CG4 Proposal
Background information
Identifiers (aliases) for CG 4 ... BHR 21, Sandqvist 103, FEST 2-30, DCld 259.4-12.7
I found this by typing CG4 into SIMBAD. The results were in the middle of the page. Scrolling down further, there's a list of 20 articles in which CG 4 is mentioned.
Talk to you on Wednesday! --chj
My Plan to continue Lit. search--Mallory 23:35, 11 January 2010 (PST) is to finish SIMBAD, then go to ADS and to find a way to confirm and quantify lots! of IR (probably by opacity class) and little UV/max not to exceed a threshold to be determined; don't want the object to be a middle-aged star already.
Is it the group's intention to consider locations outside of CG4, which could be cluster members?
--Mallory 23:28, 11 January 2010 (PST)Carolyn
In a search through SIMBAD for CG 4 info, some interesting info and unanswered questions have emerged.
If a gaseous region were collapsing due to a radiation-driven implosion, what's to stop it from rebounding back out, and how would we know the mechanism had occurred? Maybe by the length of tails (also created by outward pressures)? Is this a safe assumption? There seems to be a conflict between different analyses as to whether tails can be traced by CO(12) spectra. How to resolve? If collapse/expansion, and rotation can occur all in the same region, are there any tools other than redshift to sort out what is happening? Interesting that there could be more than one "Center of Influence' in a region, i.e. massive star,--Mallory 15:48, 12 January 2010 (PST) whose radiation influences the CG's evolution.
chj, I'm not closely enough focused? Your ideas and suggestions?
I'll continue info-gathering. You know, this is grinding but fun; it's interesting, and I'm figuring that the Laws of Physics are the same throughout the Universe. -C
here is the paper from serena from 2005
http://adsabs.harvard.edu/abs/2005AJ....129.1564K
--Rebull 15:57, 13 January 2010 (PST)
Title: Low-Mass Star Formation in the Gum Nebula: The CG 30/31/38 Complex Authors: Kim, Jinyoung Serena; Walter, Frederick M.; Wolk, Scott J. Affiliation: AA(Department of Physics and Astronomy, State University of New York at Stony Brook, NY 11794-3800 serena@as.arizona.edu.; Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065.; Visiting Astronomer, Cerro Tololo Inter-American Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under contact with the National Science Foundation.), AB(Department of Physics and Astronomy, State University of New York at Stony Brook, NY 11794-3800 serena@as.arizona.edu.), AC(Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138.) Publication: The Astronomical Journal, Volume 129, Issue 3, pp. 1564-1579. (AJ Homepage) Publication Date:03/2005 Origin:UCP AJ Keywords:Stars: Circumstellar Matter, ISM: H II Regions, ISM: Globules, Stars: Formation, Stars: Low-Mass, Brown Dwarfs, Stars: Pre-Main-Sequence DOI:10.1086/428002 Bibliographic Code:2005AJ....129.1564K
Abstract We present photometric and spectroscopic results for the low-mass pre-main-sequence (PMS) stars with spectral types K-M in the cometary globule (CG) 30/31/38 complex. We obtained multiobject high-resolution spectra for the targets selected as possible PMS stars from multiwavelength photometry. We identified 11 PMS stars brighter than V=16.5 with ages <~5 Myr at a distance of approximately 200 pc. The spatial distribution of the PMS stars, CG clouds, and ionizing sources (O stars and supernova remnants) suggests a possible triggered origin of the star formation in this region. We confirm the youth of the photometrically selected PMS stars using the lithium abundances. The radial velocities of the low-mass PMS stars are consistent with those of the cometary globules. Most of the PMS stars show weak Hα emission with Wλ(Hα)<10 Å. Only one out of the 11 PMS stars shows a moderate near-IR excess, which suggests a short survival time (t<5 Myr) of circumstellar disks in this star-forming environment. In addition, we find five young late-type stars and one Ae star that have no obvious relation to the CG 30/31/38 complex. We also discuss a possible scenario of the star formation history in the CG 30/31/38 region.
http://adsabs.harvard.edu/abs/2006AAS...20921915K
Title: Star Formation in the Gum Nebula: Cometary Globules CG4/6/SA101
Authors: Kim, Jinyoung S.; Walter, F. M.; Wolk, S. J.; Sherry, W. H.; Foster, M.
Affiliation: AA(Univ. of Arizona), AB(Stony Brook University), AC(CfA), AD(NSO/NOAO), AE(Univ. of Arizona)
Publication: 2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #219.15; Bulletin of the American Astronomical Society, Vol. 38, p.1205
Publication Date: 12/2006
Origin: AAS
Bibliographic Code: 2006AAS...20921915K
Abstract As a part of our on-going program to study star formation under various environments, we present preliminary results from our multi-wavelength study of a bright-rimmed cometary globule complex, CG4/6/SA101 in the Gum Nebula. These cometary clouds are photo-evaporating due to UV radiation from neighboring O stars (10 < d < 100 pc) in the Vela OB2 association. The intermediate and low-mass stars in these cometary clouds form in an environment that differs from both the quiet isolation of young stars in T-associations such as Taurus and the violently energetic environment like that of the Orion Nebula cluster (ONC). The moderate separation between the cometary clouds and the O stars creates a radiation environment that has an intensity intermediate between the Taurus and Orion star forming regions. Circumstellar material and accretion disks may last longer than those in ONC, yet may not survive as long as they would in an isolated region such as Taurus or TW Hya. We compare our results with other star forming regions under different environments.
http://adsabs.harvard.edu/abs/2005sptz.prop20714K
Title: Probing environment and circumstellar disk evolution in triggered star forming regions: IRAC and MIPS imaging of bright-rimmed globules CG4/SA101 and CG30/31 Authors: Kim, Jinyoung Serena; Sherry, Wiiliam Publication: Spitzer Proposal ID #20714 Publication Date: 06/2005 Origin: SPITZER Bibliographic Code: 2005sptz.prop20714K
Abstract We propose to obtain IRAC and MIPS images of a newly discovered star forming region, cometary cloud complex CG~4/SA101 (Kim et al. 2005c). We also propose to acquire more complete IRAC and MIPS images of a cometary globule complex CG~30/31, where we found young stars (Kim et al. 2005a,c), but existing program by a Spitzer legacy team (c2d) did not observe. Both star forming complexes reside in the Gum Nebula, where early O stars, Wolf-Rayet star, supernovae remnants, and OB associations produce strong ionizing UV photons. These two star forming regions are in a photoevaporating cometary shaped bright-rimmed clouds, at few tens of parsecs away from the common center of main ionizing sources in the Gum Nebula, placing them in a 'intermediate' UV radiation field between Orion-like Strong radiation field regions and Taurus-like weak radiation field regions. We propose to perform comparative and statistical studies probing circumstellar disk characteristics and evolution in different star forming environments together with existing data of well-known star forming regions. The age range of the young stars in these regions (1-5 Myr old) is also of a great interest, because this is a time when transition from optically thick disks to optically thin debris disks occurs. Therefore, this proposed observations will provide an important dataset to study lifetime of inner disks and optically thick disk evolution in such environments. We probe yet another common mode of star formation, forming in groups in triggered mode or influenced by UV photons from nearby ionizing sources. Our dataset and study will contribute to a better understanding of star formation and circumstellar disk evolution linking well-known star forming regions in weak and strong radiation field environments. We believe that this dataset will also benefit other star formation and disk communities for various other studies in addition to existing dataset of clusters and associations, obtained by GTO, legacy, and GO1.
Existing observations
Wiki page on searching Leopard is part of How do I download data from the Spitzer Telescope?
Education
Viv's assignment in the group was to organize the Education portion of our proposal. What if we make a case for the importance of:
- Teacher/Student/Scientist Scientific Research within the context of today's national and education initiatives.
- NITARP as a Professional Learning Community offering a Center of Strength in Science Teacher Leadership
- Include the variety of expected student populations and levels of participation, considering how we might measure impact across these groups.
I like these three strands. Great idea, Viv.
--chj 17:19 CST 13-Jan-2010.
test. CRM--Mallory 21:02, 13 January 2010 (PST)
The following is a summary of info describing the CG4 environment, and includes a small amount of info from other areas quantitatively similar to the Gum Nebula area. The environmental characteristics listed will describe the environment needed for star formation, demonstrated by the presence of YSOs in the--Mallory 22:24, 13 January 2010 (PST) region:
-cg4 resides in the Gum Nebula, within the constellation Puppis, adjacent to Vela. This area is 1,300 LY distant, and even visually is laced with plentiful clouds of gas and dust.
-using appropriate wavelengths, should do a search for nearby massive O & B stars (typical neighborhood bullies)to determine the possibility of photoevaporation of coalescing dust and gas taking place in newly formed stars, and if so, switch area being investigated. Cometary Globule tails all coinciding in direction they're pointing is another indication that newly forming stars are being photoevaporated by nearby large star radiation/emissions. There can be a number of Centers of Influence near a newly forming Star Cluster, check this optically, in radio, and in both UV and Xray.
-Note that radiation driven implosion also occurs. Do muiltiwavelength study. Radio wavelengths especially.
-Expect IR excess in area of star formation (Universal Gas Law; volume decrease/temp increase) Necessary to have an average value for IR around a small mass Main Sequence star, so we know what amount 'excess IR' is.
- If head of cometary nebula is opaque, it can be assumed that sufficient gas and dust exist to create new stars. Thus, this opacity/Opacity Class is an indicator of star-forming region BUT needs to be quantified and observed in the appropriate wavelengths/optical photometry/MIPS probably.
- Information about contraction/expansion/rotation, can be obtained from red-blue shift observations. This is necessary information! Personal question; could implosion produce an outward rebound?
-Spectroscopic info can reveal the age/stage of development of baby stars uncovered in this study. MIPS.
-To determine which stars visible in same area are members of the same CG4 Cluster, see common age/convection % compared to radiation & conduction, speed of rotation (need to know axis of rotation to determine blue-red shift anyway), variability, spatial location, and spatial motion of all the local stars/i.e. do they seem to be moving as a group/cluster.
-Excess IR (define 'excess' as variation from average IR emission from a similar mass young Main Sequence star IR average emissions) typifies newly forming stars, such as what we are looking for in CG4. Conflict in literature about UV emissions; forming star should have almost none/core processes do not yet produce, but very young stars can have a lot of UV emission due to repid rotation. Supposedly, really young stars have low Magnetic Field.
-Another variable of which to be aware, is the number of YSOs in a given area. Too many, and only those with largest relative mass will grow to be stars, since they have the gravitational-strength advantage/capture the most infalling gas+dust. (Think nestfull of eagle eggs, which hatch at different times.)
The sources listed below indicate that these are the qualities in nebulae which affect Star Formation.
Carolyn Mallory
Sources Used to Gather This information Include but are Not Limited to:
SIMBAD, ic 2118, ADS, CoolWiki Finding Cluster Members, Spitzer Archives, Infrared Handbook by Wolfe & Zissie.
