POLARIMETRY OF DG TAU AT 350 mum

Journal Article · Sun Nov 01 04:00:00 EST 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/705/1/717· OSTI ID:21378360

Krejny, M; Matthews, T G; Novak, G ^[1]; Cho, J ^[2]; Li, H ^[3]; Shinnaga, H ^[4]

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1. Department of Physics and Astronomy, Northwestern University, 2131 Tech Dr., Evanston, IL 60628 (United States)
2. Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)
3. Harvard Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
4. Caltech Submillimeter Observatory, 111 Nowelo St., Hilo, HI 96720 (United States)

We present the first 350 mum polarization measurement for the disk of the T Tauri star (TTS) DG Tau. The data were obtained using the SHARP polarimeter at the Caltech Submillimeter Observatory. We measured normalized Stokes parameters q= -0.0086 +- 0.0060 and u = -0.0012 +- 0.0061, which gives a 2sigma upper limit for the percent polarization of 1.7%. We obtain information about the polarization spectrum by comparing our 350 mum measurement with an 850 mum polarization detection previously published for this source. Comparing the two measurements in Stokes space (not in percent polarization) shows that the two data points are not consistent, i.e., either the degree of polarization or the angle of polarization (or both) must change significantly as one moves from 850 mum to 350 mum. This conclusion concerning the polarization spectrum disagrees with the predictions of a recent model for TTS disk polarization. We show that this discrepancy can be explained by optical depth effects. Specifically, we demonstrate that if one were to add more mass to the model disk, one would expect to obtain a model polarization spectrum in which the polarization degree falls sharply with increasing frequency, consistent with the observations at the two wavelengths. We suggest that multiwavelength polarimetry of TTS disk emission may provide a promising method for probing the opacity of TTS disks.

• OSTI ID: 21378360
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 705; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
ERUPTIVE VARIABLE STARS
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
POLARIMETERS
POLARIMETRY
POLARIZATION
PROTOPLANETS
SPECTRA
STARS
STOKES PARAMETERS
T TAURI STARS
VARIABLE STARS
WAVELENGTHS