Star Formation in Lynds Dark Nebulae

1. Star Formation in Lynds Dark Nebulae Ashley Peter, Willly Wassmer, Rose Haber

2. Abstract Dust is found everywhere in the universe, dating back to nearly the beginning of time (Yan, 05). Dust found in molecular clouds is crucial to the star formation process, as it allows gas to condense into pre-stellar cores and evolve into YSOs, or young stellar objects (Greene, 01). Research by Carballo (1992) identified new candidate YSOs in Scorpio-Centaurus Lupus, which was later confirmed by Connelley (2007), along with Padgett’s (2008) findings of over 300 YSOs in Ophuichus. In 1962, Beverly Lynds undertook a survey of dark nebulae and determined their locations and opacities (Lynds, 62). In this study, two small, isolated, dark molecular clouds, Lynds Dark Nebulae 425 and 981, which may contain areas of star formation and YSOs, were observed using the Spitzer Space Telescope in IRAC (3.6, 4.5, 5.8, and 8 microns) and MIPS (24 microns). The purpose was to obtain more data about known YSOs and find candidate YSOs. Using infrared images taken by Spitzer accessed through the Leopard software, mosaics were made using MOPEX, and candidates were found through certain criteria. Fluxes were calculated using APT, were converted to magnitudes using a generated Excel spreadsheet, and SEDs (Spectral Energy Distributions) and color-color plots were constructed and compared to those of YSOs.

3. Need Dust is found everywhere in the universe, dating back to nearly the beginning of time (Yan, 05). http://www.iras.ucalgary.ca/~volk/figs/disk2.jpg

4. Knowledge Base Why infrared?Galaxies at Many Wavelengths: Near IR 2MASS, Spitzer Visible HST X-ray Chandra UV GALEX,HST Far IR Spitzer 1600nm 1800K Very cool stars (usually old) 100,000nm 29K Cool dust - heated by hot stars 2 nm 1.5x106K Black Hole accretion disks 200nm 14,500K Hot stars = young stars 500nm 5800K Run of the mill stars (all ages)

5. Spitzer Telescope (October 2000) (IRAC) (MIPS)

6. Lynds 1014 IR Visible 600 LY away

7. Lynds 425 and 981 Infrared images of LDN 425 (left) and LDN 981 (right).

8. Formation of a low mass star Class 0 Class I Class II Class III Greene, American Scientist, Jul-Aug 2001

9. Class 0 Main accretion phase? Menv>~0.5 Msun <~104 years Class I Late accretion phase? Menv<~0.1 Msun ~105 years Class II Optically thick disk Avg Mdisk~0.01 Msun ~106 years Class III Optically thin disk Avg Mdisk<~0.003 Msun ~107 years

10. IRAC Color-Color Diagrams Class I (envelope) models Av=30 Class II (disk) models Allen et al. 2004

11. Carballo, R et al. “Identification of IRAS Point Sources in Scorpio-Centaurus Lupus.” Literature Review 184 sources from IRAS Point Sources Catalog Photometry Classification- identify YSOs

12. Rebull, L.M. et al. “Spitzer Observations of Young Stars in the Witch Head Nebula (IC 2118).” Spitzer/IRAC and MIPS observations- March 05/06 Photometry, mosaics created- MOPEX SEDs and color-color plots

13. Connelley, Michael et al. “Infrared Nebulae Around Young Stellar Objects.” IRAS Point and Faint Source Catalogs Class I YSOs SEDs

14. Padgett, D et al. “The Spitzer C2D Survey of Large, Nearby, Interstellar Clouds: VII. Ophiuchus Observed with MIPS.” MIPS observations of Ophiuchus- 14.4 square degrees Flux densities converted to magnitude BCD’s mosaicked- MOPEX Color-color and color-magnitude diagrams

15. Purpose The purpose of this study is to obtain more data about known YSOs (young stellar objects) and find more candidate YSOs.

16. Hypotheses • H(o)- LDN 425 and LDN 981 are areas of young star formation • H(a)- star formations do occur in LDN 425 and 981, YSOs will be found

17. Methodology Obtained images from the Spitzer Space Telescope on Lynds Dark Nebulae 425 and 981 (Leopard) Mosaics of LDN 981 made (MOPEX) Mosaics of LDN 425 made (MOPEX) Searched for candidates within clouds using criteria such as infrared excess Fluxes of candidates calculated using APT (Aperture Photometry Tool) Using Excel the fluxes were converted into magnitudes Using these values SEDs (spectral energy distributions) and Color-Color plots were made to compare the YSO candidates to known YSOs.

18. Bibliography Carballo, R et al. “Identification of IRAS Point Sources in Scorpio-Centaurus Lupus.” Astronomy & Astrophysics. 1 April 1992. Pages 106-124. Connelley, Michael et al. “Infrared Nebulae Around Young Stellar Objects.” The Astrophysical Journal. 20 November 2006. DeWolf, Chris et al. “Star Formation in Lynds Dark Nebulae.” 2008. Greene. “Star Formation.” American Scientist, July-August 2001. Kun, M. “Star Formation in L1199.” Kluwer Academic Publishers. 1995. Lynds, Beverly T. “Catalogue of Dark Nebulae.” American Astronomical Society. NASA Astrophyiscs Data System. 29 January 1962. Padgett, D et al. “The Spitzer C2D Survey of Large, Nearby, Interstellar Clouds: VII. Ophiuchus Observed with MIPS.” The Astrophysical Journal. 21 September 2007. Quanz, S.P. “Dust Rings and Filaments Around the Isolated Young Star V1331 Cygni.” The Astrophysical Journal. 26 October 2006. Pages 1-15. Rebull, Luisa M. “Studying Young Stars.” 20 November 2007. <https://coolwiki.ipac.caltech.edu/index.php/Studying_Young_Stars> Rebull, Luisa M. et al. “Spitzer Observations of Young Stars in the Witch Head Nebula (IC 2118).” 2007 AAS/AAPT Joint Meeting, Bulletin of the American Astronomical Society, Vol. 38, p. 1053. December 2006. Rho, J. et al. “Freshly Formed Dust in the Cassiopeia A Supernova Remnant as Revealed by the Spitzer Space Telescope.” Astrophysical Journal. 18 September 2007. Sartori, M. “The Star Formation Scenario in the Galactic Range from Ophiuchus to Chamaeleon.” Instituto Astronômico e Geofísico. July 2000. Wilking, B.A. “Star Formation in the Ophiuchus Molecular Cloud Complex .” The Astrophysical Journal. Page 159. 1992. Yan, Lin et al. “Spitzer Detection of PAG and Silicate Dust Features in the Mid-Infrared Spectra of z 2 Ultraluminous Infrared Galaxies.” The Astrophysical Journal. 14 April 2005. Pages 1-22.