Advisors greg doppmann and bernadette rodgers nsf ctio reu 2006
Download
1 / 14

Spectroscopic Investigation of Companion Stars in Herbig Ae/Be Binary Systems Anne Sweet - PowerPoint PPT Presentation


  • 99 Views
  • Uploaded on

Advisors: Greg Doppmann and Bernadette Rodgers NSF CTIO REU 2006. Spectroscopic Investigation of Companion Stars in Herbig Ae/Be Binary Systems Anne Sweet. Introduction:. What are Herbig AeBe Stars? -Pre-Main Sequence (PMS) - 2 < Msun < 8 -associated with a star forming regions

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Spectroscopic Investigation of Companion Stars in Herbig Ae/Be Binary Systems Anne Sweet' - aoife


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Advisors greg doppmann and bernadette rodgers nsf ctio reu 2006

Advisors: Greg Doppmann and Bernadette Rodgers

NSF CTIO REU 2006

Spectroscopic Investigation of Companion Stars in Herbig Ae/Be Binary SystemsAnne Sweet


Introduction
Introduction:

What are Herbig AeBe Stars?

-Pre-Main Sequence (PMS)

- 2 < Msun < 8

-associated with a star forming regions

-IR excess and/or emission lines

Why are we studying these systems?

-binary fraction and the initial mass function

-possibility of direct mass measurement

-stellar evolution as a function of mass

-the effects of PMS Herbig stars on the evolution of low mass counterparts --> HR diagram

Why are we using the IR?

-environments associated with Young Stellar Objects (YSOs) make the IR the most effective and ideal waveband


Data:

Sample Selection

-Herbig stars with known companions and a binary separation of less than 0.8''

Observations

-MK Standards: GNIRS 111 1/mm grating, R =18,000

-CO Ori A and B: 32 1/mm grating, R=1,800

-HR 5999B: GNIRS 111 1/mm grating, R =18,000

-BF Ori B: GNIRS 111 1/mm grating, R =6,000

Reductions

-images reduced in IRAF

-telluric correction applied using xtellcor in IDL


Spectral analysis
Spectral Analysis:

Two methods used, both utilizing the Ames models (Hauschildt 2003-private communication)

1) High Resolution Analysis (R=18,000)

-matches spectral synthesis models with data to find the best pixel to pixel fit across absorption lines (Na lines at 2.2 microns, CO bandhead at 2.3 microns)

-used with: MK standards, HR5999B (Na only), BF Ori B (Na only)

2) Medium Resolution Analysis (R=6,000)

-overplots models on data for a qualitative eye fit

-uses equivalent widths of models and data for a quantitative comparison.

-used with CO Ori A and B and BF Ori B.

For both methods, data must be late type!


High resolution analysis fitting line shapes
High Resolution Analysis: Fitting Line Shapes

-Using Na and CO portions of the spectra.

-Process (Doppmann 2003):

-input .txt file

-select relevant region

-input a specific value for log(g), and give a range of values for vsini, shift and Teff.

-iterate to minimize RMS


High resolution analysis standards
High Resolution Analysis: Standards

-8 standards, K0-M0.5, luminosity class III

-used for calibrating technique to literature

-well correlated, but systematically offset from published data

-other models were considered, but discarded due to limited atmospheres.



High resolution analysis bf ori b
High Resolution Analysis: BF Ori B

-R=6,000 data

-We applied two fits with different fixed logg values for a decent result- useful for comparison with medium resolution result.


Medium resolution fitting line strengths
Medium Resolution: Fitting Line Strengths

-Program overplots models on data for a qualitative fit comparison

-with the generated models, measure equivalent widths of strong lines and compare to equivalent widths of data.

-Na lines of BF Ori B shown on left, note changes in lines with increasing temp.


Medium resolution analysis equivalent widths
Medium Resolution Analysis: equivalent widths

10 strong lines chosen across 5 different orders (Na, Ti, Al)


Medium resolution bf ori b eqw analysis
Medium Resolution: BF Ori B EQW analysis

-

Green: Logg=3.5, Blue: Logg=4.5, red: EQW of data with errors


Conclusions
Conclusions:

-put these results on an H-R diagram!!

-by identifying spectral type, identify how many are late-type and compare to the T Tauri stars (PMS without nearby Herbig star) to say something about the effect that a massive star has on low mass stellar formation.

-Questions this brings up....


Thanks to
Thanks to:

-Greg and Bernadette for being fantastic mentors (and Peter for always trying to give me the day off)

-Stella, best REU mom EVER

-the other REUers for breaking the harassment/decency code JUST about every day.

-NSF for this wonderful research opportunity!!


ad