Star formation in lynds dark nebulae
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Star Formation in Lynds Dark Nebulae. Ashley Peter, Willly Wassmer, Rose Haber. Abstract.

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Star Formation in Lynds Dark Nebulae

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Star formation in lynds dark nebulae

Star Formation in Lynds Dark Nebulae

Ashley Peter, Willly Wassmer, Rose Haber


Abstract

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.


Star formation in lynds dark nebulae

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


Why infrared galaxies at many wavelengths

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)


Star formation in lynds dark nebulae

Spitzer Telescope

(October 2000)

(IRAC)

(MIPS)


Lynds 1014

Lynds 1014

IR

Visible

600 LY away


Lynds 425 and 981

Lynds 425 and 981

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


Formation of a low mass star

Formation of a low mass star

Class 0

Class I

Class II

Class III

Greene, American Scientist, Jul-Aug 2001


Star formation in lynds dark nebulae

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


Irac color color diagrams

IRAC Color-Color Diagrams

Class I (envelope) models

Av=30

Class II (disk) models

Allen et al. 2004


Star formation in lynds dark nebulae

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


Star formation in lynds dark nebulae

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


Star formation in lynds dark nebulae

Connelley, Michael et al. “Infrared Nebulae Around Young Stellar Objects.”

IRAS Point and Faint Source Catalogs

Class I YSOs

SEDs


Star formation in lynds dark nebulae

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


Purpose

Purpose

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


Hypotheses

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


Methodology

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.


Bibliography

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.


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