J/AJ/154/72 Coordinates and photometry of stars in Haffner 16 (Davidge, 2017)
Haffner 16 redux: revisiting a young cluster in the outer galaxy.
Davidge T.J.
<Astron. J., 154, 72-72 (2017)>
=2017AJ....154...72D 2017AJ....154...72D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, SDSS
Keywords: open clusters and associations: individual: Haffner 16
Abstract:
Images and spectra recorded with the Gemini Multi-Object Spectrograph
on Gemini South are used to investigate the stellar content of the
open cluster Haffner 16. The (i',g'-i') color-magnitude diagram (CMD)
constructed from these data extends over 10mag in i', sampling the
cluster main sequence (MS) and 5mag of the pre-MS (PMS). The fraction
of unresolved equal mass binaries among PMS stars is estimated to be
0.6±0.1. The isochrones do not track the PMS on the CMD, in the
sense that the PMS has a shallower slope on the CMD than predicted by
the models. Still, a dip in star counts, which is associated with the
relaxation of PMS stars onto the MS, is identified near i'=17. The
depth and brightness of this feature-as well as the morphology of the
cluster MS on the CMD-are matched by models with a slightly sub-solar
metallicity that have an age of ∼20Myr and a distance modulus of
12.3±0.2. A light profile of Haffner 16 is constructed in the W1
filter (λcen=3.4µm), which suggests that the cluster is
surrounded by a diffuse stellar halo. Spectra of candidate cluster MS
and PMS stars selected according to location on the CMD are presented.
The spectra show characteristics that are suggestive of a sub-solar
metallicity. Hα emission is common among objects on the PMS
locus on the CMD near i'=18. It is suggested that the location of the
Haffner 16 PMS on the CMD is affected by large-scale cool spot
activity, likely induced by rapid stellar rotation.
Description:
The images and spectra that are the basis of this study were recorded
with Gemini Multi-Object Spectrograph (GMOS) on Gemini South as part
of program GS-2014A-Q-84 (PI: Davidge). GMOS is the facility
visible-light imager and spectrograph. The detector was (the CCDs that
make up the GMOS detector have since been replaced) a mosaic of three
2048*4068 EEV CCDs. Each 13.5µm square pixel subtended 0.073arcsec
on the sky. The three CCDs covered an area that is larger than that
illuminated by the sky so that spectra could be dispersed outside of
the sky field. The images and spectra were both recorded with 2*2
pixel binning.
The g' (FWHM=0.55) and i' (FWHM=0.45) images of Haffner 16 were
recorded on the night of 2013 December 31.
The GMOS spectra were recorded during five nights in 2014 March (Mar
19, Mar 27, and Mar 30) and April (Apr 2, and Apr 3). The spectra were
dispersed with the R400 grating (λblaze=7640Å,
400lines/mm).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 67 117 Spectroscopic targets
--------------------------------------------------------------------------------
See also:
III/232 : STELIB: A library of stellar spectra at R∼2000 (Le Borgne+, 2003)
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Star Star identification number (1)
5 A1 --- f_Star [ab*] Flag on Star (*=star that have multiple
observations; a and b=stars that are in the
same slitlet)
7- 15 A9 --- OStar Star identification number in other mask(s) (1)
17- 26 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
28- 37 F10.6 deg DEdeg Declination in decimal degrees (J2000)
39- 45 F7.2 pix Xpix [938.8/2619.7] X pixel coordinate (2)
47- 53 F7.2 pix Ypix [195.7/2211] Y pixel coordinate (2)
55- 60 F6.3 mag i'mag [13.65/19.78]? The i' band magnitude
62- 67 F6.3 mag g'-i' [-0.26/2.61]? The (g'-i') color index
--------------------------------------------------------------------------------
Note (1): The identification number for each target consists of the mask number
(1-6), followed by the slit number, defined such that slitlet number 1 for
each mask is the closest to the bottom of the science field.
Note (2): On the Gemini Multi-Object Spectrograph (GMOS) detector. Each
13.5µm square pixel subtended 0.073 arcsec on the sky.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 09-Nov-2017