Browsing by Subject "variables: t tauri, herbig ae/be"

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An Analysis Of The Environments Of Fu Orionis Objects With Herschel
(2013-08) Green, Joel D.; Evans, Neal J.; Kospal, Agnes; Herczeg, Gregory; Quanz, Sascha P.; Henning, Thomas; van Kempen, Tim A.; Lee, Jeong-Eun; Dunham, Michael M.; Meeus, Gwendolyn; Bouwman, Jeroen; Chen, Jo-Hsin; Gudel, Manuel; Skinner, Stephen L.; Liebhart, Armin; Merello, Manuel; Green, Joel D.; Evans, Neal J.; Merello, Manuel
We present Herschel-HIFI, SPIRE, and PACS 50-670 mu m imaging and spectroscopy of six FU Orionis-type objects and candidates (FU Orionis, V1735 Cyg, V1515 Cyg, V1057 Cyg, V1331 Cyg, and HBC 722), ranging in outburst date from 1936 to 2010, from the "FOOSH" (FU Orionis Objects Surveyed with Herschel) program, as well as ancillary results from Spitzer Infrared Spectrograph and the Caltech Submillimeter Observatory. In their system properties (L-bol, T-bol, and line emission), we find that FUors are in a variety of evolutionary states. Additionally, some FUors have features of both Class I and II sources: warm continuum consistent with Class II sources, but rotational line emission typical of Class I, far higher than Class II sources of similar mass/luminosity. Combining several classification techniques, we find an evolutionary sequence consistent with previous mid-IR indicators. We detect [O I] in every source at luminosities consistent with Class 0/I protostars, much greater than in Class II disks. We detect transitions of 13CO (J(up) of 5-8) around two sources (V1735 Cyg and HBC 722) but attribute them to nearby protostars. Of the remaining sources, three (FU Ori, V1515 Cyg, and V1331 Cyg) exhibit only low-lying CO, but one (V1057 Cyg) shows CO up to J = 23 -> 22 and evidence for H2O and OH emission, at strengths typical of protostars rather than T Tauri stars. Rotational temperatures for "cool" CO components range from 20 to 81 K, for similar to 10(50) total CO molecules. We detect [C I] and [N II] primarily as diffuse emission.
Emission From Water Vapor And Absorption From Other Gases At 5-7.5 Mu M In Spitzer-Irs Spectra Of Protoplanetary Disks
(2014-09) Sargent, B. A.; Forrest, W.; Watson, D. M.; D'Alessio, P.; Calvet, N.; Furlan, E.; Kim, K. H.; Green, J.; Pontoppidan, K.; Richter, I.; Tayrien, C.; Green, J.
We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 mu m spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 mu m due to the nu(2) = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 mu m, which for some is consistent with gaseous formaldehyde (H2CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.