Talk:CG4 Spring work

For Apr 14: KEVIN -- Reipurth and Pettersson 1993

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1993A%26A...267..439R&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf

Main Point

Found 8 new YSOs in Gum Nebula (near CG4 and Sa101 and CG13) using IR photometry, UBV photometry and spectroscopy.

High Level Summary

Surveyed 5 fields with 15 cometary globules Found 8 new YSOs Confirmed one previous YSO

Equipment Used

 Ha spectroscopy                      CTIO 60/90cm Curtis Schmidt telescope with 6deg prism    1-2hrs
 JHK IR photometry (sort of like us)  ESO 1m        J-H and H-K
 UBV photometry (like us)             ESO 1m
 Point source spectroscopy            ESO 1.52m and 3.6m        3700A to 7000A                    10-40 min

found there are different ages (spectra and movement away from globule) Found late-type premain sequence stars

Identified spectral type using spectra ruled out forground/background with spectra and

Most Interesting

Introduction: Good description of cometary nebulae Good rundown of CG formation theory

1.  OB starformed nearby and the UV radiation scrunched and eroded nearby nebula (some evidence in this paper for this method)
2.  or SN went off nearby and shockwave scrunched and eroded nearby nebula

CG4 might have been evaporating for 1,000,000years

CG4 might have been a shade for Sa101 to hide behind. Until the CG4 evaporation may have started >1,000,000 years ago. In faint background stars they found stars becoming more prominent as they used longer wavelength filters (good for us)

Spectral classes M3 to K7 M2, M3-4, K7-M0, K7, K2-5, K5, M1-2, K2

Not sure about this

Questions and Kevin trying to dodge the answers

TiO and MgH using the width and

Ha

width of line (spinning?)

Balmer series forbidden [OI] linesat 6300 and 6363A prominent absorption at 5577A absorbtion trough at 6200A deeper

I agree with this

found eight new YSOs in the area confirmed one previous YSO found there are different ages (spectra and movement away from globule) Found late-type premain sequence stars

I disagree with this

found there are different ages (spectra and movement away from globule) probably continuous (from 8 stars?)

Why we should care

found seven new YSOs in the area confirmed one previous YSO Used some of the same techniques we will Found YSOs and confirmed previous ones Found faint background stars getting more prominent in longer wavelength filters Not all CG had star formation but CG4 was one that had some nearby

For Apr 21: VIVIAN -- Kim et al 2003

http://adsabs.harvard.edu/abs/2003csss...12..799K Full Paper link click here. [1]

Main Point

High mass stars can terminate low mass star formation (LMSF) or they can trigger it.

High Level Summary

Pressure induced by winds and radiation from high mass stars and by radiation can sweep away low density clouds surrounding low mass stars, but can also collapse the surrounding clouds and start low mass star formation (LMSF) in the cores of these remnant clouds. Cometary globules in places like the Gum Nebula are perfect places to study this triggered LMSF. CGs are evaporating molecular cloud cores with head-tail geometry. The head points towards the HMS source of the winds and radiation causing the evaporation.

What they did

They analyzed X-Ray ROSAT/HRI data, Optical Data for photometry from CTIO/0.9m, and Near-IR using JHK images from the CIRIM detector on the CTIO/1.5m telescope.

Most Interesting

Section 3.2 addresses our CG4. They did optical photometry.

I disagree with this

Did they get different object data on different telescopes of the same or different regions. I'll explain better on the phone.

Why we should care

Summary states that "There are indeed candidate PMS stars in .... CG4 ..... They think there are a few PMS stars in CG4; that there are none around the eroded head of CG4 and suggest that there is an age gradient from the head to the tail. The suggested explanation is that the LMSF in the region may have been gradual and under the influence of the high mass stars in Vela OB2.

For Apr 28: CHELEN -- Kim 2005

http://adsabs.harvard.edu/abs/2005AJ....129.1564K

For May 5: CAROLYN -- Choudhury and Bhatt 2008

http://arxiv.org/PS_cache/arxiv/pdf/0811/0811.4389v1.pdf the ADS entry is http://adsabs.harvard.edu/abs/2009MNRAS.393..959C and I downloaded the real journal article for you (easier to read!) here: media:choud.pdf