma temperatures, but a systematic difference in the fitted values of the hydrogen column density (extinction). We finally discuss the X-ray properties of the optically bright B1 star o Per and the X-ray detections among the deeply embedded young stellar objects to the south of the optical cluster center (including HH 211-mm), and find that none of the 23 spectroscopically identified brown dwarfs in IC 348 is detected in our XMM-Newton data. Key words.Galaxy: open clusters and associations: individual: IC 348 -stars: formation -stars: coronaestars: low-mass, brown dwarfs -stars: pre-main sequence -X-rays: stars IntroductionIC 348 is a very young stellar cluster in the Perseus molecular cloud complex, associated with the Per OB2 association and located at a distance of about 310 pc (cf. Herbig 1998). The cluster is exceptionally well investigated in optical and infrared wavelengths. Several studies have identified cluster members by extensive spectroscopy and photometry at optical and IR wavelengths (cf. Herbig 1998;Lada & Lada 1995;Luhman et al. 1998;Luhman 1999) or narrow-band photometry (Najita et al. 2000). Studies of the infrared luminosity function have provided information on the stellar and sub-stellar mass function Muench et al. 2003;Preibisch et al. 2003). Recently, Luhman et al. (2003) presented a new census of the stellar and substellar members of IC 348. From spectroscopy of candidate cluster members they identified numerous new members, including several brown dwarfs. Their final, extinction-limited (A V ≤ 4 mag) sample of members is unbiased in mass, nearly complete down to masses of M ≥ 0.03 M , and contains 288 spectroscopically identified cluster members, including 23 brown dwarfs.The basic properties of IC 348 can be summarized as follows: the mean age of the cluster members is ∼2 Myr and most of the stars exhibit relatively low extinction (A V < ∼ 4 mag). The majority of the cluster members is in the T Tauri stage of premain sequence evolution, and more than 50 stars can be class...

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Section: The B1 III Star O Persupporting

confidence: 56%

XMM-Newtonstudy of the very young stellar cluster IC 348

Preibisch¹,

Zinnecker²

2004

A&A

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“…In their survey of the Solar neighbourhood, Nordström et al (2004) reported [Fe/H] = +0.33 for this star. Mason et al (2001) observed it twice using speckle-interferometry but found no evidence for multiplicity. However, the night-averaged CCF shows a slight and systematic bump on the left side of the main peak which could be related to the presence of a secondary component.…”

Section: Hd 68725 -Hip 40361mentioning

confidence: 99%

Search for pulsation among suspected A-type binaries and the new multiperiodic δ Scuti star HD 217860

Frémat

Lampens

Cauteren

et al. 2007

A&A

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Context. In the H-R diagram, the intersection of the main sequence and the classical Cepheid instability strip corresponds to a domain where a rich variety of atmospheric phenomena are at play (including pulsation, radiative diffusion, convection). Main-sequence A-type stars are among the best candidates to study the complex interplay between these various phenomena. Aims. We have explored a sample of suspected A-type binaries in a systematic way, both spectroscopically and photometrically. The sample consists of main-sequence A-type stars for which the few existing radial velocity measurements may show variability, but for which other essential information is lacking. Due to their location in the H-R diagram, indications of pulsation and/or chemical peculiarities among these suspected binary (or multiple) systems may be found. Methods. High-resolution spectroscopy obtained with the ELODIE and MUSICOS spectrographs was used in combination with a few nights of differential CCD photometry in order to search for pulsation(s). In order to search as well for chemical peculiarities or for possible hidden component(s), we derived the atmospheric stellar parameters by fitting the observed spectra with LTE synthetic ones. Results. Of the 32 investigated targets, eight are spectroscopic binaries, one of which is a close binary also showing eclipses, and three have been identified as δ Scuti pulsators with rapid line-profile variations. Conclusions. Among the latter stars, HD 217860 reveals interesting multiperiodic photometric and spectroscopic variations, with up to eight frequencies common to two large photometric data sets. We suggest that at least one radial overtone mode is excited among the two most dominant frequencies, on the basis of the computation of the pulsation constants as well as of the predicted frequencies and the expected behaviour of the amplitude ratio and the phase difference in two passbands using adequate theoretical modelling. We furthermore found evidence for a strong modulation of the amplitude(s) and/or the (radial) frequency content of this intriguing δ Scuti star.

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“…We identified 16 spectroscopic binaries (SB) in our sample of 81 solar twins by analyzing their radial velocities; some of these stars are reported as binaries by Tokovinin (2014a,b), Mason et al (2001), Baron et al (2015). We did not find previous reports of multiplicity for the stars HIP 30037, HIP 62039 and HIP 64673 in the literature.…”

Section: Binary Starsmentioning

confidence: 96%

The Solar Twin Planet Search

Santos

Meléndez

Nascimento

et al. 2016

A&A

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Context. It is still unclear how common the Sun is when compared to other similar stars in regards to some of its physical properties, such as rotation. Considering that gyrochronology relations are widely used today to estimate ages of stars in the main sequence, and that the Sun is used to calibrate it, it is crucial to assess whether these procedures are acceptable. Aims. We analyze the rotational velocities, limited by the unknown rotation axis inclination angle, of an unprecedented large sample of solar twins to study the rotational evolution of Sun-like stars, and assess whether the Sun is a typical rotator. Methods. We used high-resolution (R = 115 000) spectra obtained with the HARPS spectrograph and the 3.6 m telescope at La Silla Observatory. The projected rotational velocities for 81 solar twins were estimated by line profile fitting with synthetic spectra. Macroturbulence velocities were inferred from a prescription that accurately reflects their dependence with effective temperature and luminosity of the stars. Results. Our sample of solar twins include some spectroscopic binaries with enhanced rotational velocities, and we do not find any nonspectroscopic binaries with unusually high rotation velocities. We verified that the Sun does not have a peculiar rotation, but the solar twins exhibit rotational velocities that depart from the Skumanich relation. Conclusions. The Sun is a regular rotator when compared to solar twins with a similar age. Additionally, we obtain a rotational braking law that better describes the stars in our sample (v ∝ t −0.6 ) in contrast to previous, often-used scalings.

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Speckle Interferometry of New and Problem [ITAL]HIPPARCOS[/ITAL][ITAL]Hipparcos[/ITAL] Binaries. II. Observations Obtained in 1998–1999 from M[CLC]c[/CLC]Donald Observatory

Cited by 78 publications

References 40 publications

XMM-Newtonstudy of the very young stellar cluster IC 348

XMM-Newtonstudy of the very young stellar cluster IC 348

Search for pulsation among suspected A-type binaries and the new multiperiodic δ Scuti star HD 217860

The Solar Twin Planet Search

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