Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2509.15384

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

J. L. Ortiz·N. Morales·B. Sicardy·F. L. Rommel·F. Braga-Ribas·Y. Kilic·E. Fernández-Valenzuela·J. L. Rizos·B. Morgado·L. Catani·M. Kretlow·J. M. Gómez-Limón·J. Desmars·P. Santos-Sanz·O. Erece·I. Akoz·K. Uluc·S. Kaspi·A. Marciniak·V. Turcu·D. Moldovan·A. Sonka·E. Petrescu·A. Nedelcu·C. Nehir·R. Morales·R. Duffard·D. Souami·W. Thuillot·J. I. B. Camargo·R. Vieira-Martins·J. Lecacheux·A. Alvarez-Candal·M. Assafin·G. Benedetti-Rossi·A. Gomes-Junior·R. Boufleur·U. Hopp·C. Goessl·M. Schmidt·A. Takey·A. M. Abdelaziz·H. Mikuz·A. Mohar·J. Skvarc·O. Schreurs·M. Lecossois·T. Janik·M. N. Bagiran·S. Fişek·S. Alis·F. K. Yelkenci·M. Acar·N. Takacs·R. Szakats·A. Pal·J. Manek·B. A. Dumitru·K. Gazeas·F. Ursache·D. Nardiello·V. Nascimbeni·M. Rottenborn·E. Sonbas·W. Ogloza·A. Nastasi·S. Leonini·M. Conti·P. Rosi·L. M. Tinjaca Ramirez·L. Bellizi·A. Marchini·G. Verna·A. Solmaz·M. Tekes·D. Antuszewicz·D. Pica·D. Ilic·M. Grozdanovic·L. Stoian·P. Bacci·M. Maestripieri·G. Krannich·R. Bacci·M. Altan·K. Hornoch·R. Nesci·F. Ciabattari·G. M. Szabó·J. Kovács·Z. Garai·Z. Bora·P. Zeleny·B. Gaehrken·M. Fiedler·L. Curelaru·S. Ion·R. Schaefer·J. Kubánek·P. Delincak
View original source ↗Read source document ↗Export metadata ↓

Abstract

Trans-Neptunian objects (TNOs) are among the most ancient bodies of the solar system. Understanding their physical properties is key to constraining their origin and the evolution of the outer regions beyond Neptune. Stellar occultations provide highly accurate size and shape information. (24835) 1995 SM55 is one of the few members of the Haumea cluster and thus of particular interest. We aimed to determine its projected size, absolute magnitude, and geometric albedo, and to compare these with Haumea. A stellar occultation on 25 February 2024 was observed from five sites, with seven positive detections and 33 negative chords. An elliptical fit to the occultation chords yields semi-axes of $(104.3 \pm 0.4) \times (83.5 \pm 0.5)$ km, giving an area-equivalent diameter of $186.7 \pm 1.8$ km, smaller than the 250 km upper limit from Herschel thermal data. Photometry provides an absolute magnitude $H_V = 4.55 \pm 0.03$, a phase slope of $0.04 \pm 0.02$ mag/deg, and a $V-R = 0.37 \pm 0.05$. The rotational variability has an amplitude $Δm = 0.05$ mag, but the period remains uncertain. Combining occultation and photometry, we derive a geometric albedo $p_V = 0.80 \pm 0.04$, one of the highest values measured for a TNO. This value is slightly higher than that of Haumea, consistent with the interpretation that 1995 SM55 belongs to the Haumea cluster.

Explore related subjects

astro-ph.EPastro-ph.SR

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J. L. Ortiz, N. Morales, B. Sicardy, F. L. Rommel, F. Braga-Ribas, Y. Kilic, E. Fernández-Valenzuela, J. L. Rizos, B. Morgado, L. Catani, M. Kretlow, J. M. Gómez-Limón, J. Desmars, P. Santos-Sanz, O. Erece, I. Akoz, K. Uluc, S. Kaspi, A. Marciniak, V. Turcu, D. Moldovan, A. Sonka, E. Petrescu, A. Nedelcu, C. Nehir, R. Morales, R. Duffard, D. Souami, W. Thuillot, J. I. B. Camargo, R. Vieira-Martins, J. Lecacheux, A. Alvarez-Candal, M. Assafin, G. Benedetti-Rossi, A. Gomes-Junior, R. Boufleur, U. Hopp, C. Goessl, M. Schmidt, A. Takey, A. M. Abdelaziz, H. Mikuz, A. Mohar, J. Skvarc, O. Schreurs, M. Lecossois, T. Janik, M. N. Bagiran, S. Fişek, S. Alis, F. K. Yelkenci, M. Acar, N. Takacs, R. Szakats, A. Pal, J. Manek, B. A. Dumitru, K. Gazeas, F. Ursache, D. Nardiello, V. Nascimbeni, M. Rottenborn, E. Sonbas, W. Ogloza, A. Nastasi, S. Leonini, M. Conti, P. Rosi, L. M. Tinjaca Ramirez, L. Bellizi, A. Marchini, G. Verna, A. Solmaz, M. Tekes, D. Antuszewicz, D. Pica, D. Ilic, M. Grozdanovic, L. Stoian, P. Bacci, M. Maestripieri, G. Krannich, R. Bacci, M. Altan, K. Hornoch, R. Nesci, F. Ciabattari, G. M. Szabó, J. Kovács, Z. Garai, Z. Bora, P. Zeleny, B. Gaehrken, M. Fiedler, L. Curelaru, S. Ion, R. Schaefer, J. Kubánek, P. Delincak. 2025-09-18. A high geometric albedo and small size of the Haumea cluster member (24835) 1995 SM55 from a stellar occultation and photometric observations. https://doi.org/10.1051/0004-6361%2F202556498

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Radiating Bondi Flows I: Dimensionless Framework and Constant Opacity Solutions

In this paper, we extend the foundational work of Bondi (1952) to include the effects of radiative feedback in gas-pressure-dominated environments. We construct steady-state spherically symmetric accretion solutions including radiative heating and cooling. Under the simplifying assumption of a constant opacity, the solutions are controlled by four dimensionless parameters: the adiabatic index $γ$, optical depth through the Bondi radius $τ_B$, dimensionless luminosity at infinity $\tilde{L}_\infty$, and a characteristic dimensionless cooling time $β$. We present numerical solutions across the dimensionless parameter space $(τ_B, \tilde{L}_\infty, β)\in [10^{-3}, 10^3]$. Contrary to radiation-pressure-dominated environments, radiative feedback primarily operates to suppress accretion -- particularly at high $τ_B$, $\tilde{L}_\infty$, and/or $β$. We also present analytic descriptions confirming the suppressive nature of this feedback and give the scalings for the accretion rate $\dot{M}\sim \tilde{L}_\infty^{-5/4}$ at large $\tilde{L}_\infty$, $\dot{M}\sim τ_B^{-10/11}β^{-5/11}$ at large $τ_B$, and $\dot{M}\sim (\tilde{L}_\inftyτ_B)^{-5/8}$ for large $\tilde{L}_\inftyτ_B$. We discuss the potential role of convection in these steady-state solutions, and the particular relevance to problems of planet formation where radiative heating is significant, but the system remains in the gas-pressure-dominated regime.

astro-ph.EP↗
arXiv2026

Radiating Bondi Flows II: Giant Planet Accretion Models

In the core accretion model of giant planet formation, the late stages of runaway growth are regulated by the hydrodynamic infall of gas from the protoplanetary disk. For a subset of planet-disk pairings, this scenario is analogous to the classical Bondi problem, which has motivated a Bondi-like parameterization of accretion in some population synthesis models. Existing models and the associated classical Bondi rate however, are predicated upon an adiabatic equation of state. In reality, the planet and its associated accretion shock supply a luminosity that substantially heats the accretion flow. In Paper I of this series, we demonstrate that such radiative feedback can dramatically suppress accretion by orders of magnitude. Here we quantify this effect under realistic planet-forming conditions. We find that for planets forming in an unperturbed disk, accretion is suppressed by 1-2 orders of magnitude interior to $\sim 10$ AU. For planets that open a gap, this feedback is less dramatic and the effect is $\sim$ 1 order in magnitude. We investigate the effect of various assumptions regarding dust opacities, shock efficiency, and planet radius and find this radiative suppression mechanism to be fairly insensitive to these effects. We also perform full time-dependent simulations demonstrating that the associated adverse entropy profiles are accurate and stable to convection. A simple and flexible set of open-source tools are provided to incorporate this radiative feedback into existing accretion models and population synthesis frameworks.

astro-ph.EP↗
arXiv2026

Assessing the Impact of High-Resolution Imaging on Statistical Validation of TESS Planet Candidates

High-resolution imaging is widely used to constrain false-positive scenarios in exoplanet validation, but it is a finite follow-up resource that reaches only a subset of candidates, and its population-level impact on validation outcomes has not been quantified through controlled removal experiments. Using an automated pipeline built on TRICERATOPS, we compute the false-positive probability (FPP) of 443 TESS planet candidates. For the 264 planet candidates with high-resolution imaging observations, we compute FPP with and without the corresponding contrast curves, allowing us to quantify the impact of the additional data. We find that 72% of 68 contrast-curve bearing validated planets would fail validation without their adopted contrast curves. The fraction requiring imaging decreases with increasing planet size, from 100% below $1.7~R_\oplus$ to $33\%$ above $4~R_\oplus$: within our sample and TRICERATOPS-based analysis, the availability of high-resolution imaging directly limits the yield of small-planet validation and the supply of validated targets for atmospheric characterization. Our analysis statistically validates 64 new TESS planets with sizes spanning 0.94 to 7.83 $R_\oplus$ across hosts of spectral type M through F. Four of these are highly amenable to JWST observations based on the transmission and emission spectroscopy metrics, and each achieves validation only with its imaging constraint.

astro-ph.EP↗