The TIRGO Lunar Occultation Program: Summary of the 1985-1995 Observations

Richichi, A.; Baffa, C.; Calamai, G.; Lisi, F.

doi:10.1086/118221

Cited by 62 publications

(91 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, there is some ambiguity about this direction in the original paper. Interestingly enough, both lunar occultation data (Richichi et al 1995) and Come-On+ adaptive-optics observations (Cruzalèbes et al 1998) claim as well that the source is asymmetric. The September 1994 ComeOn+ observations in the K band clearly reveal a secondary source 0.35 to the SW (with a position angle of 241 • ) of the primary source, with a flux ratio of 2%.…”

Section: Tx Pscmentioning

confidence: 90%

X Herculis and TX Piscium: two cases of ISM interaction with stellar winds observed byHerschel

Jorissen

Mayer

Eck

et al. 2011

A&A

View full text Add to dashboard Cite

The asymptotic giant branch (AGB) stars X Her and TX Psc have been imaged at 70 and 160 μm with the PACS instrument onboard the Herschel satellite, as part of the large MESS (Mass loss of Evolved StarS) guaranteed time key program. The images reveal an axisymmetric extended structure with its axis oriented along the space motion of the stars. This extended structure is very likely to be shaped by the interaction of the wind ejected by the AGB star with the surrounding interstellar medium (ISM). As predicted by numerical simulations, the detailed structure of the wind-ISM interface depends upon the relative velocity between star+wind and the ISM, which is large for these two stars (108 and 55 km s −1 for X Her and TX Psc, respectively). In both cases, there is a compact blob upstream whose origin is not fully elucidated, but that could be the signature of some instability in the wind-ISM shock. Deconvolved images of X Her and TX Psc reveal several discrete structures along the outermost filaments, which could be Kelvin-Helmholtz vortices. Finally, TX Psc is surrounded by an almost circular ring (the signature of the termination shock?) that contrasts with the outer, more structured filaments. A similar inner circular structure seems to be present in X Her as well, albeit less clearly.

show abstract

Section: Tx Pscmentioning

confidence: 90%

X Herculis and TX Piscium: two cases of ISM interaction with stellar winds observed byHerschel

Jorissen

Mayer

Eck

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…Some results have been revisited, such as those of TX Psc and Y Tau (see e.g. Richichi et al 1995). Part of the observations have been made in the visible but most were in the near infrared, typically through the H and K-filters (centered at 1.65 and 2.2 µm respectively).…”

Section: The Observed Angular Diametersmentioning

confidence: 99%

The effective temperatures of carbon-rich stars

Bergeat

Knapik

Rutily

2001

A&A

151

207

View full text Add to dashboard Cite

Abstract. We evaluate effective temperatures of 390 carbon-rich stars. The interstellar extinction on their lines of sights was determined and circumstellar contributions derived. The intrinsic (dereddened) spectral energy distributions (SEDs) are classified into 14 photometric groups (HCi, CVj and SCV with i = 0,5 and j = 1,7). The new scale of effective temperatures proposed here is calibrated on the 54 angular diameters (measured on 52 stars) available at present from lunar occultations and interferometry. The brightness distribution on stellar discs and its influence on diameter evaluations are discussed. The effective temperatures directly deduced from those diameters correlate with the classification into photometric groups, despite the large error bars on diameters. The main parameter of our photometric classification is thus effective temperature. Our photometric k 1/2 coefficients are shown to be angular diameters on a relative scale for a given photometric group, (more precisely for a given effective temperature). The angular diameters are consistent with the photometric data previously shown to be consistent with the true parallaxes from HIPPARCOS observations (Knapik, et al. 1998, Sect. 6). Provisional effective temperatures, as constrained by a successful comparison of dereddened SEDs from observations to model atmosphere predictions, are in good agreement with the values directly calculated from the observed angular diameters and with those deduced from five selected intrinsic color indices. These three approaches were used to calibrate a reference angular diameter Φ0 and the associated coefficient CT eff . The effective temperature proposed for each star is the arithmetic mean of two estimates, one ("bolometric") from a reference integrated flux F0, the other ("spectral") from calibrated color indices which are representative of SED shapes. Effective temperatures for about 390 carbon stars are provided on this new homogeneous scale, together with values for some stars classified with oxygen-type SEDs with a total of 438 SEDs (410 stars) studied. Apparent bolometric magnitudes are given. Objects with strong infrared excesses and optically thick circumstellar dust shells are discussed separately. The new effective temperature scale is shown to be compatible and (statistically) consistent with the sample of direct values from the observed angular diameters. The effective temperatures are confirmed to be higher than the mean color temperatures (from 140 to 440 K). They are in good agreement with the published estimates from the infrared flux method for T eff ≥ 3170 K, while an increasing discrepancy is observed toward lower temperatures. As an illustration of the efficiency of the photometric classification and effective temperature scale, the C/O ratios and the Merrill-Sanford (M-S) band intensities are investigated. It is shown that the maximum value, mean value and dispersion of C/O increase along the photometric CV-sequence, i.e. with decreasing effective temperature. The M-S bands of SiC2 are sho...

show abstract

“…Only a limited number of cases have been used to actually measure limb darkening from interferometric data (e.g., Burns et al 1997;Perrin et al 2004;Aufdenberg et al 2006;Wittkowski et al 2006). The same is true for observations of lunar occultation of stars, which only rarely yield limb-darkening measurements (Richichi & Lisi 1990). …”

Section: Introductionmentioning

confidence: 73%

OGLE 2008–BLG–290: an accurate measurement of the limb darkening of a galactic bulge K Giant spatially resolved by microlensing

Fouqué

Heyrovsky

Dong

et al. 2010

A&A

View full text Add to dashboard Cite

Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event.Aims. In high-magnification events, the lens caustic may cross over the source disk, which allows determination of the angular size of the source and measurement of its limb darkening. Methods. When such extended-source effects appear close to maximum magnification, the resulting light curve differs from the characteristic Paczyński point-source curve. The exact shape of the light curve close to the peak depends on the limb darkening of the source. Dense photometric coverage permits measurement of the respective limb-darkening coefficients.Results. In the case of the microlensing event OGLE 2008-BLG-290, the K giant source star reached a peak magnification at about 100. Thirteen different telescopes have covered this event in eight different photometric bands. Subsequent light-curve analysis yielded measurements of linear limb-darkening coefficients of the source in six photometric bands. The best-measured coefficients lead to an estimate of the source effective temperature of about 4700 +100 −200 K. However, the photometric estimate from colour-magnitude diagrams favours a cooler temperature of 4200 ± 100 K. Conclusions. Because the limb-darkening measurements, at least in the CTIO/SMARTS2 V s -and I s -bands, are among the most accurate obtained, the above disagreement needs to be understood. A solution is proposed, which may apply to previous events where such a discrepancy also appeared.

show abstract

The TIRGO Lunar Occultation Program: Summary of the 1985-1995 Observations

Cited by 62 publications

References 0 publications

X Herculis and TX Piscium: two cases of ISM interaction with stellar winds observed byHerschel

X Herculis and TX Piscium: two cases of ISM interaction with stellar winds observed byHerschel

The effective temperatures of carbon-rich stars

OGLE 2008–BLG–290: an accurate measurement of the limb darkening of a galactic bulge K Giant spatially resolved by microlensing

Contact Info

Product

Resources

About