IRAS sources beyond the solar circle. VI. Analysis of the FIR, H_2_O, and CO emission.

Details IRAS sources beyond the solar circle. VI. Analysis of the FIR, H_2_O, and CO emission. IRAS sources beyond the solar circle. VI. Analysis of the FIR, H_2_O, and CO emission.

Sep 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995a%26a...301..236w&link_type=abstract

Astronomy and Astrophysics, v.301, p.236

Astronomy and Astrophysics

Astrophysics

31

Masers, Stars: Pre-Main Sequence, Ism: Molecules, Infrared: Ism: Continuum, Radio Lines: Ism

Scientific paper

For a sample of 1357 IRAS sources with FIR colours of young stellar objects we have compared the occurrence and properties of H_2_O maser- and ^12^CO(1-0) emission with the observed and derived IRAS parameters. We find that the distribution of differences between the CO and H_2_O velocities is a Gaussian with a FWHM of about 11km/s. The mean velocity difference is nearly zero. The velocity of the peak H_2_O emission is not at a preferred location within the velocity interval where emission is detected. The H_2_O maser detection rate increases with both the FIR luminosity and the ^12^CO(1-0) line width: below log(L_FIR_/Lsun_)=3.5, less than 10% of the sources show maser emission, whereas H_2_O is detected towards almost all of the sources above log(L_FIR_/Lsun_)=4.5. For the sources with H_2_O maser emission, the average CO line width (FWHM about 5.0km/s) is approximately twice as large as for those without detected H_2_O emission, an effect which is independent of the sources' FIR luminosity. However a significant fraction of sources with no detected H_2_O emission still have line widths larger than 1.9km/s, the median value for the quiescent gas not associated with the IRAS sources. The maximum H_2_O maser luminosity at each FIR luminosity is proportional to L_FIR_: L_H_2_O_/Lsun_=10^-7.4^(L_FIR_/Lsun_). In IRAS colour-colour plots, sources can be distinguished in maser-like and non-maser-like sources according to their CO line widths and FIR luminosity. At a given L_FIR_ the maximum T^*^_A_ found for ^12^CO(1-0) decreases with distance from the Sun, likely due to beam filling effects. Few sources with maser emission have T^*^_A_ below 7.5K, when observed with the IRAM 30-m telescope. There is no difference in the maximum T^*^_A_ of sources with maser-like and non-maser-like IRAS colours. We have derived the intrinsic luminosity- and mass distribution of sources with (non)-maser-like IRAS colours, correcting for incompleteness effects at lower luminosities. The slope of the IMF for sources with maser-like colours and mass larger than 10Msun_ is found to be -2.8+/-0.3.

Affiliated with

Also associated with

No associations

Rating

IRAS sources beyond the solar circle. VI. Analysis of the FIR, H_2_O, and CO emission. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with IRAS sources beyond the solar circle. VI. Analysis of the FIR, H_2_O, and CO emission., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and IRAS sources beyond the solar circle. VI. Analysis of the FIR, H_2_O, and CO emission. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-821171