Size determination of the Centaur Chariklo from millimeter-wavelength bolometer observations

Altenhoff, W. J.; Menten, K. M.; Bertoldi, F.

doi:10.1051/0004-6361:20000543

Cited by 31 publications

(17 citation statements)

References 25 publications

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“…As shown by Young et al (2001), even if a "detailed balance" model is envisaged (Trafton et al 1998), the CO atmospheric abundance cannot exceed (0.1-0.5)%. The only situation that our upper limits can exclude is the case of isolated CO patches at temperatures similar or higher than N 2 ice, which would dictate CO/N 2 mixing ratios of 5-20% for T = 35−50 K. This situation is unlikely because (Bus et al 1996;Groussin et al 2000;Campins et al 1994;Altenhoff & Stumpff 1995); Pholus (Davies et al 1993); Chariklo (Jewitt & Kalas 1998;Altenhoff et al 2001); for other objects, they were calculated from optical photometry alone, assuming a geometrical albedo of 0.04.…”

Section: Plutomentioning

confidence: 90%

Search for CO gas in Pluto, Centaurs and Kuiper Belt objects at radio wavelengths

Bockelée‐Morvan

Lellouch

Biver

et al. 2001

A&A

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Abstract.We have searched for several rotational lines of CO in the Pluto-Charon system, Centaurs (Chiron, Pholus, Nessus, Asbolus, Chariklo and 1998 SG35) and Kuiper Belt objects (1994 TB, 1996 TL66, 1996 TO66, 1996 TP66 and 1998. The observations were performed with the 30 m telescope of the Institut de Radioastronomie Millimétrique for Pluto/Charon, and with the James Clerk Maxwell Telescope and Caltech Submillimeter Observatory for Centaurs and Kuiper Belt objects. A tentative 4.5-σ J(2−1) CO line is present in the Pluto/Charon spectrum, which requires further confirmation. Assuming that Charon does not contribute to the CO emission, an upper limit of 1.2% and 7% is obtained for the CO/N2 mixing ratio in Pluto's atmosphere, using the atmospheric thermal structure derived from the Stansberry et al. (1994, Icarus 111, 503) and Strobel et al. (1996, Icarus 120, 266) models, respectively. These upper limits are more constraining (by more than a factor of 6) than the upper limits reported by Young et al. (2001, Icarus, in press) from near-IR spectroscopy. None of the Centaurs or Kuiper Belt objects (KBO) were detected in CO. The CO production rate upper limit obtained for Chiron (3−5× 10 27 mol s −1 ) over 1998-2000 years is a factor of 10 lower than the CO production rate derived from the marginal CO detection obtained in June 1995 by Womack & Stern (1999, Astron. Vestnik 33, 216), using same modelling of CO emission. Upper limits obtained for other Centaurs are typically ∼10 28 mol s −1 , and between 1 and 5 × 10 28 mol s −1 for the best observed KBOs. The comparison between these upper limits and the CO outgassing rates of comet C/1995 O1 (Hale-Bopp) measured at large distances from the Sun shows that Centaurs and KBOs underwent significant CO-devolatilization since their formation.

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Section: Plutomentioning

confidence: 90%

Search for CO gas in Pluto, Centaurs and Kuiper Belt objects at radio wavelengths

Bockelée‐Morvan

Lellouch

Biver

et al. 2001

A&A

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“…The solid bold line and the hatched band represent our determination of 118 ± 6 km. Altenhoff et al (2001). are presented in Table 7. The recent observations of Peixinho et al (2001) present evidences for variations of the absolute magnitude of Chariklo over a few months.…”

Section: Radius Thermal Inertia and Geometric Albedo Of The Nucleusmentioning

confidence: 99%

“…As done for Chiron, we minimized the χ 2 expression, using the infrared (Jewitt & Kalas 1998) and radio (Altenhoff et al 2001) constraints, and we derived a radius of 118 ± 6 km and a thermal inertia of 0 +2 −0 MKS. As noted previously, this results depend on η.…”

Section: Radius Thermal Inertia and Geometric Albedo Of The Nucleusmentioning

confidence: 99%

Properties of the nuclei of Centaurs Chiron and Chariklo

Groussin

Lamy

Jordá

2004

A&A

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Abstract. We analyze visible, infrared, radio and spectroscopic observations of 2060 Chiron in a synthetic way to determine the physical properties of its nucleus. From visible observations performed from 1969 to 2001, we determine an absolute V magnitude for the nucleus of 7.28 ± 0.08 with an amplitude of 0.16 ± 0.03, implying a nearly spherical nucleus with a ratio of semi-axes a/b = 1.16 ± 0.03. Infrared observations at 25, 60, 100 and 160 µm (i.e., covering the broad maximum of the spectral energy distribution) obtained with the Infrared Space Observatory Photometer (ISOPHOT) in June 1996 when Chiron was near its perihelion are analyzed with a thermal model which considers an intimate mixture of water ice and refractory materials and includes heat conduction into the interior of the nucleus. We find a very low thermal inertia of 3and a radius of 71 ± 5 km. Combining the visible and infrared observations, we derive a geometric albedo of 0.11 ± 0.02. We find that the observed spectra of Chiron can be fitted by a mixture of water ice (∼30%) and refractory (∼70%) grains, and that this surface model has a geometric albedo consistent with the above value. We also analyze the visible, infrared and radio observations of Chariklo (1997 CU26) and derive a radius of 118 ± 6 km, a geometric albedo of 0.07 ± 0.01 and a thermal inertia of 0A mixture of water ice (∼20%) and refractory (∼80%) grains is compatible with the near-infrared spectrum and the above albedo.

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“…From all observable parameters of KBOs the size and albedo information is scarce: only one angular size could be measured directly , and two indirectly by the sensitivity-limited radio photometric method, measuring their thermal emission: the observed flux density is proportional to the cross section of the KBO and to the independently known brightness temperature (Altenhoff et al 2001). …”

Section: Observations Of 7 Kbos Bymentioning

confidence: 99%

“…Here we want to extend the radio photometric size determinations of minor planets (Altenhoff et al 1994(Altenhoff et al , 1995(Altenhoff et al , 2001 to more distant minor planets and compare the results systematically with other published radio size measurements for an improved set of sizes and albedos. …”

Section: Observations Of 7 Kbos Bymentioning

confidence: 99%

Size estimates of some optically bright KBOs

Altenhoff

Bertoldi

Menten

2004

A&A

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Abstract. Seven recently detected optically "bright" Kuiper-Belt-Objects (KBOs) were observed at 250 GHz using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30 m telescope. Only the optical binary KBO (47 171) 1999 TC36 was detected, whose components differ optically by ∆m ≈ 2 mag. Assuming that the derived mean geometric albedo of p = 0.05 is identical for both, the component diameters become 566 and 225 km. For the other six objects upper limits to their sizes and lower limits for their albedos were obtained. The geometric albedo, p, for (28978) Ixion is surprisingly large, ≥0.15. For a consistent comparison all published radio photometric data of KBOs and Centaurs were analyzed again: the average geometric albedo is found to be ≈0.08.

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Size determination of the Centaur Chariklo from millimeter-wavelength bolometer observations

Cited by 31 publications

References 25 publications

Search for CO gas in Pluto, Centaurs and Kuiper Belt objects at radio wavelengths

Search for CO gas in Pluto, Centaurs and Kuiper Belt objects at radio wavelengths

Properties of the nuclei of Centaurs Chiron and Chariklo

Size estimates of some optically bright KBOs

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