Lynds Target Selection

I haven't done this legwork yet because I thought you might want to be involved - finding a good target for observation is a substantial part of doing science! :)

Ideally, we'd pick a target for our observation using a combination of

• searching ADS and/or SIMBAD for existing literature .... we want something that doesn't have a LOT of other references, but some references are fine - if someone else has already assembled data on an object, we might be able to use those data and/or results - we just don't want something that has already been "done to death." (page from the wiki on literature searching)
• checking POSS and other existing multi-wavelength data to see what the object looks like in those bands .... does it look thick and dark in the optical? bright in the infrared? Both of those things suggest that it will be interesting with Spitzer. Something that looks diaphanous in the optical will likely turn out to be completely transparent with Spitzer. (page from the wiki on introduction to data at other wavelengths; you can also do this with Leopard -- see next item.)
• and, checking to see if it is or is not in the Spitzer archive .... you need to use Leopard to do this. (page from the wiki on searching the archive using Leopard-- NB: "searching the archive to see what is there" is the same thing as "downloading data" except that when you search to see what is there, you don't actually download the data, you just see that there is something there.) Also, note that just because there is data already in the Archive on a given cloud doesn't mean it's a BAD thing, just that it's not a good thing for a new proposal. You should make a note of the "nice" ones you find, because you can go grab the data as soon as the data are public.

My original thoughts on good targets were the following three:

• LDN 470
• LDN 1225
• LDN 880 (but maybe too diaphanous)

And, at the AAS, you guys also came up with

• LDN 1340

The master list of objects that I worked from is here, courtesy of Babar Ali. Note that these are all opacity class 5 objects. Opacity class 5 or higher is what we probably want for Spitzer observations. None of these have many references in ADS. This is not meant to be a comprehensive list by any means, just a place to start. If you want to instead start with the complete Lynds Dark Nebulae catalog, it's here (the data are linked as "online data" or something similar).

Please post your thoughts and reactions to each of these targets, and any new ones you think are viable candidates for observation. For example, you might post a gif or jpeg of the POSS image you found, or a summary list of references (e.g., "3 papers besides Lynds, one radio, others submm" or whatever). Note the syntax I'm using to post comments on LDN 1340 below -- this is a method suggested by the Oil City folks, and I think it works really well to follow the conversation. See the help page linked from the left (above the search box) for hints on how do this.

LDN 880

--Guastella 20:48, 8 January 2008 (PST) Here is the article I mentioned in our meeting earlier today.

THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 123:233È250, 1999 July (1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. A CATALOG OF OPTICALLY SELECTED CORES CHANG WON LEE AND PHILIP C. MYERS [...] This didn't format well. Please let me know if there is a better way to send papers Thanks Pete

(--Rebull 09:25, 9 January 2008 (PST) he's right, this didn't format well, so I replaced it with a link directly to ADS, from which you can get the complete article - there's no access restrictions on it, and if you go there, you can get the originally formatted PDF or the html. ADS link to the Lee and Myers paper

LDN 1340

--Rebull 20:14, 8 January 2008 (PST) Here's a summary of the latest developments on this object:

One of you (Peter?) suggested this object - and it was a fabulous suggestion. Beautiful in the optical, with IRAS sources, a handful of existing literature, and no Spitzer. Perfect! The icing on the cake was that it's visible in the Spring.

One of you (Peter again?) noticed that there was another AAS poster from 2005 on this object. I mentioned that I knew 2 of the authors (JoAnn O'Linger and Grace Wolf-Chase). Not 2 hours after leaving you, I ran into them. One thing I didn't mention in the context of searching the archive is that there is an open call for proposals out now, eg., there are ~700 proposals for objects that are currently being reviewed, and 20% of them will get their targets approved by March. To some extent, since you're putting in a proposal more or less now, you kind of trump them. On the other hand, it's never good to make enemies.... So, it turns out that JoAnn and collaborators have submitted a proposal to map this region over 1 square degree. There's no guarantee that their data will actually be taken this cycle (before we run out of cryogen in Spring 2009), but at the same time, we probably won't be able to ask for a full square degree (it would take too much time). We could pick a subregion to focus on, or we could find another target entirely.

I'll continue to talk to JoAnn (we had just a brief conversation today), and if I can get her posters (one from before, one from this meeting!), I'll post them here.

[END]

In case we are still looking at this here is the 2005 Abstract Submillimetre Observations of an Intermediate-Mass Star Forming Cloud Core J. O’Linger1, G. H. Moriarty- Schieven2, and G. A. Wolf-Chase3,4, 1Spitzer Science Center (joanno@ipac.caltech.edu), 2National Research Council of Canada, JAC (g.schieven@jach.hawaii.edu), 3Adler Planetarium & Astron. Mus. (gwolfchase@ adlerplanetarium.org), 4Univ. of Chicago (grace@horta.uchicago.edu). We present preliminary results in an ongoing, comprehensive investigation of the star formation activity in LDN 1340. This dark nebula (opacity class 5) is located approximately 600 pc away, in the constellation Cassiopeia. Due to various reflection nebulae and a significant number of embedded IRAS sources, it was identified as a region of active star formation by Kun et al., 1994 [1]. Star formation occurs when the parent molecular cloud collapses to form young stars of different masses. A number of investigators have studied various mechanisms, which might trigger and/or accelerate this collapse and fragmentation process [2]. Clearly, the ionization fronts and stellar winds associated with massive stars have a significant impact on their natal environments, as do the shock waves from the supernovae at the ends of their brief lifetimes. These effects may induce subsequent generations of star formation, but if the turbulence created within the ambient cloud is sufficiently disruptive, it may actually disperse the cloud, causing star formation to cease [3]. To date, studies of triggered star formation have tended to concentrate on the most massive of stars (i.e., O and early B-types) and the star-forming regions in their immediate vicinities; the question of whether or not intermediate- mass stars (such as late B and early A-types) are capable of causing similar triggering events has not been thoroughly examined. Submillimeter maps, at 450 and 850 microns, of a portion of the L1340 cloud (L1340B) were obtained with the SCUBA bolometer array on the James Clerk Maxwell Telescope located on Mauna Kea, Hawaii. The image is presented in Figure 1. We have observed more than two dozen submillimeter sources in a ~17’ by 12’ region, most of them undetected at any other wavelength. A few of them are associated with previously identified IRAS or 2MASS sources. We have also mapped the region in the emission from the J=3-2 transition of CO. As can be seen in Figure 1, most of our detected sub-mm sources are located in ridges, like “pearls in a string”, which surround voids. Also shown in this figure are known low- and intermediate-mass stars. Morphology and classifications of these objects suggest that we are witnessing triggered star formation. For example, we discuss the case of the Herbig Be star known as “R3” in the paper by Kun et al. [1]. In Figure 1, the sources closest to R3 are T Tauri stars (class II) candidates (determined from 2MASS database using the classification scheme of Lee et al. [3], while beyond those objects lies a ridge containing only submillimeter sources and Class I candidates. Assuming that the ridge represents the location of the ionization front from R3, calculations to estimate the timescale involved (using as the propagation velocity the sound speed from Lee et al. [3], i.e. 10 km/s), show that the time it would take for the ionization front to reach the five nearest T Tauri candidates would be of order 2.3Ma (TT3) to ~11Ma (TT1). In this poster, we will discuss the evidence for triggered star formation within this cloud, based on dust continuum, CO, 2MASS and other data. References: 1. Kun, M., et al. 1994, A&A, 292, 249 2. Elmegreen, B. 1998, Observations and Theory of Dynamical Triggers for Star Formation, ed. C.E. Woodward, J.M. Shull, & H.A. Thronson, ORIGINS, ASP Conference Series 148 3. Lee, H., Chen, W., Zhang, Z., & Hu, J. 2005, Triggered Star Formation in the Orion Bright-Rimmed Clouds, arXiv:astro-ph/0502061 v1 Protostars and Planets V 2005 8600.pdf Figure 1: 850 μm image of theL1340B intermediate-mass star forming region. The field shown is approximately 17’x11’ in extent. Known A and B stars are indicated (see legend above), as well as candidate T Tauri stars and previously unidentified scuba sources. Protostars and Planets V 2005 8600.pdf