The shape of (7) Iris as evidence of an ancient large impact?

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F19%3A10405859" target="_blank" >RIV/00216208:11320/19:10405859 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=r9F6fI4YPq" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=r9F6fI4YPq</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/201834541" target="_blank" >10.1051/0004-6361/201834541</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The shape of (7) Iris as evidence of an ancient large impact?

Popis výsledku v původním jazyce

Context. Asteroid (7) Iris is an ideal target for disk-resolved imaging owing to its brightness (V similar to 7-8) and large angular size of 0.33 &apos;&apos; during its apparitions. Iris is believed to belong to the category of large unfragmented asteroids that avoided internal differentiation, implying that its current shape and topography may record the first few 100 Myr of the solar system&apos;s collisional evolution. Aims. We recovered information about the shape and surface topography of Iris from disk-resolved VLT/SPHERE/ZIMPOL images acquired in the frame of our ESO large program. Methods. We used the All-Data Asteroid Modeling (ADAM) shape reconstruction algorithm to model the 3D shape of Iris, using optical disk-integrated data and disk-resolved images from SPHERE and earlier AO systems as inputs. We analyzed the SPHERE images and our model to infer the asteroid&apos;s global shape and the morphology of its main craters. Results. We present the 3D shape, volume-equivalent diameter D-eq = 214 +/- 5 km, and bulk density rho = 2.7 +/- 0.3 g cm(-3) of Iris. Its shape appears to be consistent with that of an oblate spheroid with a large equatorial excavation. We identified eight putative surface features 20-40 km in diameter detected at several epochs, which we interpret as impact craters, and several additional crater candidates. Craters on Iris have depth-to-diameter ratios that are similar to those of analogous 10 km craters on Vesta. Conclusions. The bulk density of Iris is consistent with that of its meteoritic analog based on spectroscopic observations, namely LL ordinary chondrites. Considering the absence of a collisional family related to Iris and the number of large craters on its surface, we suggest that its equatorial depression may be the remnant of an ancient (at least 3 Gyr) impact. Iris&apos;s shape further opens the possibility that large planetesimals formed as almost perfect oblate spheroids. Finally, we attribute the difference in crater morphology between Iris and Vesta to their different surface gravities, and the absence of a substantial impact-induced regolith on Iris.

Název v anglickém jazyce

The shape of (7) Iris as evidence of an ancient large impact?

Popis výsledku anglicky

Context. Asteroid (7) Iris is an ideal target for disk-resolved imaging owing to its brightness (V similar to 7-8) and large angular size of 0.33 &apos;&apos; during its apparitions. Iris is believed to belong to the category of large unfragmented asteroids that avoided internal differentiation, implying that its current shape and topography may record the first few 100 Myr of the solar system&apos;s collisional evolution. Aims. We recovered information about the shape and surface topography of Iris from disk-resolved VLT/SPHERE/ZIMPOL images acquired in the frame of our ESO large program. Methods. We used the All-Data Asteroid Modeling (ADAM) shape reconstruction algorithm to model the 3D shape of Iris, using optical disk-integrated data and disk-resolved images from SPHERE and earlier AO systems as inputs. We analyzed the SPHERE images and our model to infer the asteroid&apos;s global shape and the morphology of its main craters. Results. We present the 3D shape, volume-equivalent diameter D-eq = 214 +/- 5 km, and bulk density rho = 2.7 +/- 0.3 g cm(-3) of Iris. Its shape appears to be consistent with that of an oblate spheroid with a large equatorial excavation. We identified eight putative surface features 20-40 km in diameter detected at several epochs, which we interpret as impact craters, and several additional crater candidates. Craters on Iris have depth-to-diameter ratios that are similar to those of analogous 10 km craters on Vesta. Conclusions. The bulk density of Iris is consistent with that of its meteoritic analog based on spectroscopic observations, namely LL ordinary chondrites. Considering the absence of a collisional family related to Iris and the number of large craters on its surface, we suggest that its equatorial depression may be the remnant of an ancient (at least 3 Gyr) impact. Iris&apos;s shape further opens the possibility that large planetesimals formed as almost perfect oblate spheroids. Finally, we attribute the difference in crater morphology between Iris and Vesta to their different surface gravities, and the absence of a substantial impact-induced regolith on Iris.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Astronomy &amp; Astrophysics [online]

ISSN

1432-0746

e-ISSN

—

Svazek periodika

624

Číslo periodika v rámci svazku

duben

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

17

Strana od-do

A121

Kód UT WoS článku

000465368300002

EID výsledku v databázi Scopus

2-s2.0-85065230444