J/ApJ/889/L30ivo://CDS.VizieR/J/ApJ/889/L30doi:10.26093/cds/vizier.18899030CDSLin H.W.Lee C.-H.Gerdes D.W.Adams F.C.Becker J.Napier K.,Markwardt L.2021-09-29T11:58:14Z2021-08-12T12:12:45ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frcometsvisible-astronomyspectroscopy2I/Borisov is the first-ever observed interstellar comet (and the second detected interstellar object (ISO)). It was discovered on 2019 August 30 and has a heliocentric orbital eccentricity of ~3.35, corresponding to a hyperbolic orbit that is unbound to the Sun. Given that it is an ISO, it is of interest to compare its properties-such as composition and activity-with the comets in our solar system. This study reports low-resolution optical spectra of 2I/Borisov. The spectra were obtained by the MDM Observatory Hiltner 2.4m telescope/Ohio State Multi-Object Spectrograph (on 2019 October 31.5 and November 4.5, UT). The wavelength coverage spanned from 3700 to 9200{AA}. The dust continuum reflectance spectra of 2I/Borisov show that the spectral slope is steeper in the blue end of the spectrum (compared to the red). The spectra of 2I/Borisov clearly show CN emission at 3880{AA}, as well as C2 emission at both 4750 and 5150{AA}. Using a Haser model to covert the observed fluxes into estimates for the molecular production rates, we find Q(CN)=2.4+/-0.2x10^24^s^-1^, and Q(C_2_)=(5.5+/-0.4)x10^23^s^-1^ at the heliocentric distance of 2.145au. Our Q(CN) estimate is consistent with contemporaneous observations, and the Q(C_2_) estimate is generally below the upper limits of previous studies. We derived the ratio Q(C_2_)/Q(CN)=0.2+/-0.1, which indicates that 2I/Borisov is depleted in carbon-chain species, but is not empty. This feature is not rare for the comets in our solar system, especially in the class of Jupiter-family comets.2020ApJ...889L..30Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/889/L30CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/634/L6 : NIR spectrum of interstellar object 2I/Borisov (Yang+, 2020)J/ApJ/889/L38 : Opt. spectroscopic investigations of 2I/Borisov (Kareta+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/889/L30https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/889/L30http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/889/L30https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/889/L30https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/889/L30http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/889/L30GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/889/L30/coadFlattened and coadded Hiltner 2.4m/OSMOS spectra of 2I/Borisov (Data behind Figure 1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3500/9200] Wavelength in Agstrom units0.1nmem.wlfloatFlux[-8.5e-16/9.4e-16] Flux in erg/s/cm^2^/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdoubleJ/ApJ/889/L30/2i_nov0404 November 2019 Hiltner 2.4m/OSMOS spectra of 2I/Borisov (Data behind Figure 1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3500/9200] Wavelength in Agstrom units0.1nmem.wlintFluxFlux in erg/s/cm^2^/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdoubleJ/ApJ/889/L30/2i_oct3131 October 2019 Hiltner 2.4m/OSMOS spectra of 2I/Borisov (Data behind Figure 1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3500/9200] Wavelength in Agstrom units0.1nmem.wlintFluxFlux in erg/s/cm^2^/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdoubleJ/ApJ/889/L30/s_nov04Solar spectrum taken 04 November 2019recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3500/9200] Wavelength in Angstrom units0.1nmem.wlintFlux[1.1e-13/3.7e-13] Flux in erg/s/cm^2^/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdoubleJ/ApJ/889/L30/s_oct31Solar spectrum taken 31 October 2019recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3500/9200] Wavelength in Angstrom units0.1nmem.wlintFlux[1.1e-13/3.7e-13] Flux in erg/s/cm^2^/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdouble