相关论文: Tracking the evolutionary stage of protostars by t…
An important tracer of the origin and evolution of cometary ices is the comparison with ices found in dense clouds and towards Young Stellar Objects (YSOs). We present a survey of ices in the 2-5 micron spectra of 23 massive YSOs, taken…
Icy grain mantles are commonly observed through infrared spectroscopy toward dense clouds, cloud cores, protostellar envelopes and protoplanetary disks. Up to 80% of the available oxygen, carbon and nitrogen are found in such ices; the most…
Aims. To understand the roles of infall and protostellar evolution on the envelopes of massive young stellar objects (YSOs). Methods. The chemical evolution of gas and dust is traced, including infall and realistic source evolution. The…
A rich inventory of complex organic molecules (COMs) has been observed in high abundances in the gas phase toward Class 0 protostars. These molecules are suggested to be formed in ices and sublimate in the warm inner envelope close to the…
Currently ~36 different absorption bands have been detected in the infrared spectra of cold, dense interstellar and circumstellar environments. These are attributed to the vibrational transitions of ~17 different molecules frozen on dust…
Ices regulate much of the chemistry during star formation and account for up to 80% of the available oxygen and carbon. In this paper, we use the Spitzer c2d ice survey, complimented with data sets on ices in cloud cores and high-mass…
Young stars exhibit variability due to changes in the gas accretion rate onto them, an effect that should be quite significant in the early stages of their formation. As protostars are embedded within their natal cloud, this variability may…
Hot cores and their precursors contain an integrated record of the physics of the collapse process in the chemistry of the ices deposited during that collapse. In this paper, we present results from a new model of the chemistry near high…
Protoplanetary disk ice lines shape a multitude of planet formation processes, setting the environmental composition through evolution. Ice line locations depend on molecular sublimation and deposition properties, but in dynamic disks where…
(Abridged) Aims & Methods. A two-dimensional, semi-analytical model is presented that follows, for the first time, the chemical evolution from a collapsing molecular cloud (a pre-stellar core) to a protostar and circumstellar disk. The…
Ices are an important constituent of protoplanetary disks. New observational facilities, notably the James Webb Space Telescope (JWST), will greatly enhance our view of disk ices by measuring their infrared spectral features. We present a…
(Abridged) Classification schemes for YSOs are based on evaluating the degree of dissipation of the surrounding envelope, whose main effects are the extinction of the optical radiation from the central YSO and re-emission in the…
We present Spitzer IRS spectroscopy of CO2 ice bending mode spectra at 15.2 micrometer toward 19 young stellar objects with luminosity lower than 1 Lsun (3 with luminosity lower than 0.1 Lsun). Ice on dust grain surfaces can encode the…
Measuring properties of young stellar objects (YSOs) is necessary for probing the pre-main-sequence evolution of stars. As YSOs exhibit complex geometry, measurement generally entails comparing observed radiation to template populations of…
The evolution of deeply embedded young stellar objects (YSOs) has traditionally been traced through dust continuum spectral energy distributions (SEDs), but the use of CO excitation as an evolutionary probe has not yet been explored due to…
We investigate the chemical history of interstellar OCS and SO2 by deriving a statistically-significant sample of gas-phase column densities towards massive protostars and comparing to observations of gas and ices towards other sources…
The study of the chemical evolution of gas and dust from pre-stellar dense cores to circumstellar disks around young stars forms an essential part of understanding star- and planet formation. Throughout the collapse- and protostellar…
The physical conditions in a collapsing cloud can be traced by observations of molecular lines. To correctly interpret these observations the abundance distributions of the observed species need to be derived. The chemistry in a collapsing…
We model how the mid-infrared colors of Young Stellar Objects (YSOs) vary with stellar temperature. The spectral energy distribution (SED) of each object has contributions from thermal emission of circumstellar dust, from direct stellar…
We have obtained the full 1-200 um spectrum of the low luminosity (36 Lsun) Class I protostar Elias 29 in the Rho Ophiuchi molecular cloud. It provides a unique opportunity to study the origin and evolution of interstellar ice and the…