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molecules:ism:ti-oxide [2019/02/25 22:38] – external edit 127.0.0.1molecules:ism:ti-oxide [2020/12/10 11:38] (current) – [Titanium Monoxide] mueller
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 ===== Titanium Oxides in Circumstellar Envelopes of Stars ===== ===== Titanium Oxides in Circumstellar Envelopes of Stars =====
  
-Absorption bands of **Titanium Monoxide**, **TiO**, in the visible have been identified in spectra of stars more than hundred years ago. In fact, these features are instrumental to classify M- and S-type stars. Moreover, TiO is thought to be responsible for the pulsation of Mira stars, one class of variable O-rich late-type stars. However, these features originate from the atmospheres of these stars, not from the circumstellar shells of these stars.+==== Titanium Monoxide ==== 
 + 
 + 
 +Absorption bands of  **TiO** in the visible have been identified in spectra of stars more than hundred years ago. In fact, these features are instrumental to classify M- and S-type stars. Moreover, TiO is thought to be responsible for the pulsation of Mira stars, one class of variable O-rich late-type stars. However, these features originate from the atmospheres of these stars, not from the circumstellar shells of these stars.
  
 A. R. Hyland, E. E. Becklin, G. Neugebauer, and G. Wallerstein,\\ A. R. Hyland, E. E. Becklin, G. Neugebauer, and G. Wallerstein,\\
 reported on the\\ reported on the\\
-**[[http://cdsads.u-strasbg.fr/abs/1969ApJ...158..619H|Observations of the Infrared Object, VY Canis Majoris]]**\\+**[[https://ui.adsabs.harvard.edu/abs/1969ApJ...158..619H|Observations of the Infrared Object, VY Canis Majoris]]**\\
 //Astrophys. J.// **158**, 619–628 (1969).\\ //Astrophys. J.// **158**, 619–628 (1969).\\
 They detected several "unidentified emission lines" toward this O-rich late-type star, which they called to be "associated with TiO band heads" (six times, one possibly overlapping with atomic Rb), "strong VO band here" (once), "probably ScO" (four times). Additional emission lines were firmly assigned to TiO (and VO) by\\ They detected several "unidentified emission lines" toward this O-rich late-type star, which they called to be "associated with TiO band heads" (six times, one possibly overlapping with atomic Rb), "strong VO band here" (once), "probably ScO" (four times). Additional emission lines were firmly assigned to TiO (and VO) by\\
 G. Wallerstein,\\ G. Wallerstein,\\
-**[[http://cdsads.u-strasbg.fr/abs/1971ApJ...169..195W|Spectroscopic Observations of VY Canis Majoris during 1969-1971]]**\\+**[[https://ui.adsabs.harvard.edu/abs/1971ApJ...169..195W|Spectroscopic Observations of VY Canis Majoris during 1969-1971]]**\\
 //Astrophys. J.// **169**, 195–197 (1971).\\ //Astrophys. J.// **169**, 195–197 (1971).\\
 The rotational temperature appears to vary greatly between about 500 K or even lower and about 900 K and suggests that the emission has its origin in the circumstellar envelope of the star rather than the photosphere. The rotational temperature appears to vary greatly between about 500 K or even lower and about 900 K and suggests that the emission has its origin in the circumstellar envelope of the star rather than the photosphere.
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 More recently,TiO emission lines in the optical have also seen toward U Equ by\\ More recently,TiO emission lines in the optical have also seen toward U Equ by\\
 C. Barnbaum, A. Omont, and M. Morris,\\ C. Barnbaum, A. Omont, and M. Morris,\\
-**[[http://cdsads.u-strasbg.fr/abs/1996A%26A...310..259B|The Unusual Circumstellar Environment of the Evolved Star, U Equulei]]**\\+**[[https://ui.adsabs.harvard.edu/abs/1996A%26A...310..259B|The Unusual Circumstellar Environment of the Evolved Star, U Equulei]]**\\
 //Astron. Astrophys.// **310**, 295–270 (1996).\\ //Astron. Astrophys.// **310**, 295–270 (1996).\\
 The temperature was estimated to be between 750 and 1500 K.\\ The temperature was estimated to be between 750 and 1500 K.\\
 TiO emission lines were also seen toward several other types of stars, among them comparatively prominently in:\\ TiO emission lines were also seen toward several other types of stars, among them comparatively prominently in:\\
-**[[http://dx.doi.org/10.1088/0004-6256/143/2/37|Optical TiO and VO Band Emission in Two Embedded Protostars: IRAS 04369+2539 and IRAS 05451+0037]]**\\+**[[https://doi.org/10.1088/0004-6256/143/2/37|Optical TiO and VO Band Emission in Two Embedded Protostars: IRAS 04369+2539 and IRAS 05451+0037]]**\\
 by\\ by\\
 L. A. Hillenbrand, G. R. Knapp, D. L. Padgett, L. M. Rebull, and P. M. McGehee,\\ L. A. Hillenbrand, G. R. Knapp, D. L. Padgett, L. M. Rebull, and P. M. McGehee,\\
-//Astron. J.// **143**, Art. No. 37 (2012).+//Astron. J.// **143**, Art. No. 37 (2012).\\
  
 More recently, the\\ More recently, the\\
-**[[http://dx.doi.org/10.1051/0004-6361/201219520|Discovery of a TiO Emission Band in the Infrared Spectrum of the S star NP Aurigae]]**\\+**[[https://doi.org/10.1051/0004-6361/201219520|Discovery of a TiO Emission Band in the Infrared Spectrum of the S star NP Aurigae]]**\\
 //Astron. Astrophys.// **543**, Art. No. L2 (2012);\\ //Astron. Astrophys.// **543**, Art. No. L2 (2012);\\
 and tentatively toward V899 Aql and RX Psc were reported by\\ and tentatively toward V899 Aql and RX Psc were reported by\\
 K. Smolders, T. Verhoelst, P. Neyskens, J. A. D. L. Blommaert, L. Decin, H. van Winckel, S. van Eck, G. C. Sloan, J. Cami, S. Hony, P. De Cat, J.Menu, and J. Vos.\\ K. Smolders, T. Verhoelst, P. Neyskens, J. A. D. L. Blommaert, L. Decin, H. van Winckel, S. van Eck, G. C. Sloan, J. Cami, S. Hony, P. De Cat, J.Menu, and J. Vos.\\
-A temperature of 600 K was estimated. Even if it is rather uncertain, it is again compatible with circumstellar origin of the emission.+A temperature of 600 K was estimated. Even if it is rather uncertain, it is again compatible with circumstellar origin of the emission.\\
  
-Finally, the detection of rotational transitions in the circumstellar envelope of VY CMa (and others) will be described in the **TiO<sub>2</sub>** section.+Finally, the detection of rotational transitions in the circumstellar envelope of VY CMa (and others) will be described in the **TiO<sub>2</sub>** section.\\
  
 +T. Danilovich, C. A. Gottlieb, L. Decin, A. M. S. Richards, K. L. K. Lee, T. Kamiński, N. A. Patel, K. H. Young, and K. M. Menten\\
 +investigated\\
 +**[[https://doi.org/10.3847/1538-4357/abc079|Rotational Spectra of Vibrationally Excited AlO and TiO in Oxygen-rich Stars]]**\\
 +//Astrophys. J.// **904**, Art. No. 110 (2020).\\
 +//J// = 11 → 10 transitions of TiO with Ω = 1, 2, and 3 were found in the circumstellar envelope of R Doradus up to //v// = 2 and that of IK Tauri up to //v// = 1.\\
  
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-The detection of **Titanium Dioxide**, **TiO<sub>2</sub>** between 279 and 355  and around 222.5 GHz employing the SubMillemeter Array (SMA) and the Plateau de Bure Interferometer(PdBI), respectively, has been described by\\+==== Titanium Dioxide ==== 
 + 
 +The detection of  **TiO<sub>2</sub>** between 279 and 355  and around 222.5 GHz employing the SubMillemeter Array (SMA) and the Plateau de Bure Interferometer(PdBI), respectively, has been described by\\
 T. Kamiński, C. A. Gottlieb, K. M. Menten, N. A. Patel, K. H. Young, S. Brünken, H. S. P. Müller, M. C. McCarthy, J. M. Winters, and L. Decin,\\ T. Kamiński, C. A. Gottlieb, K. M. Menten, N. A. Patel, K. H. Young, S. Brünken, H. S. P. Müller, M. C. McCarthy, J. M. Winters, and L. Decin,\\
-**[[http://dx.doi.org/10.1051/0004-6361/201220290|Pure Rotational Spectra of TiO and TiO<sub>2</sub> in VY Canis Majoris]]**\\+**[[https://doi.org/10.1051/0004-6361/201220290|Pure Rotational Spectra of TiO and TiO<sub>2</sub> in VY Canis Majoris]]**\\
 //Astron. Astrophys.// **551** (2013), Art. No. A113.\\ //Astron. Astrophys.// **551** (2013), Art. No. A113.\\
 27 transitions with //J// and //K<sub>a</sub>// up to 42 and 9, respectively, upper state energies between 25 and about 730 K, and signal-to-noise ratios between 3 and 37 have been detected in emission. In addition, rotational transitions of TiO were detected in that study for the first time. 8 fine structure components of four rotational transitions with //J'// between 7 and 11 were detected with significance. Two additional high-lying Ω = 3 components had signal-to-noise ratios smaller than three, albeit just barely for one.\\ 27 transitions with //J// and //K<sub>a</sub>// up to 42 and 9, respectively, upper state energies between 25 and about 730 K, and signal-to-noise ratios between 3 and 37 have been detected in emission. In addition, rotational transitions of TiO were detected in that study for the first time. 8 fine structure components of four rotational transitions with //J'// between 7 and 11 were detected with significance. Two additional high-lying Ω = 3 components had signal-to-noise ratios smaller than three, albeit just barely for one.\\
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 T. Kamiński, H. S. P. Müller, M. R. Schmidt, I. Cherchneff, K. T. Wong, S. Brünken, K. M. Menten, J. M. Winters, C. A. Gottlieb, and N. A. Patel,\\ T. Kamiński, H. S. P. Müller, M. R. Schmidt, I. Cherchneff, K. T. Wong, S. Brünken, K. M. Menten, J. M. Winters, C. A. Gottlieb, and N. A. Patel,\\
 reported on\\ reported on\\
-**[[http://dx.doi.org/10.1051/0004-6361/201629838|An observational study of dust nucleation in Mira (ο Ceti) – II. Titanium oxides are negligible for nucleation at high temperatures]]**\\+**[[https://doi.org/10.1051/0004-6361/201629838|An observational study of dust nucleation in Mira (ο Ceti) – II. Titanium oxides are negligible for nucleation at high temperatures]]**\\
 //Astron. Astrophys.// **599** (2017), Art. No. A59.\\ //Astron. Astrophys.// **599** (2017), Art. No. A59.\\
 The authors detect several emission lines of TiO and TiO<sub>2</sub> mostly with ALMA and with APEX. They detect not only lines of the main isotopolog (with <sup>48</sup>Ti), but also lines of minor Ti isotopic species, of which some appear to be unblended. The authors detect several emission lines of TiO and TiO<sub>2</sub> mostly with ALMA and with APEX. They detect not only lines of the main isotopolog (with <sup>48</sup>Ti), but also lines of minor Ti isotopic species, of which some appear to be unblended.
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-Contributor(s): H. S. P. Müller; 03, 2013; 03, 2017 +Contributor(s): H. S. P. Müller; 03, 2013; 03, 2017; 12, 2020
  
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