The Curious Case of Glass I: High Ionization and Variability of Different Types

Abstract

Our Spitzer IRS observation of the infrared companion Glass Ib revealed fine-structure emission with high ionization ([Ne iii]/[Ne ii] = 2.1 and [S iv]/[S iii] = 0.6) that indicates that the gas is likely illuminated by hard radiation. While models suggest that extreme-ultraviolet radiation could be present in T Tauri stars, this is the first detection of [S iv] and such a high [Ne iii]/[Ne ii] ratio in a young star. We also find that Glass Ib displays the molecules HCN, CO 2 , and H 2 O in emission. Here we investigate the Glass I binary system and consider possible mechanisms that may have caused the high ionization, whether from an outflow or disk irradiation. We also model the spectral energy distributions of Glass Ia and Ib to test if the system is a young member of the Chameleon I star-forming region, and we consider other possible classifications for the system. We find that Glass Ib is highly variable, showing changes in continuum strength and emission features at optical, near-infrared, and mid-infrared wavelengths. The optical light curve indicates that a central stellar component in Glass Ib became entirely visible for 2.5 years beginning in mid-2002 and possibly displayed periodic variability with repeated, short-period dimming during that time. As the fine-structure emission was not detected in observations before or after our Spitzer IRS observation, we explore whether the variable nature of Glass Ib is related to the gas being highly ionized, possibly due to variable accretion or an X-ray flare.

New companions in the stellar systems of DI Cha, Sz 22, CHXR 32, and Cha Hα5 in the Chamaeleon I star-forming region

“…As for the other targets, we used the brightnesses of the primaries to determine mean apparent magnitudes of the secondaries using the measured contrasts and assuming no significant variations; however, as for CHXR 32 A, 2MASS only gives upper limits in the H and K bands, so we use the brightnesses of H = 7.189 ± 0.114 mag and Ks = 6.182 ± 0.089 mag given in Carpenter et al (2002), reflecting the strong extinction of the primary. According to the photometry (Table 9) the secondary component of this now resolved triple star consists of an M1 (K6 -M3.5) type star with an M3.5 (M2.5 -M5.5) companion, compatible with the unresolved H-Ks colour measured for B & C. We note, however, that there are strong systematic errors because the J band brightness varies by 2.3 σ between 2MASS and Carpenter et al (2002), while the visible light curve varies up to about 2 mag according to ASAS data presented in Kruger et al (2013).…”

“…According to the photometry (Table 9) the secondary component of this now resolved triple star consists of an M1 (K6−M3.5) type star with an M3.5 (M2.5−M5.5) companion, compatible with the unresolved H − Ks colour measured for B and C. We note, however, that there are strong systematic errors because the J band brightness varies by 2.3σ between 2MASS and Carpenter et al (2002), while the visible light curve varies up to about 2 mag according to ASAS data presented in Kruger et al (2013).…”

“…The present discrepancy in UCAC3 can most likely be explained by Kruger et al (2013), could lead to further discrepancies. Please see this publication for further discussion of the proper motion behaviour of the system.…”

“…If epochs from near-infrared catalogues, in which the extincted CHXR 32 A is dominant, are mixed with those from optical catalogues, in which CHXR 32 BC are the dominant sources, the spatial separation of ∼2.4 arcsec between A & BC can be misinterpreted as a deviation from the real proper motion within the epoch differences of several years. The strong photometric variability in ASAS data between 2002 to 2004 in CHXR 32 A reported in Kruger et al (2013), could lead to further discrepancies. Please see this publication for further discussion of the proper motion behaviour of the system.…”

The Gas Disk: Evolution and Chemistry

“…The [Ne III] line (15.55 µm) on the other hand is detected only in a handful of objects (e.g., Kruger et al 2013, Espaillat et al 2013. Espaillat et al (2013) tested the possibility of the lines being emitted by an X-ray and EUV irradiated disk.…”