Qualitative classification of extraterrestrial civilizations

Abridged: The interest towards searches for extraterrestrial civilizations (ETCs) was boosted by the discovery of thousands of exoplanets. We turn to the classification of ETCs for new considerations that may help to design better strategies for ETCs searches. We take a basic taxonomic approach to ETCs and investigate the implications of the new classification on ETCs observational patterns. We use as a counter-example to our qualitative classification the quantitative scheme of Kardashev. We propose a classification based on the abilities of ETCs to modify their environment and to integrate with it: Class 0 uses the environment as it is, Class 1 modifies the it to fit its needs, Class 2 modifies itself to fit the environment and Class 3 ETC is fully integrated with the environment. Combined with the classical Kardashev's scale our scheme forms a 2d scheme for interpreting ETC properties. The new framework makes it obvious that the available energy is not an unique measure of ETCs, it may not even correlate with how well that energy is used. The possibility for progress without increased energy consumption implies lower detectability, so the existence of a Kardashev Type III ETC in the Milky Way cannot be ruled out. This reasoning weakens the Fermi paradox, allowing the existence of advanced, yet not energy hungry, low detectability ETCs. The integration of ETCs with environment makes it impossible to tell apart technosignatures from natural phenomena. Thus, the most likely opportunity for SETI searches is to look for beacons, specifically set up by them for young civilizations like us (if they want to do that is a matter of speculation). The other SETI window is to search for ETCs at technological level close to ours. To rephrase the saying of A. Clarke, sufficiently advanced civilizations are indistinguishable from nature.Comment: accepted in A&A; 7 pages, 1 figure; the acknowledgements were updated in the new versio

VVV-WIT-12 and Its Fashionable Nebula: A 4 yr Long-period Young Stellar Object with a Light Echo?

© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/We report the serendipitous discovery of VVV-WIT-12, an unusual variable source that seems to induce variability in its surrounding nebula. The source belongs to the rare objects that we call WITs (short for What Is This?) discovered within the VISTA Variables in the Vía Láctea (VVV) survey. VVV-WIT-12 was discovered during a pilot search for light echoes from distant supernovae in the Milky Way using the near-IR images of the VVV survey. This source has an extremely red spectral energy distribution, consistent with a very reddened (A V ∼ 100 mag) long-period variable star (P ∼ 1525 days). Furthermore, it is enshrouded in a nebula that changes brightness and color with time, apparently in sync with the central source variations. The near-IR light curve and complementary follow-up spectroscopy observations are consistent with a variable young stellar object illuminating its surrounding nebula. In this case the source periodic variation along the cycles produces an unprecedented light echo in the different regions of the nebula.Peer reviewe

New VVV Survey Globular Cluster Candidates in the Milky Way Bulge

© 2017 The American Astronomical Society. All rights reserved.It is likely that a number of Galactic globular clusters remain to be discovered, especially toward the Galactic bulge. High stellar density combined with high and differential interstellar reddening are the two major problems for finding globular clusters located toward the bulge. We use the deep near-IR photometry of the VISTA Variables in the Vía Láctea (VVV) Survey to search for globular clusters projected toward the Galactic bulge, and hereby report the discovery of 22 new candidate globular clusters. These objects, detected as high density regions in our maps of bulge red giants, are confirmed as globular cluster candidates by their color-magnitude diagrams. We provide their coordinates as well as their near-IR color-magnitude diagrams, from which some basic parameters are derived, such as reddenings and heliocentric distances. The color-magnitude diagrams reveal well defined red giant branches in all cases, often including a prominent red clump. The new globular cluster candidates exhibit a variety of extinctions (0.06 < A Ks < 2.77) and distances (5.3 < D < 9.5 kpc). We also classify the globular cluster candidates into 10 metal-poor and 12 metal-rich clusters, based on the comparison of their color-magnitude diagrams with those of known globular clusters also observed by the VVV Survey. Finally, we argue that the census for Galactic globular clusters still remains incomplete, and that many more candidate globular clusters (particularly the low luminosity ones) await to be found and studied in detail in the central regions of the Milky Way.Peer reviewedFinal Accepted Versio

VISTA Variables in the <i>Vía Láctea</i> (VVV): Halfway Status and Results

The VISTA Variables in the Vía Láctea (VVV) survey is one of six near-infrared ESO public surveys, and is now in its fourth year of observing. Although far from being complete, the VVV survey has already delivered many results, some directly connected to the intended science goals (detection of variable stars, microlensing events, new star clusters), others concerning more exotic objects, e.g., novae. Now, at the end of the fourth observing period, and comprising roughly 50% of the proposed observations, the status of the survey, as well some of results based on the VVV data, are presented.Facultad de Ciencias Astronómicas y Geofísica

VVV WIT 003 Light curve

<p>VVV WIT 003. Ks band light curve from the VVV survey.</p> <p>The real nature of this object is still uncertain, the rise and decay of the event are not particularlly constrained, as can be seen in the figure.The last non detections observations were made in June 26 of 2013, then the observations in bright phase were taken within 12 days in May 2014. By May 2015 the source had already faded ~7 magnitudes, almost at the detection limit of our survey.</p

VVV WIT 003

<p>Near IR colors for the source VVV WIT 003. and Ks detections and upper and lower limits.</p> <p>This unclassified variable source from VVV survey had a increase of at least 7 magnitudes in the Ks band, the colors of the source one year after explotion suggest that the level of extinction is not particularly high compared to other sources nearby</p

ASASSN2018gq NIR spectrum

Near IR spectrum of the transient AT 2018apl (or ASASSN2018gq) obtained with the 4m Blanco Telescope at cerro Tololo, Chile<div><br></div><div>A flat spectrum is visible from our NIR observations, consistent with the observations obtained by ePESSTO team (http://www.astronomerstelegram.org/?read=11509)</div><div><br></div

VISTA Variables in the Vía Láctea (VVV): Halfway Status and Results

The VISTA Variables in the Vía Láctea (VVV) survey is one of six near-infrared ESO public surveys, and is now in its fourth year of observing. Although far from being complete, the VVV survey has already delivered many results, some directly connected to the intended science goals (detection of variable stars, microlensing events, new star clusters), others concerning more exotic objects, e.g., novae. Now, at the end of the fourth observing period, and comprising roughly 50% of the proposed observations, the status of the survey, as well some of results based on the VVV data, are presented.Fil: Hempel, Maren. Pontificia Universidad Católica de Chile; Chile. The Milky Way Millennium Nucleus; ChileFil: Minniti, Dante. Pontificia Universidad Católica de Chile; Chile. Vatican Observatory; ItaliaFil: Dékány, István. Pontificia Universidad Católica de Chile; ChileFil: Saito, Roberto K.. Pontificia Universidad Católica de Chile; Chile. Universidade Federal de Sergipe; BrasilFil: Lucas, Philip W.. University Of Hertfordshire; Reino UnidoFil: Emerson, Jim P.. Queen Mary University of London; Reino UnidoFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aigrain, Suzanne. University of Exeter; Reino UnidoFil: Alonso, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Alonso García, Javier. Pontificia Universidad Católica de Chile; ChileFil: Amôres, Eduardo B.. Universidade de Lisboa; PortugalFil: Angeloni, Rodolfo. Pontificia Universidad Católica de Chile; ChileFil: Arias, Julia. Universidad de La Serena; ChileFil: Bandyopadhyay, Reba. University of Florida; Estados UnidosFil: Barba, Rodolfo Hector. Universidad de La Serena; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barbuy, Beatriz. Universidade de São Paulo; BrasilFil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Beamin, Juan Carlos. Pontificia Universidad Católica de Chile; ChileFil: Bedin, Luigi. Space Telescope Science Institute; Estados UnidosFil: Bica, Eduardo. Universidade Federal do Rio Grande do Sul; BrasilFil: Borissova, Jordanka. Universidad de Chile; ChileFil: Bronfman, Leonardo. Universidad de Chile; ChileFil: Carraro, Giovanni. European Southern Observatory; ChileFil: Catelan, Márcio. Pontificia Universidad Católica de Chile; ChileFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Contreras, Carlos. Pontificia Universidad Católica de Chile; ChileFil: Cross, Nicholas. University of Edinburgh; Reino UnidoFil: Davis, Christopher. Joint Astronomy Centre; Estados UnidosFil: de Grijs, Richard. Peking University; ChinaFil: Drew, Janet E.. University Of Hertfordshire; Reino UnidoFil: Fariña, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Feinstein Baigorri, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Fernandez Lajus, Eduardo Eusebio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Folkes, Stuart. University Of Hertfordshire; Reino UnidoFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Geisler, Douglas. Universidad de Concepción; ChileFil: Gieren, Wolfgang. Universidad de Concepción; ChileFil: Goldman, Bertrand. Max Planck Institute for Astronomy; AlemaniaFil: González, Oscar. European Southern Observatory; ChileFil: Gosling, Andrew. University of Oxford; Reino UnidoFil: Gunthardt, Guillermo Ivan. Universidad de La Serena; ChileFil: Gurovich, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Hambly, Nigel C.. University of Edinburgh; Reino UnidoFil: Hanson, Margaret. University of Cincinnati; Estados UnidosFil: Hoare, Melvin. University of Leeds; Reino UnidoFil: Irwin, Mike J.. University of Cambridge; Reino UnidoFil: Ivanov, Valentin D.. European Southern Observatory; ChileFil: Jordán, Andrés. Pontificia Universidad Católica de Chile; ChileFil: Kerins, Eamonn. University of Manchester; Reino UnidoFil: Kinemuchi, Karen. National Aeronautics and Space Administration; Estados UnidosFil: Kurtev, Radostin. Universidad de Valparaíso; ChileFil: Longmore, Andy. University of Edinburgh; Reino UnidoFil: López Corredoira, Martin. Instituto de Astrofísica de Canarias; EspañaFil: Maccarone, Tom. Texas Tech University; Estados UnidosFil: Martín, Eduardo. Instituto de Astrofísica de Canarias; EspañaFil: Masetti, Nicola. Instituto di Astrofisica Spaziale e Fisica Cosmica de Bologna; ItaliaFil: Mennickent, Ronald E.. Universidad de Concepción; ChileFil: Merlo, David. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Messineo, Maria. Rochester Institute of Technology; Estados UnidosFil: Mirabel Miquele, Igor Felix. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Monaco, Lorenzo. European Southern Observatory; ChileFil: Moni Bidin, Christian. Universidad Católica del Norte; ChileFil: Morelli, Lorenzo. Università di Padova; ItaliaFil: Padilla, Nelson. Pontificia Universidad Católica de Chile; ChileFil: Palma, Tali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Parker, Quentin. Macquarie University; AustraliaFil: Pavani, Daniela. Universidade Federal do Rio Grande do Sul; BrasilFil: Pietrukowicz, Pawel. Nicolaus Copernicus Astronomical Center; PoloniaFil: Pietrzynski, Grzegorz. Imperial College London; Reino UnidoFil: Pignata, Giuliano. Universidad Andrés Bello; ChileFil: Rejkuba, Marina. European Southern Observatory; ChileFil: Rojas, Alejandra. Pontificia Universidad Católica de Chile; ChileFil: Roman Lopes, Alexandre. Universidad de La Serena; ChileFil: Ruiz, María Teresa. Universidad de Chile; ChileFil: Sale, Stuart E.. Pontificia Universidad Católica de Chile; ChileFil: Saviane, Ivo. European Southern Observatory; ChileFil: Schreiber, Matthias R.. Universidad de Valparaíso; ChileFil: Schröder, Anja C.. Hartebeesthoek Radio Astronomy Observatory; SudáfricaFil: Sharma, Saurabh. Universidad de Valparaíso; ChileFil: Smith, Michael. University Of Kent; Reino UnidoFil: Sodré Jr., Laerte. Universidade de Sao Paulo; BrasilFil: Soto, Mario. Universidad de La Serena; ChileFil: Stephens, Andrew W.. National Astronomical Observatory of Japan; JapónFil: Tamura, Motohide. Gemini Observatory; Estados UnidosFil: Tappert, Claus. Universidad de Valparaíso; ChileFil: Thompson, Mark A.. University Of Hertfordshire; Reino UnidoFil: Toledo, Ignacio. ALMA Observatory; ChileFil: Valenti, Elena. European Southern Observatory; ChileFil: Vanzi, Leonardo. Pontificia Universidad Católica de Chile; ChileFil: Weidmann, Walter Alfredo. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zoccali, Manuela. Pontificia Universidad Católica de Chile; Chil