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The Near-Infrared Size-Luminosity Relations for Herbig Ae/Be Disks
We report the results of a sensitive K-band survey of Herbig Ae/Be disksizes using the 85 m baseline Keck Interferometer. Targets were chosento span the maximum range of stellar properties to probe the disk sizedependence on luminosity and effective temperature. For most targets,the measured near-infrared sizes (ranging from 0.2 to 4 AU) support asimple disk model possessing a central optically thin (dust-free)cavity, ringed by hot dust emitting at the expected sublimationtemperatures (Ts~1000-1500 K). Furthermore, we find a tightcorrelation of disk size with source luminosity R~L1/2 for Aeand late Be systems (valid over more than two decades in luminosity),confirming earlier suggestions based on lower quality data.Interestingly, the inferred dust-free inner cavities of the highestluminosity sources (Herbig B0-B3 stars) are undersized compared topredictions of the ``optically thin cavity'' model, likely because ofoptically thick gas within the inner AU.
| UBV(RI)C photometric monitoring of Orion population stars in the Southern Hemisphere
UBV(RI)C photometry on a sample of southern T Tauri stars, selected fromthe Herbig and Bell (1988) catalog, is reported and four new candidates(AS 205, Wa Oph/2, Wa Oph/3, and Wa CrA/2) for rotational modulation aresingled out from the sample. The color trend for the stars showingvariability is considered. Typically, colors become redder when the staris fainter, complying with the general behavior observed in T Tauristars. This can be interpreted as due to the (variable) presence ofsurface inhomogeneities (either dark or bright) or, in some cases, itcould also be consistent with the hypothesis of variable circumstellarextinction. Estimates of gross spot properties (e.g., temperature andfilling factor) are derived for the four stars showing possibleperiodicity, from the amplitudes of the variations observed at differentwavelengths, by use of a simple blackbody model.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yilanci |
| Sað Açýklýk: | 16h33m51.04s |
| Yükselim: | -24°17'26.0" |
| Görünürdeki Parlaklýk: | 8.647 |
| Uzaklýk: | 122.699 parsek |
| özdevim Sað Açýklýk: | -56.2 |
| özdevim Yükselim: | -31.4 |
| B-T magnitude: | 9.498 |
| V-T magnitude: | 8.718 |
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