2002 REU/PIA Projects
- Search for Galaxy Clusters in the Fields of QSOs / Follow_up Observations of Deep Lens Survey Transients - Pamela Baca
- Optical Studies of the Vela Bullets - Jeffrey Carlin
- From Binaries to Triples - Tucker Freismuth
- The Disk Tilt of the LMC - Colette Salyk
- K-correction Calculations for Type Ia Supernovae -Marcelo Mora
- The Darkness of the Chilean Night Sky - Sergio Vera
- Precision photometry for Type Ia supernovae - Miguel Verdugo
- Infrared Spectra of SiO Masing AGB Stars in the Galactic Bulge - Amber Young
Search for Galaxy Clusters in the Fields of QSOs / Follow_up Observations of Deep Lens Survey Transients
Pamela Baca - University of Colorado, Denver
We examine evidence for gravitational lensing of quasi-stellar objects due to an overdensity of foreground galaxy clusters.
Studies of bright quasars have shown correlation between these background sources and foreground galaxies (Norman and Impey 2001 and references within). This suggests that these quasars appear intrinsically brighter as a result of their location behind large mass structures. Further studies (Fort et. Al., 1995) have demonstrated that there exists weak lensing of distant galaxies in the fields of some quasars. In order to investigate this weak lensing generally, more information about the mass structures themselves is needed.
We examine several quasar fields, in which quasars have redshifts of 0.7 < z < 2.5, in 4 SDSS filters (ugri) with the 1.5m telescope at CTIO. We will determine the photometric redshifts of galaxies in these fields in order to look for associated foreground clusters.
As photometric redshifts are much less time consuming to obtain than spectroscopic redshifts, they are a good alternate means for initial determination of the presence of structures and thus a good indicator as to whether or not more difficult to obtain spectroscopic data should be pursed.
We propose to take photometric follow-up observations of the brighter (V < 23) newly discovered, stationary Deep Lens Survey (DLS) transient objects with the 1.5m telescope at CTIO.
The discovery of these transients is a "by-product'' of this wide-field survey. Currently, there is no systematic effort made by the survey team to follow these discoveries in time intervals or with additional filters that might facilitate the identification of these objects.
Based on 2 years of past DLS observations, we expect 3-5 bright, stationary transients with stellar progenitors to be discovered each month during the 2001 DLS observing runs. These objects will be targeted for multicolor (BVRI) observations over an additional 2 nights during each month. This baseline will give us sensitivity to the multiple timescales over which we expect known astronomical objects to vary.
This additional photometric data will enable us to classify these objects as cataclysmic variables ,orphan gamma ray burst afterglows and AGN. These classifications will be based on the observed colors and light curves of the targets. Further we hope that some of these observations might even lead to discoveries of entirely unanticipated objects. We intend to use this limited amount of data to define a project that can suitably be carried out by high school teachers and students as part of the Research Based Science Education program.
In 1995, Aschenbach, et al identified X-ray emission from the direction of the Vela supernova remnant which seemed to be associated with the remnant but was outside the nominal shell. It was proposed that these extensions were "bullets" of material which had been ejected at high velocity when the progenitor went supernova. Other SNRs (Hughes, 1996- Tycho's SNR, Willingale, 2002- Cas A) have been shown to have such features. We have imaged the positions of these X-ray features with the UM/CTIO Curtis Schmidt telescope and have discovered optical emission coming from the locations of several of the Vela "bullets". The summer project will involve reduction of these optical images, as well as some associated spectroscopic data, to determine the nature of the optical emission and hopefully learn more about the nature of these bullets.
There are indications that close (spectroscopic) binaries are formed within higher-order multiples. If so, many (or all?) binaries must have tertiary components. We shall check this. For a selection of 20-50 nearby late-type and apparently "single" close binaries, images in B,R filters will be taken at the 0.9m telescope and suitable tertiary candidates will be identified on color-magnitude diagrams. These candidates were missed previously because old visual catalogs are incomplete beyond 10-th magnitude. To confirm the candidates, further research will be done with existing databases (proper motions from Tycho or from comparison with DSS images), possibly radial velocities will be measured later as well.
No abstract available, sorry for the inconvenient
K-correction Calculations for Type Ia Supernovae
Marcelo Mora - Pontificia Universidad Católica de Chile, Santiago
Imagine that we see a star far away from us and suddenly it explodes and become in a supernova and, if we are lucky, this supernova will be a Type Ia (without emission H lines). We will see the light of this supernova reddened so the goal of the K-correction try to "see" the supernova like it's own reference frame.
But a good K-correction must include the atmospheric and the instruments distortion. For that we are working in synthetic photometry made with standards stars.
The Darkness of the Chilean Night Sky
Sergio Vera - Pontificia Universidad Católica de Chile, Santiago
No abstract available, sorry for the inconvenient
Precision photometry for Type Ia supernovae
Miguel Verdugo - Pontificia Universidad Católica de Chile, Santiago
We have created an atlas of near-infrared and optical light curves taken from the literature and from our unpublished JHK data of nearby SNe observed at CTIO and LCO. Our objective was to determine whether or not Type Ia supernovae are standardizable candles in the near-infrared. The preliminary conclusions are: a) The morphology of the infrared light curves does not form a simple monotonically changing sequence when organized as a function of evolutionary speed (Dm_15(B)). Apparently a few SNe which are otherwise normal in the optical seem to have anomalous near-infrared light curves, especially in the J-band. This makes it difficult to construct a single-parameter family of templates that characterize the infrared light curves. However, in general there is a pattern to these light curves in the sense that the secondary maximum occurs later and more strongly for slower-declining SNe. But, as shown in Krisciunas et al. (2001) for the I-band, there are exceptions to this trend. b) H-band absolute magnitudes 10 days after the time of B-band maximum are essentially constant at -17.91 and not a function of Dm_15(B). c) We obtain a Hubble constant of 71.5 +/- 2.5 km/s/Mpc and a dispersion of +/-0.24 mag in the H-band Hubble diagram.
Infrared Spectra of SiO Masing AGB Stars in the Galactic Bulge
Amber Young - Middlebury College, Vermont
Our 86 GHz (v=1, J=2->1) SiO maser survey with the 30-m IRAM telescope of a sample of late-type stars in the inner Galaxy has doubled the number of stellar (mostly AGB stars) line-of-sight velocities known at low latitude (|b|<0.5). This large sample of stars allows us to isolate two kinematic populations: one associated with the gaseous nuclear disk and the other with the Galactic bulge and/or inner Galactic disk. We propose to obtain near infrared spectra of these two kinematiclly selectred groups. We will perform a comparative analysis of their photospheric absorption features to search for clues to their formation history. In particular, we will address the question of how the stellar nuclear disk relates to the Bulge and inner Galactic disk.