J/A+A/466/181 BVI photometry of Whiting 1 (Carraro+, 2007)
Whiting 1: the youngest globular cluster associated with the Sagittarius
dwarf spheroidal galaxy.
Carraro G., Zinn R., Moni Bidin C.
<Astron. Astrophys. 466, 181 (2007)>
=2007A&A...466..181C 2007A&A...466..181C
ADC_Keywords: Clusters, globular ; Photometry, CCD ; Photometry, UBVRI
Keywords: Galaxy: halo - Galaxy: evolution -
Galaxy: globular clusters: general -
Galaxy: globular clusters: Sgr dSph
Abstract:
Recently Carraro (2005ApJ...621L..61C 2005ApJ...621L..61C) drew attention to the
remarkable star cluster Whiting 1, showing that it lies at about 40kpc
from the Sun and is therefore unquestionably a member of the Galactic
halo (l=-60.6°). Its Color Magnitude Diagram (CMD) indicated that
Whiting 1 is very young (∼5Gyrs) for a globular cluster. It is highly
likely that Whiting 1 is originated in a dwarf galaxy that has since
been disrupted by the Milky Way. The main purpose of the present study
is to better constrain the properties of Whiting 1, and assess whether
it belongs to a stellar stream from the Sagittarius Dwarf Spheroidal
Galaxy (Sgr dSph). Deep CCD photometry in the BVI pass-band obtained
with the VLT is used to improve the quality of the CMD, and provide
more solid estimates of the cluster distance and age, while high
resolution spectra of three evolved stars obtained at Magellan is used
to derive the cluster kinematics and analyze its possible membership
to the Sgr dSph. We demonstrate that - independently on the Halo model
employed - Whiting 1 is part of the trailing stream of the Sgr dSph.
We derive a new age estimate of 6.5+1.0-0.5Gyr, and a smaller
heliocentric distance of 29.4+1.8-2.0kpc. The number of globular
clusters confirmed to be members of Sgr dSph is now 6. Among these
clusters, Whiting 1 is particularly interesting, being the youngest
and one of the most metal rich. The existence of Whiting 1 shows how
the Sgr dSph was able to form star clusters for a period at least of
6Gyr.
Objects:
--------------------------------------------------
RA (2000) DE Designation(s)
--------------------------------------------------
02 02 56.8 -03 15 10 Whiting 1 = WHI B0200-03
--------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 67 952 Photometry of Whiting 1
--------------------------------------------------------------------------------
See also:
J/A+A/450/105 : Properties of 153 Galactic globular clusters (Bica+, 2006)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq Sequential number
6- 13 F8.3 pix Xpos X position (1)
15- 22 F8.3 pix Ypos Y position (1)
24- 30 F7.4 mag Bmag B magnitude
32- 37 F6.4 mag e_Bmag rms uncertainty on Bmag
39- 45 F7.4 mag Vmag V magnitude
47- 52 F6.4 mag e_Vmag rms uncertainty on Vmag
54- 60 F7.4 mag Imag I magnitude
62- 67 F6.4 mag e_Imag rms uncertainty on Imag
--------------------------------------------------------------------------------
Note (1): Orientation is North up, East to the left. Scale is 0.2"/pix.
--------------------------------------------------------------------------------
Acknowledgements:
Giovanni Carraro, giovanni.carraro(at)unipd.it
(End) Giovanni Carraro [Padova, Italy], Patricia Vannier [CDS] 06-Mar-2007