CHARM: A Catalog of High Angular Resolution Measurements

Richichi, A.; Percheron, Isabelle

doi:10.1051/0004-6361:20020236

Cited by 69 publications

(61 citation statements)

References 19 publications

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“…A total of about 60 measurements are listed in the CHARM Catalogue (Richichi & Percheron 2002), according to which Aldebaran is the star with the highest number of direct diameter determinations. Since Aldebaran is non-variable to a high degree of accuracy (photometric variations are known at a level ∆V < ∼ 0.01 mag and Based on observations collected at TIRGO (Gornergrat, Switzerland).…”

Section: Introductionmentioning

confidence: 99%

Aldebaran's angular diameter: How well do we know it?

Richichi

Roccatagliata

2005

A&A

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Abstract. The bright, well-known K5 giant Aldebaran, α Tau, is probably the star with the largest number of direct angular diameter determinations, achieved over a long time by several authors using various techniques. In spite of this wealth of data, or perhaps as a direct result of it, there is not a very good agreement on a single angular diameter value. This is particularly unsettling if one considers that Aldebaran is also used as a primary calibrator for some angular resolution methods, notably for optical and infrared long baseline interferometry. Directly connected to Aldebaran's angular diameter and its uncertainties is its effective temperature, which also has been used for several empirical calibrations. Among the proposed explanations for the elusiveness of an accurate determination of the angular diameter of Aldebaran are the possibility of temporal variations as well as a possible dependence of the angular diameter on the wavelength. We present here a few, very accurate new determinations obtained by means of lunar occultations and long baseline interferometry. We derive an average value of 19.96±0.03 milliarcsec for the uniform disk diameter. The corresponding limb-darkened value is 20.58 ± 0.03 milliarcsec, or 44.2 ± 0.9 R . We discuss this result, in connection with previous determinations and with possible problems that may affect such measurements.

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Section: Introductionmentioning

confidence: 99%

Aldebaran's angular diameter: How well do we know it?

Richichi

Roccatagliata

2005

A&A

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“…We determined the projected rotational velocity v rot sin i with the cross-correlation method as described in Queloz et al (1998) and using the velocity calibration value for FEROS measured by Melo et al (2001). The angular diameter Θ was taken from the CHARM catalogue (Richichi & Percheron 2002). Stellar RV measurements with FEROS were made using a simultaneous Th-Ar calibration technique.…”

Section: Introductionmentioning

confidence: 99%

Evidence of a sub-stellar companion around HD 47536

Setiawan

Hatzes

Lühe

et al. 2003

A&A

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Abstract.We report evidence of a low-mass companion around the K1III giant star HD 47536. This star belongs to our sample of 83 subgiant and giant stars studied for their radial velocity variations using the FEROS spectrograph at the 1.52 m-ESO telescope on La Silla. We find that the radial velocity of HD 47536 exhibits a periodic variation of about 712 days with a semiamplitude of 113 m s −1 . These variations are not accompanied by variations in either Ca II emission or in the spectral line shapes. A Keplerian orbit due to a sub-stellar companion is thus the most viable explanation for the radial velocity variation. Assuming a moderate stellar mass of m 1 = 1.1−3.0 M we obtain a minimum mass for the companion of m 2 sin i = 5.0−9.7 M Jup , an orbital semi-major axis of 1.6-2.3 AU, and an eccentricity of e = 0.2.

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“…We note that in the optical regime time-averaged data points are shown and their error bars indicate temporal variability. The data points are from the literature (Egret et al 1992;Kislyuk et al 2000;Zacharias et al 2004;Röser et al 2008;Zacharias et al 2012;Niels Bohr Institute et al 2014;Zacharias et al 2015;Morel & Magnenat 1978;Droege et al 2006;Henden et al 2016;Herbig & Bell 1988;Ahn et al 2012;Skiff 2014;Kraus et al 2011;Ayres 2010;Folha & Emerson 2001;Grankin et al 2007;Assafin et al 1996;Richichi & Percheron 2002;Richichi et al 2005;Connelley & Greene 2010;Cutri et al 2003;Bary et al 2009;Kóspál et al 2012;Luhman et al 2006;Cieza et al 2009;Salyk et al 2013;Cutri & et al 2014;Ishihara et al 2010;Yamamura et al 2010;Di Francesco et al 2008;Andrews et al 2013;Altenhoff et al 1994;Dzib et al 2015).…”

Section: Cold Absorbing Envelope In the Line Of Sightmentioning

confidence: 99%

Mid-infrared interferometric variability of DG Tauri: Implications for the inner-disk structure

Varga

Gabányi

Ábrahám

et al. 2017

A&A

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Context. DG Tau is a low-mass pre-main sequence star, whose strongly accreting protoplanetary disk exhibits a so-far enigmatic behavior: its mid-infrared thermal emission is strongly time-variable, even turning the 10 µm silicate feature from emission to absorption temporarily. Aims. We look for the reason for the spectral variability at high spatial resolution and at multiple epochs. Methods. Infrared interferometry can spatially resolve the thermal emission of the circumstellar disk, also giving information about dust processing. We study the temporal variability of the mid-infrared interferometric signal, observed with the VLTI/MIDI instrument at six epochs between 2011 and 2014. We fit a geometric disk model to the observed interferometric signal to obtain spatial information about the disk. We also model the mid-infrared spectra by template fitting to characterize the profile and time dependence of the silicate emission. We use physically motivated radiative transfer modeling to interpret the mid-infrared interferometric spectra. Results. The inner disk (r < 1 − 3 au) spectra exhibit a 10 µm absorption feature related to amorphous silicate grains. The outer disk (r > 1 − 3 au) spectra show a crystalline silicate feature in emission, similar to the spectra of comet Hale-Bopp. The striking difference between the inner and outer disk spectral feature is highly unusual among T Tauri stars. The mid-infrared variability is dominated by the outer disk. The strength of the silicate feature changed by more than a factor of two. Between 2011 and 2014 the half-light radius of the mid-infrared-emitting region decreased from 1.15 to 0.7 au. Conclusions. For the origin of the absorption we discuss four possible explanations: a cold obscuring envelope, an accretion heated inner disk, a temperature inversion on the disk surface and a misaligned inner geometry. The silicate emission in the outer disk can be explained by dusty material high above the disk plane, whose mass can change with time, possibly due to turbulence in the disk.

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CHARM: A Catalog of High Angular Resolution Measurements

Cited by 69 publications

References 19 publications

Aldebaran's angular diameter: How well do we know it?

Aldebaran's angular diameter: How well do we know it?

Evidence of a sub-stellar companion around HD 47536

Mid-infrared interferometric variability of DG Tauri: Implications for the inner-disk structure

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