Studies of Resolved Objects in M31
July 24, 2009, rev 2
This page contains a description of an on-going study of star
clusters,
HII regions, PNe and individual stars in M31 done with Hectospec on the
MMT by
Nelson Caldwell and a host of others1. The first paper
of the project has
been published:
Star Clusters in M31: I. A
Catalog and a Study of the Young Clusters
(AJ, 2009, 137, 94).
At this web site, you will find the new M31
cluster catalog and links to the
ground based and HST images of stars and clusters. Also appearing
are the spectra of
the young clusters and individual stars . Spectra and velocities of the old clusters
will be released upon acceptance of that
paper.
Ideally, this site would be a WIKI site, but currently the CfA doesn't
allow such sites. If anyone else has ideas about how and where to
create such a site, I'd be
delighted to help out with that.
Regards,
caldwell here at cfa.harvard.edu
1Including but not limited to : Heather Morrison, Paul
Harding, Jim Rose, Ricardo Schiavon, Genevieve Graves, Jeff Kreissler,
Jay Strader.
Images of Clusters and Stars in the
revised Hectospec M31 catalog
Spectra and Images of just Star Clusters in M31
Images of Old Star Clusters in
M31, ordered by estimated mass
Spectra and Images of Young Star Clusters
in M31, ordered by estimated mass
Spectra and Images of Young Star Clusters
in M31, ordered by estimated age
Images and Spectra of Stars in the M31
catalog
Spectra
Spectra of the young clusters and the stars are now available at the
links above. These are in jpg
format currently. Click on the postage stamp for full resolution.
The spectra (aside of a few problem cases that are obvious - young
clusters with red continua)
have been flux calibrated, deredshifted (actually deblueshifted)
and dereddened.
These plots show only the blue part of the spectrum. The data was
smoothed before plotting. At
a later time I will make the actual spectra available. Spectra do exist for
most of the old clusters, but won't be released till that paper is published.
Postage stamp images of selected
Objects in M31
These images come from three sources: the digitized Palomar survey, the
Local Group Survey of Massey et al. 2006, AJ, 131, 2478, and HST (ACS
or WFPC2). For each object in these lists,
the following are shown:
- the location in M31 (except for more distant objects - my image
doesn't cover enough area).
- an HST image if possible, either from ACS or WFPC, typically in
bands redder than F300W. The field size is 10 arcsecs.
- the V and I images taken with the Mayall 4m telescope as
presented in the LGS, if available. Field is 30 arcsec.
- the Palomar Schmidt image, for cases where there is no LGS image.
Field is 2 arcmin.
The HST images are not complete, and in some cases what is shown is
merely one image out of a sequence, because the HST archive hasn't yet
combined those images. Those will contain annoying cosmic ray
hits. Each web page contains a list of objects to the left,
ordered as stated. The images will appear to the right after clicking.
The names used are those from the RBC, and basic information appears
next to the images (type, velocity, V magnitude, comments).
"Type" is explained in the catalog notes (see link below).
The WCS on the HST images is not always good, so sometimes the target
will be offcenter in the HST images. The images all have N at the top,
East to the left (which isn't true for the images in the paper - oops!).
I have made great use of these images to clean up the cluster catalog,
but that job is not complete - every day or so I change an object's
classification from cluster to star or vice-versa. If anyone else
takes the time to look through these and notes a discrepant type,
please feel free to advise me so that I can make changes to the catalog.
Note that objects with an "x" suffix were initially thought to be the
object (usually the real object is a few arcsecs away and more
difficult to see), and were observed with Hectospec before the mistake
was realized. These are nearly all stars.
AAS machine format for the catalog
I don't actually use this format myself, preferring starbase format
(tab delimited), but anyway, here is the entire Hectospec catalog,
ordered by RA, and containing the updated coordinates, V
magnitudes where extant, a rough type classification, and some notes as
described in the table and the paper. This catalog includes more
objects than are in the catalog
paper, and is believed to incorporate all the Revised Bologna
catalog (Galleti et al. 2007, A&A, 471, 127) entries except
for a handful of the clusters found on HST images and
reported in the papers of Hodge and collaborators. Eventually those
will appear here as well. Several hundred entries labeled
"bstar", "astar", "fstar", or "ysg" (yellow supergiant) are also
included, and can safely be ignored for the time being. The type
classification comes mostly from the spectra, though for a few cases
where I don't have spectra but the images (or previous detailed work)
indicate an old cluster, I say that.
This version is more up-to-date than the
published version contained in the aforementioned paper.
M31 Hectospec catalog