Star Formation in Lynds Dark Nebulae
Transcript Star Formation in Lynds Dark Nebulae
Star Formation in Lynds Dark
Ashley Peter, Willly Wassmer,
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
back to nearly the
beginning of time
Galaxies at Many Wavelengths:
Hot stars =
accretion disks young stars
Run of the
Very cool stars Cool dust (usually old)
heated by hot
600 LY away
Lynds 425 and 981
Infrared images of LDN 425 (left) and
LDN 981 (right).
Formation of a low mass star
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
IRAC Color-Color Diagrams
Class I (envelope)
Class II (disk) models
Allen et al. 2004
Carballo, R et al. “Identification of IRAS Point Sources in
184 sources from IRAS Point
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
SEDs and color-color
Connelley, Michael et al. “Infrared Nebulae Around Young Stellar Objects.”
IRAS Point and Faint Source
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
Flux densities converted
BCD’s mosaicked- MOPEX
Color-color and colormagnitude diagrams
The purpose of this study is to obtain more data
about known YSOs (young stellar objects) and
find more candidate YSOs.
• 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
Obtained images from the Spitzer Space Telescope on
Lynds Dark Nebulae 425 and 981 (Leopard)
Mosaics of LDN 425
Mosaics of LDN 981
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
Using these values SEDs (spectral energy
distributions) and Color-Color plots were made to
compare the YSO candidates to known YSOs.
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