Star Formation in Lynds Dark Nebulae. Ashley Peter, Willly Wassmer, Rose Haber. Abstract.
Ashley Peter, Willly Wassmer, Rose Haber
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.
Dust is found everywhere in the universe, dating back to nearly the beginning of time (Yan, 05).
Very cool stars (usually old)
Cool dust -
heated by hot stars
Black Hole accretion disks
Hot stars = young stars
Run of the mill stars
600 LY away
Infrared images of LDN 425 (left) and LDN 981 (right).
Greene, American Scientist, Jul-Aug 2001
Main accretion phase?
Late accretion phase?
Optically thick disk
Avg Mdisk~0.01 Msun
Optically thin disk
Avg Mdisk<~0.003 Msun
Class I (envelope) models
Class II (disk) models
Allen et al. 2004
Carballo, R et al. “Identification of IRAS Point Sources in Scorpio-Centaurus Lupus.”
184 sources from IRAS Point Sources Catalog
Classification- identify YSOs
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
Connelley, Michael et al. “Infrared Nebulae Around Young Stellar Objects.”
IRAS Point and Faint Source Catalogs
Class I YSOs
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
The purpose of this study is to obtain more data about known YSOs (young stellar objects) and find more candidate YSOs.
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.
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.