A high geometric albedo and small size for the Haumea cluster member (24835) 1995 SM55 determined from a stellar occultation and photometric observations

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00643348" target="_blank" >RIV/67985815:_____/25:00643348 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0373304" target="_blank" >https://hdl.handle.net/11104/0373304</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202556498" target="_blank" >10.1051/0004-6361/202556498</a>

Result language

angličtina

Original language name

A high geometric albedo and small size for the Haumea cluster member (24835) 1995 SM55 determined from a stellar occultation and photometric observations

Original language description

Context. Trans-Neptunian objects (TNOs) are thought to be some of the most ancient and primitive bodies in our Solar System. Understanding their basic physical properties is crucial to unraveling their origin and the evolution of the outer Solar System beyond Neptune. Stellar occultations are a highly effective and sensitive method of studying these distant and faint objects, allowing us to gather essential information about their physical characteristics. (24835) 1995 SM55 is one of the few members of the Haumea orbital cluster and, therefore, is an especially relevant body to study within the TNO population.Aims. The main objectives of the present work are to determine the projected size, absolute magnitude, and geometric albedo of 1995 SM55 and to analyze the results compared to Haumea.Methods. We predicted a stellar occultation by this TNO for February, 25, 2024, carried out a specific campaign to observe the occultation, and derived the projected size and shape from the occultation observations using an elliptical fit to the occultation chords. We also analyzed a large set of photometric observations of (24835) 1995 SM55 to obtain the absolute magnitude and the rotational period. Finally, we combined these results to derive the geometric albedo of this TNO.Results. The occultation was successfully detected from seven instruments located at five different sites, 33 other sites reported negative detections. Using an elliptical fit to the occultation chords, we determined the size and shape of the limb of (24835) 1995 SM55 during the occultation: an ellipse with semi-axes (104.3 +/- 0.4) x (83.5 +/- 0.5) km. The area-equivalent diameter (D-eq,D-A) for this ellipse is 186.7 +/- 1.8 km. This is consistent with the upper limit of 250 km estimated from Herschel Observatory thermal data. From our photometric observations, we derived an absolute magnitude (HV) of 4.55 +/- 0.03, a phase slope parameter of 0.04 +/- 0.02 mag/deg, and a V R value of 0.37 +/- 0.05. The rotational variability has a maximum peak-to-valley amplitude (triangle m) of 0.05 mag, but we could not derive an unambiguous rotational period. Combining the projected size from the occultation with the absolute photometry, we obtained a geometric albedo in the V band (pV) of 0.80 +/- 0.04 for 1995 SM55. This value is remarkably high for a TNO and somewhat higher than that of Haumea, but consistent with the concept that 1995 SM55 is a member of the orbital cluster of Haumea.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

703

Issue of the periodical within the volume

Nov.

Country of publishing house

FR - FRANCE

Number of pages

13

Pages from-to

A147

UT code for WoS article

001626464600017

EID of the result in the Scopus database

2-s2.0-105021965743