TY - JOUR
T1 - K giants in 47 tucanae
T2 - Detection of a new class of variable stars
AU - Edmonds, Peter D.
AU - Gilliland, Ronald L.
N1 - Funding Information:
2Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Aeronautics and Space Administration.
Funding Information:
We acknowledge Abi Saha and Laura Fullton for kindly reading drafts of this Letter and the referee, Artie Hatzes, for reviewing the Letter. We also acknowledge useful discussions with Ata Sarajedini, Lawrence Cram, Andrea Dupree, and Tim Brown. This work was supported by NASA through grant GO-4664.01-92A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.
PY - 1996/6/20
Y1 - 1996/6/20
N2 - We report the discovery of variability among K giants in the globular cluster 47 Tucanae, using a time series of U exposures with the Hubble Space Telescope. The variables lie along a narrow band in the color-magnitude diagram, joining the faint end of the asymptotic giant branch to the red giant branch. The variations, if coherent, mostly have periods between ∼2 and ∼4 days, consistent with low-overtone radial pulsation or nonradial pulsation, and V amplitudes in the range 5-15 mmag, which explains their nondetection so far in clusters. One of the variables may have a period of 1.1 days and a V amplitude of 5.3 mmag. These stars define a new class of variable stars and probably contain variable field K giants such as α Boo as members. An understanding of their variations may have significant ramifications for theories of stellar structure and stellar evolution.
AB - We report the discovery of variability among K giants in the globular cluster 47 Tucanae, using a time series of U exposures with the Hubble Space Telescope. The variables lie along a narrow band in the color-magnitude diagram, joining the faint end of the asymptotic giant branch to the red giant branch. The variations, if coherent, mostly have periods between ∼2 and ∼4 days, consistent with low-overtone radial pulsation or nonradial pulsation, and V amplitudes in the range 5-15 mmag, which explains their nondetection so far in clusters. One of the variables may have a period of 1.1 days and a V amplitude of 5.3 mmag. These stars define a new class of variable stars and probably contain variable field K giants such as α Boo as members. An understanding of their variations may have significant ramifications for theories of stellar structure and stellar evolution.
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U2 - 10.1086/310108
DO - 10.1086/310108
M3 - Article
AN - SCOPUS:15444376418
SN - 0004-637X
VL - 464
SP - L157-L160
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2 PART II
ER -