John Carpenter's Home Page

John Carpenter

Department of Astronomy
California Institute of Technology
MS 105-24
Pasadena, CA 91125

Phone: (626)-395-4024
Email: jmc_at_astro.caltech.edu

Research

Circumstellar Disks in IC 348

I used the OVRO interferometer to search for circumstellar disks surrounding young stars in IC348. This figure shows the resulting mosaic, and the location of 95 known members of the IC 348 cluster. None of the stars are detected in the millimeter continuum at an intensity level of 3 sigma or greater. These observations imply that the 3 sigma upper limit to the disk mass around any individual star is 0.025 Msun, and that the average disk mass is 0.002 +/- 0.001 Msun. Compared with the minimum mass needed to form the planets in our solar system (about 0.01 Msun), the lack of massive disks and the low mean disk mass in IC 348 suggest either that planets more massive than a few Jupiter masses will form infrequently around 0.2-0.5 Msun stars in IC 348, or that the process to form such planets has significantly depleted the disk of small dust grains on time scales less than the cluster age of about 2 Myr. A preprint is available that describes this work in more detail.

Variability in Young Stars

This figure illustrates just one of the more spectacular examples of the variable stars we have identified toward the Orion A molecular cloud. Shown in this figure are the J, H, K, J-H, and H-K light curves, the J vs. J-H and K vs. H-K color-magnitude diagrams, and the J-H vs H-K color-color diagram for the time series data. Postage stamps of the J, H, and K images are also shown, along with a printed summary of the photometric characteristics. The results of this study are presented in Carpenter, Hillenbrand, & Skrutskie (2001). In addition, we are in the process of analyzing variability observations of the Chamaeleon I and Rho Oph star forming region. The Chamaeleon I results are now available!

Phase Corrected Images

An example of a phase corrected image obtained at the OVRO Millimeter Array produced using the OVRO 22 GHz water line monitors. The left panel is the image produced using normal astronomical phase corrections, and the left panel is the images after applying the phase corrections. This project is described in more detail at the OVRO WLM web page.

Stellar Population in Molecular Clouds

Image of the average J-K stellar color toward the Outer Galaxy derived from 2MASS star counts. The brighter colors represent larger J-Ks colors and indicate regions where background field stars and embedded young stars have been reddened by dust in molecular clouds. The Taurus, Perseus, Orion A, Orion B, and MonR2 molecular clouds are clearly visible, as well as numerous molecular clouds within the Galactic Plane. These data were used to analyze the distribution of stars in nearby molecular clouds. The paper describing the results can be found here.

IMF in the Orion Nebula Cluster

H and K mosaics of the Orion Nebula Cluster obtained with NIRC on Keck. A preprint (Hillenbrand & Carpenter 2000) can be found here.

	Circumstellar Disks in IC 348 I used the OVRO interferometer to search for circumstellar disks surrounding young stars in IC348. This figure shows the resulting mosaic, and the location of 95 known members of the IC 348 cluster. None of the stars are detected in the millimeter continuum at an intensity level of 3 sigma or greater. These observations imply that the 3 sigma upper limit to the disk mass around any individual star is 0.025 Msun, and that the average disk mass is 0.002 +/- 0.001 Msun. Compared with the minimum mass needed to form the planets in our solar system (about 0.01 Msun), the lack of massive disks and the low mean disk mass in IC 348 suggest either that planets more massive than a few Jupiter masses will form infrequently around 0.2-0.5 Msun stars in IC 348, or that the process to form such planets has significantly depleted the disk of small dust grains on time scales less than the cluster age of about 2 Myr. A preprint is available that describes this work in more detail.


	Variability in Young Stars This figure illustrates just one of the more spectacular examples of the variable stars we have identified toward the Orion A molecular cloud. Shown in this figure are the J, H, K, J-H, and H-K light curves, the J vs. J-H and K vs. H-K color-magnitude diagrams, and the J-H vs H-K color-color diagram for the time series data. Postage stamps of the J, H, and K images are also shown, along with a printed summary of the photometric characteristics. The results of this study are presented in Carpenter, Hillenbrand, & Skrutskie (2001). In addition, we are in the process of analyzing variability observations of the Chamaeleon I and Rho Oph star forming region. The Chamaeleon I results are now available!


	Phase Corrected Images An example of a phase corrected image obtained at the OVRO Millimeter Array produced using the OVRO 22 GHz water line monitors. The left panel is the image produced using normal astronomical phase corrections, and the left panel is the images after applying the phase corrections. This project is described in more detail at the OVRO WLM web page.


	Stellar Population in Molecular Clouds Image of the average J-K stellar color toward the Outer Galaxy derived from 2MASS star counts. The brighter colors represent larger J-Ks colors and indicate regions where background field stars and embedded young stars have been reddened by dust in molecular clouds. The Taurus, Perseus, Orion A, Orion B, and MonR2 molecular clouds are clearly visible, as well as numerous molecular clouds within the Galactic Plane. These data were used to analyze the distribution of stars in nearby molecular clouds. The paper describing the results can be found here.


	IMF in the Orion Nebula Cluster H and K mosaics of the Orion Nebula Cluster obtained with NIRC on Keck. A preprint (Hillenbrand & Carpenter 2000) can be found here.