Pure rotational spectra of TiO and TiO<sub>2</sub>in VY Canis Majoris

Kamiński, T.; Gottlieb, C. A.; Menten, K. M.; Patel, Nimesh; Young, Ken; Brünken, Sandra; Müller, H. S. P.; McCarthy, Michael; Winters, J. M.; Decin, L.

doi:10.1051/0004-6361/201220290

Cited by 86 publications

(74 citation statements)

References 48 publications

(76 reference statements)

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“…The observations of IK Tau were carried out in the same setup as and contemporaneously with the observations of VY CMa. Kamiński et al (2013a) reported on some first results for the latter. Further results and more detailed descriptions of both surveys will be described in upcoming publications.…”

Section: Sma: Unbiased Survey Covering 279-355 Ghzmentioning

confidence: 99%

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

Beck

Kamiński

Patel

et al. 2013

A&A

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Context. Phosphorus-bearing compounds have only been studied in the circumstellar environments of the asymptotic giant branch star IRC +10 216 and the protoplanetary nebula CRL 2688, both carbon-rich objects, and the oxygen-rich red supergiant VY CMa. The current chemical models cannot reproduce the high abundances of PO and PN derived from observations of VY CMa. No observations have been reported of phosphorus in the circumstellar envelopes of oxygen-rich asymptotic giant branch stars. Aims. We aim to set observational constraints on the phosphorous chemistry in the circumstellar envelopes of oxygen-rich asymptotic giant branch stars, by focussing on the Mira-type variable star IK Tau. Methods. Using the IRAM 30 m telescope and the Submillimeter Array, we observed four rotational transitions of PN (J = 2−1, 3−2, 6−5, 7−6) and four of PO (J = 5/2−3/2, 7/2−5/2, 13/2−11/2, 15/2−13/2). The IRAM 30 m observations were dedicated line observations, while the Submillimeter Array data come from an unbiased spectral survey in the frequency range 279−355 GHz. Results. We present the first detections of PN and PO in an oxygen-rich asymptotic giant branch star and estimate abundances X(PN/H 2 ) ≈ 3 × 10 −7 and X(PO/H 2 ) in the range 0.5−6.0 × 10 −7 . This is several orders of magnitude higher than what is found for the carbon-rich asymptotic giant branch star IRC +10 216. The diameter ( 0. 7) of the PN and PO emission distributions measured in the interferometric data corresponds to a maximum radial extent of about 40 stellar radii. The abundances and the spatial occurrence of the molecules are in very good agreement with the results reported for VY CMa. We did not detect PS or PH 3 in the survey. Conclusions. We suggest that PN and PO are the main carriers of phosphorus in the gas phase, with abundances possibly up to several 10 −7 . The current chemical models cannot account for this, underlining the strong need for updated chemical models that include phosphorous compounds.

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Section: Sma: Unbiased Survey Covering 279-355 Ghzmentioning

confidence: 99%

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

Beck

Kamiński

Patel

et al. 2013

A&A

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“…TiO electronic bands are sufficiently prominent in stellar photospheres of O-rich stars for them to be used for classification purposes (Morgan & Keenan 1973). In fact, a titanium isotopic analysis using TiO spectra has been conducted toward the Mira variable o Ceti (Wyckoff & Wehinger 1972 Kaminski et al 2013). This discovery helps link photospheric and circumstellar molecules.…”

Section: Introductionmentioning

confidence: 99%

MILLIMETER/SUBMILLIMETER SPECTROSCOPY OF TiO (X³Δ_r): THE RARE TITANIUM ISOTOPOLOGUES

Lincowski

Halfen

Ziurys

2016

ApJ

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Pure rotational spectra of the rare isotopologues of titanium oxide, 46 TiO, 47 TiO, 49 TiO, and 50 TiO, have been recorded using a combination of Fourier transform millimeter-wave (FTmmW) and millimeter/submillimeter direct absorption techniques in the frequency range 62-538 GHz. This study is the first complete spectroscopic characterization of these species in their X 3 Δ r ground electronic states. The isotopologues were created by the reaction of N 2 O or O 2 and titanium vapor, produced either by laser ablation or in a Broida-type oven, and observed in the natural Ti isotopic abundances. Between 10 and 11 rotational transitions J + 1 « J were measured for each species, typically in all 3 spin-orbit ladders Ω=1, 2, and 3. For 47 TiO and 49 TiO, hyperfine structure was resolved, originating from the titanium-47 and titanium-49 nuclear spins of I=5/2 and 7/2, respectively. For the Ω=1 and 3 components, the hyperfine structure was found to follow a classic Landé pattern, while that for Ω=2 appeared to be perturbed, likely a result of mixing with the nearby isoconfigurational a 1 Δ state. The spectra were analyzed with a case (a) Hamiltonian, and rotational, spin-orbit, and spin-spin parameters were determined for each species, as well as magnetic hyperfine and electric quadrupole constants for the two molecules with nuclear spins. The most abundant species, 48 TiO, has been detected in circumstellar envelopes. These measurements will enable other titanium isotopologues to be studied at millimeter wavelengths, providing Ti isotope ratios that can test models of nucleosynthesis.

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“…This survey yielded the detection of ten more new species in the envelope of VY CMa, namely HCN, HNC, HCO + , CN, NS, PN, PO, NaCl, AlO, and AlOH. These studies will soon be complemented with the results from the full spectral surveys that have been or are being performed with Herschel/HIFI and the IRAM 30 m telescope in all the available bands of these two instruments, and with the Submillimeter Array (SMA) in the 280-355 GHz (∼0.9 mm) frequency range (see Kamiński et al 2013). Altogether, these works have revealed, and will continue to reveal, the chemical richness and complexity that can be present in the circumstellar envelopes of cool, high mass-loss O-rich stars.…”

Section: Introductionmentioning

confidence: 99%

HIFISTARSHerschel/HIFI observations of VY Canis Majoris

Alcolea

Bujarrabal

Planesas

et al. 2013

A&A

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Aims. The study of the molecular gas in the circumstellar envelopes of evolved stars is normally undertaken by observing lines of CO (and other species) in the millimetre-wave domain. In general, the excitation requirements of the observed lines are low at these wavelengths, and therefore these observations predominantly probe the cold outer envelope while studying the warm inner regions of the envelopes normally requires sub-millimetre (sub-mm) and far-infrared (FIR) observational data. Methods. To gain insight into the physical conditions and kinematics of the warm (100-1000 K) gas around the red hyper-giant VY CMa, we performed sensitive high spectral resolution observations of molecular lines in the sub-mm/FIR using the HIFI instrument of the Herschel Space Observatory. We observed CO, H 2 O, and other molecular species, sampling excitation energies from a few tens to a few thousand K. These observations are part of the Herschel guaranteed time key program HIFISTARS. Results. We detected the J = 6-5, J = 10-9, and J = 16-15 lines of 12 CO and 13 CO at ∼100, 300, and 750 K above the ground state (and the 13 CO J = 9-8 line). These lines are crucial for improving the modelling of the internal layers of the envelope around VY CMa. We also detected 27 lines of H 2 O and its isotopomers, and 96 lines of species such as NH 3 , SiO, SO, SO 2 HCN, OH and others, some of them originating from vibrationally excited levels. Three lines were not unambiguously assigned. Conclusions. Our observations confirm that VY CMa's envelope must consist of two or more detached components. The molecular excitation in the outer layers is significantly lower than in the inner ones, resulting in strong self-absorbed profiles in molecular lines that are optically thick in this outer envelope, for instance, low-lying lines of H 2 O. Except for the most abundant species, CO and H 2 O, most of the molecular emission detected at these sub-mm/FIR wavelengths arise from the central parts of the envelope. The spectrum of VY CMa is very prominent in vibrationally excited lines, which are caused by the strong IR pumping present in the central regions. Compared with envelopes of other massive evolved stars, VY CMa's emission is particularly strong in these vibrationally excited lines, as well as in the emission from less abundant species such as H 13 CN, SO, and NH 3 .

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Pure rotational spectra of TiO and TiO₂in VY Canis Majoris

Cited by 86 publications

References 48 publications

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

MILLIMETER/SUBMILLIMETER SPECTROSCOPY OF TiO (X³Δ_r): THE RARE TITANIUM ISOTOPOLOGUES

HIFISTARSHerschel/HIFI observations of VY Canis Majoris

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Pure rotational spectra of TiO and TiO2in VY Canis Majoris

Cited by 86 publications

References 48 publications

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

MILLIMETER/SUBMILLIMETER SPECTROSCOPY OF TiO (X3Δr): THE RARE TITANIUM ISOTOPOLOGUES

HIFISTARSHerschel/HIFI observations of VY Canis Majoris

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Resources

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Pure rotational spectra of TiO and TiO₂in VY Canis Majoris

MILLIMETER/SUBMILLIMETER SPECTROSCOPY OF TiO (X³Δ_r): THE RARE TITANIUM ISOTOPOLOGUES