IC 2118 Current Research Activities
- 1 General Background on young stars
- 2 Color-Color Plots
- 3 Presentations, Posters, and Research Papers for IC2118
- 4 Information for Oil City High School meetings
The next meeting should be at 4 0'clock pm wednesday the 25th at matt walentosky's house. (Specifically for people going to California, so we can plan out events and travel...)
SUPPORT INFORMATION - T-Tauri Candidates Emit Radio
FROM MATT WALENTOSKY 6/30/2007 @ 2:30 PM - Two Abstracts Below
Title: Radio emission from pre-main-sequence stars Authors: Skinner, Stephen Lee
Affiliation: AA(Colorado Univ., Boulder.) Publication: Ph.D. Thesis Colorado Univ., Boulder. Publication Date: 01/1992 Category: Space Radiation Origin: STI
Abstract This study focuses on the properties and physical origin of radio continuum emission from pre-main-sequence (PMS) stars. These are young stars, typically less than a few million years old, and are still in a phase of gravitational contraction that will ultimately be halted by the onset of hydrogen burning in their cores. First, I address the question of the origin of centimeter continuum emission in intermediate mass (approx. equal to 3-20 solar mass) PMS stars, the so-called 'Herbig Ae/Be stars'. A high-sensitivity radio survey of 57 such stars was undertaken using the Very Large Array and Australia Telescope, resulting in the detection of twelve stars. These observations provide a homogenous data base consisting of information on source sizes, radio luminosities, variability timescales, circular polarization, and spectral energy distributions in the wavelength range 2-20 cm. Using these data along with previously published spectroscopy, I conclude that centimeter radio emission from Herbig Ae/Be stars is predominantly thermal and in many cases wind-related. An unexpected result of the above program was the serendipitous detection of circularly polarized radio emission in the low mass (approx. equal to 1 solar mass) PMS star Hubble 4, a member of the class of 'weak-lined T Tauri stars' (WTTS). This provides some of the most convincing evidence to date for the existence of ordered magnetic fields in WTTS. In a second observing program, I have searched for evidence of cold (less than or equal to 50 K) circumstellar dust around WTTS, which might exist in the form of remnant disks. Of the sixteen WTTS that were observed in the wavelength range 450-1100 microns using the James Clerk Maxwell Telescope, only V836 Tau was detected. Its spectral energy distribution longward of 10 microns is consistent with that expected for a flat, axisymmetric circumstellar disk of mass approx. equal to 0.04 solar mass (= 42 Jupiter masses). This star may be a rare example of an object in which disk dispersal is underway, but not yet complete.
Title: Centimeter Radio Emission from Low-Mass Weak T Tauri Stars in Taurus-Auriga Authors: Chiang, Eugene; Phillips, R. B.
Affiliation: AA(MIT), AB(MIT Haystack Observatory) Publication: American Astronomical Society, 185th AAS Meeting, #48.08; Bulletin of the American Astronomical Society, Vol. 26, p.1388 Publication Date: 12/1994 Origin: AAS Abstract Copyright:(c) 1994: American Astronomical Society
Abstract We report on the results of a sensitive survey for lambda 3.6 cm radio emission from low-mass, weak T Tauri (WTT) stars in the Taurus-Auriga cloud complex. The target population consists of stars in the Herbig and Bell Catalog of spectral type K7 or later, and W(Hα ) <= 10 Angstroms. Of the 28 such stars surveyed using the Very Large Array down to detection thresholds of ~ 0.1 mJy, 7 (possibly 8) are observed to emit at strengths ranging from 0.1 to 2 mJy. Five of these young radio stars are newly discovered in our survey: V827 Tau and V710 Tau B are discovered to be relatively strong sources of mJy emission, while IW Tau, UX Tau B, and the possible detection LkHa 332-G1 form a new population of relatively weak emitters. Our radio survey and complementary surveys are pooled, and of 43 WTT stars K7 or later in Tau-Aur, 14 are now known to be radio emitters at lambda 6 and lambda 3.6 cm. Correlations between radio luminosity and other stellar parameters have been attempted but generally yield null results. Wide binarity (component separations in excess of 0.13, 20 AU) appears unrelated to radio emission, as does spectral type. Furthermore, we find no convincing evidence for the extreme youth of radio stars, contrary to claims in the literature over the past decade. While we do find that radio-loud stars in our sample are formally younger than the radio-quiet stars by about 0.5 Myr, the reality of this relatively small age difference is highly suspect given uncertainties in the placement of these stars on the HR diagram. Moreover, Monte Carlo-type calculations involving distributing the stars on both the HR diagram and local CO gas density cast doubts on any differences between the radio stars and the general WTT population. We conclude that the age effect for low-mass radio WTT stars in Tau-Aur, if real, is much smaller than previous estimations by factors of 4-10. It is also possible centimeter wavelength surveys to date have still not properly described the radio luminosity function of low-mass WTT stars in Tau-Aur, and we urge future observations of these young stars with denser temporal coverage.
FROM SPUCK 6/30/2007 @ 2:35pm
I'm not sure that we will be able to use the GBT telescope in Green Bank for observations. The beamwidth at 10-15 GHz is probably too big.
Here are the specs for the GBT Beamwidth (Table 3) Diffraction beamwidth (FWHM) 8 GHz it is 90", 20 GHz it is 36", 50 GHz it is 14"
Here are some questions from Sue Ann Heatherly at NRAO-Green Bank - One question I have is: is the resolving power of the GBT sufficient to distinguish spatially between individual stars? Does large scale emission exist within the nebula that will confuse your results?
The VLA is probably the only instrument that can be used.
Synthesized Beamwidth (arcsec)depending on configuration
Nick Kelley 6/30/2007 3:00PM
400 cm 24.0" 80.0" 260.0" 850.0"
90 cm 6.0" 17.0" 56.0" 200.0"
20 cm 1.4 " 3.9" 12.5" 44.0"
6 cm 0.4 " 1.2""" 3.9 " 14.0 "
3.6 cm 0.24 " 0.7" 2.3 " 8.4 "
2 cm 0.14 " 0.4 " 1.2" 3.9"
1.3 cm 0.08 " 0.3" 0.9 "2.8"
0.7 cm 0.05 0.15 0.47 1 restricting my creativity
Generating Light Curves
Using Perth Telescope
1. Check to see what the current sky conditions are by checking the live camera
2. Check to see what the current weather conditions are
3. Weather forecast for Perth - http://www.bom.gov.au/weather/wa/
Log into telescope if conditions look good.
EMAIL firstname.lastname@example.org for telescope access
To date no X-Ray data for IC2118 has been located. If you know of any please contact Tim Spuck at email@example.com.
In January of 2007 students from Oil City High School used the 0.9 Meter Telescope at Kitt peak to image regions of IC2118 in H-alpha.'
Matt Walentosky, Nick Kelley, Sandy Weiser were the students who went!!!!!!
U, B, V, R, and I data will be used to generate more accurate SEDs for the T-Tauri Candidates
Visible outflows or jets are strong evidence that a candidate is indeed a T-Tauri Star
Images and Methods
FROM SPUCK 6/30/2007 See Image Below- IC 2118 3.6 µm (blue), 5.8 µm (green), 8.0 µm (red) tri-color composite generated using MaxIm DL. (By M. Heath, N. Kelley, P. Morton, M. Walentosky, S. Weiser – Oil City High School, Oil City, PA)