Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~astro/School/Talks/handson_gbt2.pdf Дата изменения: Mon Jul 18 03:25:20 2005 Дата индексирования: Sat Dec 22 10:45:47 2007 Кодировка: Поисковые слова: star

OUTLINE

OH MASERS / MEGAMASERS
Project: GBT 2 Jim Braatz Rachel Olsten, Christoph er AЯ orve, Laura GС mez, Marta Cu eto, Myriam Cruz

I. II. III. IV. V.

Definitions Science Background Observ ations Results Summary

Definitions
W hat is a Maser?
A maser is an optical amplifier that produces coherent microwaves due to stim ulated emissions. A maser line is the brightest spectral line in the radio universe. It highlights stars forming regions, dense circumstellar shells around evolved stars as well as circum nuclear disk around black holes of galactic nuclei.

W hat is a megamaser? A megamaser is an extragalactic source with an unprecedented isotropic lum inosity of ~103L It is a m illion times more lum inous than nearby sources of masers. Almost 100 OH type and 60 H2O type megamasers have been detected by this time.


Mi

crow ave

A

mplificati on b y

Sti

m ulated

Em

issions of

R

adiation

Science Background
Masers were discov ered more than 25 years ago. Research in this astronomical area has experience great growth due to interf erometric techniques. Masers are used f or the study of astronomical enviroments, where radiation is created and in through which it propagates.*

Science Background
Objects showing masers emissions:
Stars Gala xies Star form ing regions Supernovas


Science Background
Types of masers: OH H2 O SiO CH3 O H NH3 OH Megamasers
Most of th ese molecules are produced during th e birth process of a star du e to powerful shocks th at gen erates strong stellar win ds with h igh velocity that runs in to h igh density magn etized material.*

Observations
Sources observ ed:
W 3OH TCom RHya W Leo Arp220 Mrk231 IRAS 10173+08 Star form ing region Star Star Star Extragalactic source Extragalactic source* 28 Extragalactic source*

*These sources were observed with no clear results due to possible RFI and/or noise.

SOURCE : W3OH (ST AR F ORMING REGION)

GRAPHICS

SOURCE : T COM (ST AR)

SOURCE : RHYA (ST AR)


SOURCE : WLE O (ST AR)

SOURCE : ARP220 (EXT RAGL ACT IC S OURCE)
SOURCE S W3OH TCo m RHya WL e o Arp220 DISTA NCE S (p c ) 2200 1253 617 1220 Z=0.018

Results
TYPE SFR * * * EG INT. FLUX (Jy Km/s) 432.34 1 .9 7 17.05 1 .3 4 52.20 L/L (SNR) 3.6 10 (6 . 8 )
-6

Tsys (K) 41.52

RMS/Calc

0.02/0.017 0.01/0.009 0.01/0.008 0.01/0.009 0.008/0.006

5.2 10(1 4 . 9 ) 1.1 10 (5 . 9 )

9

15.05 16.67
9

-8

3.4 10(1 2 . 7 )

15.17 16.33

512 (701.9)

T abl e 1. Integrat ed fl uxes and lum inositi es.

Summary
Statistical analysis of masers can provide great inf ormation about the stages and ev olutionary schemes of the stellar population. Inf ormation that, otherwise, will stay completely hidden by thick dust shells in the univ erse.

Perspective
Great knowledge has been gathered f rom this project and we all know that this experience will be of impact and contribution to our prof essional dev elopment.


References
Benson' s Cat al og (1990; ApJS...74...911) Braat z, Jim, et. al s; 2005 Sum m er School Proj ect Abstract Elitzur, M.; Astronom ic al Masers; Annu. Rev. Astron. Astrophys.; 1992. 30:75-112* Engl e' s Cat al og (1979; 26AS... 36... 337) www.dam ir.iem .csic.es/PARDO http://ub.rug.nl/ el doc/di s/sci enc e/h.r.kl oekner/c3.pdf http://cdsweb.u-strasbg.fr/vi z-bin/Vizi eR?sourc e=J/A+A/397/213