Analysis of correlations between polarimetric and photometric
 characteristics of young stars

Yudin, R. V.

doi:10.1051/aas:2000343

Cited by 38 publications

(41 citation statements)

References 42 publications

(71 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This suggests the presence of a possible envelope as well as a circumstellar disk, or possibly a flared disk. The polarization is 4.7% (Yudin 2000).…”

Section: Eliasmentioning

confidence: 97%

Close binary companions of the HAeBe stars LkHα198, Elias 1, HK Ori and V380 Ori

Smith¹,

Balega

Duschl

et al. 2005

A&A

View full text Add to dashboard Cite

Abstract. We present diffraction-limited bispectrum speckle interferometry observations of four well-known Herbig Ae/Be (HAeBe) stars, LkHα 198, Elias 1, HK Ori and V380 Ori. For two of these, LkHα 198 and Elias 1, we present the first unambiguous detection of close companions. The plane of the orbit of the new LkHα 198 companion appears to be significantly inclined to the plane of the circumprimary disk, as inferred from the orientation of the outflow. We show that the Elias 1 companion may be a convective star, and suggest that it could therefore be the true origin of the X-ray emission from this object. In the cases of HK Ori and V380 Ori, we present new measurements of the relative positions of already-known companions, indicating orbital motion. For HK Ori, photometric measurements of the brightness of the individual components in four bands allowed us to decompose the system spectral energy distribution (SED) into the two separate component SEDs. The primary exhibits a strong infrared excess which suggests the presence of circumstellar material, whereas the companion can be modelled as a naked photosphere. The infrared excess of HK Ori A was found to contribute around two thirds of the total emission from this component, suggesting that accretion power contributes significantly to the flux. Submillimetre constraints mean that the circumstellar disk cannot be particularly massive, whilst the near-infrared data indicates a high accretion rate. Either the disk lifetime is very short, or the disk must be seen in an outburst phase.

show abstract

“…This suggests the presence of a possible envelope as well as a circumstellar disk, or possibly a flared disk. The polarization is 4.7% (Yudin 2000).…”

Section: Eliasmentioning

confidence: 97%

Close binary companions of the HAeBe stars LkHα198, Elias 1, HK Ori and V380 Ori

Smith¹,

Balega

Duschl

et al. 2005

A&A

View full text Add to dashboard Cite

show abstract

“…Such a large NIR excess is often associated with polarised emission from the circumstellar matter (Yudin 2000), but Hales et al (2006) did not find any polarised emission and concluded that the disk may be too small to be resolved in their UKIRT observations. The decomposition of the N-band spectrum shows evidence of dust at a very early stage of processing.…”

Section: Hd 143 006mentioning

confidence: 99%

Mid-IR observations of circumstellar disks

Schuetz¹,

Meeus

Sterzik³

et al. 2009

A&A

View full text Add to dashboard Cite

We present new mid-infrared spectra of 15 targets (1 FU Orionis object, 4 Herbig Ae stars, 5 T Tauri stars, and 5 Vega-type stars), obtained with the TIMMI2 camera at La Silla Observatory (ESO). Three targets are members of the β Pic moving group (HD 155 555, HD 181 296, and HD 319 139). PAH bands are observed towards the T Tauri star HD 34 700 and the Herbig Ae star PDS 144 N. For HD 34 700, the band profiles indicate processed PAHs. The spectrum of the Vega-type object η Corvi (HD 109 085), for which a resolved disk at sub-mm wavelengths is known, appears stellar between 8-13 μm, but a small excess emission was reported by Spitzer observations. Similarly, no indication of circumstellar matter at mid-infrared wavelengths is found towards the Vega-like stars HD 3003, HD 80 951, HD 181 296, and, surprisingly, the T Tauri system HD 155 555. The silicate emission features of the remaining eight sources are modelled with a mixture of silicates of different grain sizes and composition. Unprocessed dust dominates FU Ori, HD 143 006, and CD-43 344. Large amorphous grains are the main dust component around HD 190 073, HD 319 139, KK Oph, and PDS 144 S. Both small grains and crystalline dust is found for the Vega-type HD 123 356, with a dominance of small amorphous grains. We show that the infrared emission of the binary HD 123 356 is dominated by its late-type secondary, but optical spectroscopy is still required to confirm the age of the system and the spectral class of the companion. For most targets, this is their first mid-infrared spectroscopic observation. We investigate trends between stellar, disk, and silicate properties and confirm correlations identified in previous studies. Several objects present an exciting potential for follow-up high-resolution disk studies.

show abstract

“…Menard Young stellar objects are also variable at X-ray, ultraviolet, infrared, and radio wavelengths. Each of these wavelength regimes probes a di †erent aspect of the young star and its circumstellar material, and they can be used together to establish a more comprehensive picture of the temporal properties and physical characteristics of young stellar objects (see, e.g., Kenyon et al 1994 ;Guenther et al 2000 ;Yudin 2000). Near-infrared monitoring observations, the focus of this study, are expected to probe relatively cool phenomena compared with optical, ultraviolet, and X-ray studies and may probe phenomena not accessible to shorter wavelength studies, such as temperature, opacity, and geometry changes in the dust-and gas-rich circumstellar environment.…”

Section: Introductionmentioning

confidence: 99%

Near-Infrared Photometric Variability of Stars toward the Orion A Molecular Cloud

Carpenter

Hillenbrand

Skrutskie

2001

The Astronomical Journal

312

492

View full text Add to dashboard Cite

We present an analysis of J, H, and time-series photometry obtained with the southern 2MASS K s telescope over a region centered near the Trapezium region of the Orion Nebula cluster. These 0¡ .84 ] 6¡ data are used to establish the near-infrared variability properties of preÈmain-sequence stars in Orion on timescales of D1È36 days, D2 months, and D2 years. A total of 1235 near-infrared variable stars are identiÐed, D93% of which are likely associated with the Orion A molecular cloud. The variable stars exhibit a diversity of photometric behavior with time, including cyclic Ñuctuations with periods up to 15 days, aperiodic day-to-day Ñuctuations, eclipses, slow drifts in brightness over 1 month or longer, colorless variability (within the noise limits of the data), stars that become redder as they fade, and stars that become bluer as they fade. The mean peak-to-peak amplitudes of the photometric Ñuctuations are D0.2 mag in each band, and 77% of the variable stars have color variations less than 0.05 mag. The more extreme stars in our sample have amplitudes as large as D2 mag and change in color by as much as D1 mag. The typical timescale of the photometric Ñuctuations is less than a few days, indicating that nearinfrared variability results primarily from short-term processes. We examine rotational modulation of cool and hot starspots, variable obscuration from an inner circumstellar disk, and changes in the mass accretion rate and other physical properties in a circumstellar disk as possible physical origins of the near-infrared variability. Cool spots alone can explain the observed variability characteristics in D56%È 77% of the stars, while the properties of the photometric Ñuctuations are more consistent with hot spots or extinction changes in at least 23% of the stars, and with variations in the disk mass accretion rate or inner disk radius in D1% of our sample. However, di †erences between the details of the observations and the details of variability predicted by hot-spot, extinction, and accretion disk models suggest either that another variability mechanism not considered here may be operative or that the observed variability represents the net results of several of these phenomena. Analysis of the star-count data indicates that the Orion Nebula cluster is part of a larger area of enhanced stellar surface density that extends over a (3.4 pc ] 20 pc) region containing D2700 stars brighter than mag. 0¡ .4 ] 2¡ .4 K s \ 14

show abstract

Analysis of correlations between polarimetric and photometric characteristics of young stars

Cited by 38 publications

References 42 publications

Close binary companions of the HAeBe stars LkHα198, Elias 1, HK Ori and V380 Ori

Close binary companions of the HAeBe stars LkHα198, Elias 1, HK Ori and V380 Ori

Mid-IR observations of circumstellar disks

Near-Infrared Photometric Variability of Stars toward the Orion A Molecular Cloud

Contact Info

Product

Resources

About