DUST IS FORMING ALONG THE RED GIANT BRANCH OF 47 Tuc

Journal Article · Tue Jul 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/718/1/522· OSTI ID:21455130

Origlia, Livia; Fusi Pecci, Flavio ^[1]; Rood, Robert T ^[2]; Fabbri, Sara; Ferraro, Francesco R; Dalessandro, Emanuele ^[3]

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1. INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
2. Astronomy Department, University of Virginia, Charlottesville, VA 22903 (United States)
3. Dip. di Astronomia, Universita degli Studi di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)

We present additional evidence that dust is really forming along the red giant branch (RGB) of 47 Tuc at luminosities ranging from above the horizontal branch to the RGB tip. The presence of dust had been inferred from an infrared excess in the (K - 8) color, with K measured from high spatial resolution ground-based near-IR photometry and '8' referring to Spitzer-Infrared Array Camera (IRAC) 8 {mu}m photometry. We show how (K - 8) is a far more sensitive diagnostic for detecting tiny circumstellar envelopes around warm giants than colors using only the Spitzer-IRAC bands, for example, the (3.6 - 8) color used by Boyer et al. In addition, we also show high-resolution Hubble Space Telescope Advanced Camera for Surveys I-band images of the giant stars that have (K - 8) color excess. These images clearly demonstrate that the Boyer et al. statement that our detections of color excess associated with stars below the RGB tip arise from blends and artifacts is simply not valid.

• OSTI ID: 21455130
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 718; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
COLOR
DUSTS
GIANT STARS
LUMINOSITY
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
PHYSICS
RESOLUTION
SPATIAL RESOLUTION
STARS
TELESCOPES